NOTIZIARIO Neutroni e Luce di Sincrotrone - Issue 8 n.2, 2003

Rivista del Consiglio Nazionale delle Ricerche

NOTIZIARIO Neutroni e Luce di Sincrotrone

ISSN 1592-7822

Vol. 8 n. 2

Luglio 2003 - Aut. Trib. Roma n. 124/96 del 22-03-96 - Sped. Abb. Post. 70% Filiale di Roma - C.N.R. p.le A. Moro 7, 00185 Roma

www.cnr.it/neutronielucedisincrotrone

NOTIZIARIO Neutroni e Luce di Sincrotrone

Rivista del Consiglio Nazionale delle Ricerche Cover photo: Elettra Italian national, synchrotron radiation, laboratory located in Basovizza in the outskirts of Trieste. (foto: Barnabà)

SOMMARIO EDITORIALE

...............................................................................................................................................

2

C. Andreani

RASSEGNA SCIENTIFICA The Elettra Synchrotron Radiation Laboratory ........................................................................................................................... 3 G. Paolucci

The Circular Polarization Beamline at Elettra: Status and Perspectives ...................................................... 10 Il

NOTIZIARIO Neutroni e Luce di Sincrotrone

è pubblicato a

cura del C.N.R. in collaborazione con la Facoltà di Scienze M.F.N. e il Dipartimento di Fisica dell’Università degli Studi di Roma “Tor Vergata”.

NOTIZIARIO Neutroni e Luce di Sincrotrone

T. Prosperi, S. Turchini and N. Zema

GEM: a Shining Light in the ISIS Crown ....................................................................................................................... 19 P.G. Radaelli, A.C. Hannon and L.C. Chapon

Vol. 8 n. 2 Luglio 2003 Autorizzazione del Tribunale di Roma n. 124/96 del 22-03-96

DOVE NEUTRONI DIRETTORE RESPONSABILE:

C. Andreani COMITATO DI DIREZIONE:

M. Apice, P. Bosi COMITATO DI REDAZIONE:

L. Avaldi, F. Aliotta, F. Carsughi, G. Ruocco.

INES - Italian Neutron Experimental Station Realisation of a neutron diffractometer, downstream from the TOSCA spectrometer, at ISIS (UK) ....................................................................................................................... 27 M. Zoppi

SEGRETERIA DI REDAZIONE:

D. Catena HANNO COLLABORATO

COMMISSIONI SCIENTIFICHE ....................................................................................................

35

ATTIVITA’ ITALIANA ............................................................................................................................

45

A QUESTO NUMERO:

R. Leckey, C. Petrillo, M.A. Ricci, N. Sasanelli, M. Zoppi GRAFICA E STAMPA:

om grafica via Fabrizio Luscino 73 00174 Roma

PROGETTO E.S.S. E.S.S.: the discussion continues .............................................................. 47 F. Carsughi

Finito di stampare nel mese di Luglio 2003 PER NUMERI ARRETRATI E INFORMAZIONI EDITORIALI:

Desy Catena Università degli Studi di Roma “Tor Vergata”, Presidenza Facoltà di Scienze M.F.N. via della Ricerca Scientifica, 1 00133 Roma Tel: +39 6 72594100 Fax: +39 6 2023507 E-mail: desy.catena@uniroma2.it

SCUOLE E CONVEGNI....................................................................................................................

VARIE .........................................................................................................................................................

CALENDARIO ........................................................................................................................................

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EDITORIALE

F

rom this issue the Notiziario Neutroni e

On April the 8th the UK government announced a

Luce di Sincrotrone journal is also on web

commitment of about 100M pounds for the

at the site address

construction of a second target station at the ISIS

www.cnr.it/neutronielucedisincrotrone.

Pulsed Neutron and Muon Facility, sited at the

Our readers will continue to receive the printed

Rutherford Appleton Laboratory.

journal with the additional opportunity to read on

Meeting reports included in this issue provide timely

the web about present and past articles, synchrotron

coverage of the recent past and near future activity of

and neutron news, meeting reports and much more,

the Italian Community in synchrotron and neutron

addressed to scientists who have an interest in

research. Scientific research is sorted, as tradition,

neutron scattering research in a wide spectrum of

from a broad array of articles.

disciplines.

This time we welcome an article by G. Paolucci on

Good news for the neutron community!

the ELETTRA Synchrotron Radiation Laboratory;

On December the 4th 2002, the Governments of

T. Prosperi et al. give us a contribution on a well

France, Germany and the United Kingdom agreed to

established synchrotron instrument, the Circular

an extension of the 1971 Inter-governmental

Polarization Beamline at ELETTRA, while by

Convention on the international research institute

P. Radaelli writes on the General Materials Neutron

known as the Institut Max von Laue - Paul Langevin

Diffractometer-GEM at ISIS, both excellent

(ILL) in Grenoble, France for further ten years.

instruments for materials research.

This act extends the duration of the Convention and

Last but not least I would like to congratulate JoĂŤl

related subsequent agreements to the year 2013, thus

Mesot, new editor of the splendid journal Neutron

guaranteeing continuity in the field of fundamental

News, and thank warmly Jerry Lander, director

and applied research with neutrons at the ILL.

emeritus of the journal, for his constant and valuable

On May the 12th the final permission for the star-up

contribution and dedication to the neutron

and following routine operation of FRM-II Reactor in

community through Neutron News.

Garching was released. The estimate is now a period of 10 to 12 months for taking FRM-II into full operation, with the first criticality foreseen in August to September and first neutrons at the instruments due in early autumn 2003.

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Carla Andreani

RASSEGNA SCIENTIFICA Articolo ricevuto in redazione nel mese di Giugno 2003

THE ELETTRA SYNCHROTRON RADIATION LABORATORY G. Paolucci Sincrotrone Trieste S.C.p.A. S.S. 14 Km 163.5, in Area Science Park 34012 Basovizza-Trieste, Italy 1. Introduction Elettra is the Italian third generation synchrotron radiation laboratory located on the Triestinian Carso plateau.

It is built around a medium energy electron storage ring operated between 2 and 2.4 GeV. The Elettra beamlines cover a wide energy range, from the far infrared to the hard x-rays, as the photon energy ranges between 2 meV and 40 keV, i.e. wavelengths between 0.6 mm and 0.3 Å.

The facility is operated by the Sincrotrone Trieste public no profit company, which also built the accelerator system and some of the beamlines. Other beamlines are built in collaboration with external partners from different scientific institutions, both Italian and from other countries.

In addition to the synchrotron radiation activity, Elettra hosts several support and complementary laboratories, which makes it a multidisciplinary Research and Service center, competitive at the international level by employing advanced micro/nano analytical, photolithographic and radiographic techniques. Researchers at Elettra are active in fields as diverse as genomics, pharmacology, biomedicine, catalysis and chemical processes, microelectronics and micromechanics.

This wide range of applications makes Elettra an international crossroad where researchers, coming from different countries and disciplines and from academic and applied research, interact and exchange in a competitive, yet friendly, atmosphere, producing new knowledge and training junior researchers. Training of younger generations of scientists and engineers for research and industry is indeed one of the missions of the Sincrotrone Trieste public company. Laboratories like Elettra constitute the backbone of the growing network of European centers of excellence, helping the integration and growth of EU research and culture. Moreover, Elettra being located on the border between the existing and new Member States of the EU, is particularly active in the construction of EU’s rich fabric of cultural and economic exchange with the Center East.

In this paper we will describe the characteristics of the laboratory as a whole, the access policy and future plans.

No details will be given on the specific beamlines: potential users interested in a particular beamline or set of beamlines are encouraged to visit our website and contact the beamline responsibles listed there.

2. Elettra: present Being a third generation synchrotron radiation source, Elettra is characterized by its high brilliance. Brilliance is a physical quantity defined as the number of photons per second per unit solid angle per unit area in a given bandwidth. A plot of the brilliance of a selection of photon source presently available or under construction at Elettra is shown in figure 1. A high brilliance implies that beamlines can be built so that a high photon flux is concentrated in a small spot at the sample, allowing microscopy, high resolution or high flux measurements.

Given this characteristic of the sources, a number of beamlines have been designed to make the best possible use of Elettra. The beamlines at Elettra have been de-

Fig. 1. Plot of the brilliance of some photon source of Elettra: the bending magnets, the existing multipole wiggler used for x-ray diffraction and small angle x-ray scattering (W14), the superconducting wiggler to be used by the second x-ray diffraction beamline (SCW), the electromagnetic wiggler used by the circular polarization beamline (EEW), the 12.5 and 5.6 undulators the figure eight undulator (FEU). EUFELE is the storage ring based FEL. The four expected peak brilliances of the FERMI @ ELETTRA FEL shown on the plot correspond to various phases of the development of the project.

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signed and built by the Sincrotrone Trieste no-profit company alone or in partnership with a number of Italian and international research institutions. The role of each partner in the construction of the beamline is stated by specific formal agreements. For each beamline a group with researchers and technicians coming from all the institutions involved is formed to construct, operate and upgrade the beamline. In this way an efficient exchange of expertise among the different partners can be achieved. The group taking care of the beamline (“Gruppo di Ricerca”, or GdR) has access to typically 30% of the available beam time for in house research, maintenance and instrumentation development. The remaining 70% is allocated through a selection by an international review committee. In some cases the specific agreements with the partners require that a fraction of this time be allocated to groups of a given nationality. One of the partners is the Abdus Salam Center for Theoretical Physics (ICTP) and for that agreement a total of 1500 hours per year are allocated to groups coming from developing countries.

Presently, this represents 1.6 % of the total available beam time. Apart from these restrictions, no a priori selection is operated on the nationality of our users, which makes Elettra one of the national research infrastructures most open to international use: for example during 2002 almost 60% of the users were from outside Italy (see table 1). The opening towards the users from other countries has allowed starting several research collaborations among Elettra scientists, the international user community and the network of SR research infrastructure, leading, for example, to a number of EU founded projects.

Italy France Germany United Kingdom Austria India Switzerland Denmark Slovak Republic Czek Republic Finland Hungary Japan Sweden

347 109 94 74 33 27 16 15 15 14 14 14 11 11

Belgium USA Holland Spain Brazil Portugal Poland Russia Australia Bielorus Canada Rumania Ireland Total

8 7 6 5 4 4 3 3 2 2 2 2 1 843

Table 1. Nationality of Elettra users in 2002

The range of applications of the beamlines spans from atomic and molecular physics to life sciences and each beamline has been built having a specific application in

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mind. This means that normally they are provided with all the instrumentation set needed for the class of experiments the beamline has been built for. Moreover, support laboratories and workshops are available on site for sample preparation and treatment and for special sample handling and mounting. Presently (June 2003), there are 16 beamlines in operation and open to external users, 1 FEL line under test, 3 beamlines in commissioning phase and 6 under construction (figure 2). A beamline summary is reported in table 2, where we have indicated the source type, the institution involved and typical ap-

Fig. 2. Scheme of Elettra beamlines around the storage ring

plications. It is worth emphasizing that the applications are wider than what is indicated in the table and that potential users are encouraged to think of new applications of our beamlines, contact beamline responsibles and submit proposals in new fields: beamlines open to external users are continuously upgraded in order to meet the needs of the most advanced research.

A variety of insertion devices are installed on all the available “long” (4.5 m) straight sections on the ring: of the 11 available straight sections, 4 have planar undulators, 1 electromagnetic wiggler/undulator, 1 permanent magnet wiggler, 3 APPLE (Advanced Planar Polarized Light Emitter) undulators, 1 figure eight undulator, 1 superconducting wiggler. Each insertion device has been optimized for the required photon energy range. A recent theoretical and experimental study has shown that

RASSEGNA SCIENTIFICA

Beamline

Source

Typical Applications

Partner/other funding sources

1

TWINMIC

Short planar U

X-ray imaging for materials and life sciences

EU

2

Nanospectroscopy

APPLE U

Microscopy of magnetic materials

3

EUFELE (Free-Electron Laser)

FEL

Time resolved two color experiments

EU

4

ESCA Microscopy

Planar U

Spatial evolution of chemical reactions

Enitecnologie

5

SuperESCA

Planar U

Surface science

6

Spectro Microscopy

Planar U

2D mapping of the properties of high Tc superconductors

FIRB

7

VUV Photoemission

Planar U

Electronic structure of semiconductors

CNR

8

Circularly Polarized Light

Electromagnetic W/U

Dichroism

EU, CNR

9

SAXS (Small Angle X-Ray Scattering)

Planar W

Polymers and biological systems

Austrian Acad. of Sciences

10

XRD1 (X-ray Diffraction)

Planar W

Protein crystallography

CNR

11

Materials science relevant materials

Bending Charles Univ. of Prague

Surfaces of technologically

EU, Czeck Acad. of Sciences,

12

SYRMEP (SYnchrotron Radiation for MEdical Physics)

Bending

Phase contrast mammography and tomography

University of Trieste, INFN, Fondazione CRTrieste

13

Gas Phase

Planar U

Atoms and molecules

CNR, INFM, INSTM, Univ Roma 1

14

MCX (Powder Diffraction Beamline)

Bending (short W)

Earth and materials science

INSTM, Univ. of Trento

15

ALOISA (Advanced Line for Overlayer, Interface and Surface Analysis)

Planar W/U

Surface structures

INFM

16

BEAR (Bending magnet for Emission Absorption and Reflectivity)

Bending

Optical properties

INFM

17

LILIT (Lab of Interdisciplinary LIThography)

Bending

2D nanolithography

INFM, CNR

18

BACH (Beamline for Advanced diCHroism)

APPLE U

Strongly correlated systems

INFM

19

IRSR (InfraRed Spectroscopy)

Bending

Life and environmental sciences

INFM

20

APE (Advanced Photoelectriceffect Experiments)

APPLE U

Electronic structure

INFM

21

X-ray microfluorescence

Bending

Material science, archaeometry, traces measurements

Regione FVG

22

DXRL (Deep-etch Lithography)

Bending

High aspect ratio microfabrication

23

IUVS (Inelastic Ultra Violet Scattering)

Figure 8 U

Vibrational excitations in disordered systems

24

BAD Elph

Figure 8 U

Very high energy and momentum resolution low energy photoemission

FIRB

25

XAFS (X-ray Absorption Fine Structure)

Bending

Non crystalline materials, catalysts

ICTP

26

XRD2 (X-ray Diffraction)

Superconducting W

Protein crystallography

Table 2. Summary of the beamlines at Elettra. Beamlines shown in italic are under construction (see also figure 2). The applications in the table are just examples of what a given beamline can offer to the user community: detailed descriptions of the beamlines can be found on the Elettra website (http://www.Elettra.trieste.it) A variety of photon sources are present at Elettra, including linear and circularly polarized insertion devices. Circularly polarized light is emitted by the Electromagnetic Wiggler/Undulator (8) and by the APPLE (Advanced Planar Polarized Light Emitter) undulators (2, 18, 20). The Figure 8 undulator (23, 24) produces linearly horizontal or vertical polarized light.

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it is possible to install IDs also the “short”(1.5 m) straight sections (which were not considered as possible photon sources originally) on the ring without affecting the performance of the ring. Short undulators, for example (figure 1) can provide a gain in brilliance of about a factor 10 with respect to bending magnets. The first beamline to make use of a short undulator will be TWINMIC. The spread in types of insertion devices reflects both the variety of applications and the advances in insertion device technology and of the theory of the accelerator. For example APPLE undulators are devices which can provide linearly and circularly polarized radiation: in the linear regime they behave exactly like a planar undula-

Fig. 3. Detail of the insertion devices on section 9 of the ring, feeding the APE set of beamlines. The dipole magnet between the two undulators deviates the beam by 2 mrad, thus allowing independent operation of the two beamlines. The structure of the APPLE undulators is also apparent from the picture: each of the undulators is composed of four sets of magnets, two above and two below the electron orbit. Horizontal sliding of the “left” magnets with respect to the “right” magnets changes the horizontal component of the magnetic field and therefore the polarizaton of the emitted radiation.

ty and low heat load problems; for this reasons it is used for the inelastic UV scattering beamline which requires extremely high resolution (∆E/E~10 -6 ) and flux (http://www.elettra.trieste.it/experiments/ beamlines/iuvs/index.html). A second branch is being built for very high-resolution low energy photoemission.

We mentioned already that access to the Elettra laboratory is not restricted to particular countries or institutions: potential new users should contact the Elettra staff to gather as much information as possible on the possibilities offered by the research infrastructure for their problem. After that they should write a proposal through our Virtual User Office link (http://users. elettra.trieste.it/) following the instructions, contained there in. There are two deadlines for proposal submission per year, one on February 28th and one on August 31st for beam time allocation in the second semester of the year and the first semester of the following year respectively.

Recent measurements and technical developments performed on Elettra beamlines are described in 389 papers on international refereed journals in the years 2000 to 2002. This number is comparable to what is produced in other similar facilities and shows the presence of Elettra in the international research. Table 3 shows a breakdown of these publications in terms of research areas. The visibility of the research performed in our laboratory is further confirmed by over 100 oral and invited conference contributions, PhD and graduation theses. For details and consultation of the Elettra publication database, please refer to: http://users.elettra.trieste.it/root/plsql/ publi_mgr.startup. Since 1997 Elettra publishes each year a selection of experimental and technical achievements, the Elettra Highlights, which are available at the link http://www.elettra.trieste.it/science/highlights/ index.html.

tor, while as circularly polarized sources they are extremely valuable for the study of dichroic systems, such as magnetic systems. They allow changing the polarization in a few seconds. One of the beamlines fed by APPLE undulators is the APE project built by INFM and composed of two branches one for low energy (10-100 eV) and one for high energy (140-1500) photoemission (see also http://ape.tasc.infm.it). The two branches can be used simultaneously and independently due to a dipole electromagnet (figure 3), which bends the electron beam by 2 mrad. Horizontally deflecting mirrors further deviate the two photon beams so that the experimental stations are about 4 m apart (figure 4) and a preparation chamber could be built between them. The figure 8 undulator, (figure 5) provides only linearly polarized light (horizontal or vertical), but has the characteristic of a low high harmonic content on the axis, thus allowing to go low energies (figure 1) with very high on-axis intensi-

3. Future plans A laboratory such as Elettra must remain at the forefront of international research. For this reason the accelerator system is continuously upgraded. Several upgrades are being carried out to provide users with a stable and reliable beam. The most demanding of these upgrades is the new injector. Presently injection is performed with a 900 MeV linac. The electron energy is subsequently ramped to 2 or 2.4 GeV. A new full energy injector based on a booster synchrotron is being built. This will allow popup injection, i.e. the electron current in the ring will be constant as new electrons are injected as soon as the current decreases below a certain threshold. This operation mode is implemented on newer sources, such as the Swiss Light Source. This virtually constant intensity mode has several advantages, most notably the complete absence of thermal drifts on both the storage ring and the optical elements and the possibility of installing low

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gap ID which is presently not possible as they drastically reduce the lifetime.

In addition to the advantages for the storage ring users, the construction of the booster synchrotron will completely free the LINAC from its role as injector and we plan to use our present LINAC as the starting element of a new advanced (or 4 th generation) source: the FERMI @ ELETTRA (Free Electron laser Radiation for Multidisciplinary Investigations at Elettra) FEL. The characteristics in terms of brilliance of this source with respect to the existing sources at Elettra are shown in figure 1: we expect a gain of over 10 orders of magnitude in

brilliance. Such an increase is due to the interaction of the electron beam with the photon beam it is producing.

In order to obtain this interaction it is necessary to be able to produce compressed electron bunches as the phase delay between the beams has to be controlled better than a few fs. There are two possible schemes to start the emission process: i) the shot noise of the electron beam is amplified -the so called SASE (Self Amplification of Spontaneous Emission), ii) the oscillation is started by an external conventional laser.

Research field Number of papers Atoms molecules and Plasmas 39 Catalitic Materials-Surface Science 111 Hard Condensed Matter: Electronic and Magnetic Structure 42 Hard Condensed Matter: Structure 35 Instrumentation and Technol. Materials 31 Life and Medical Sciences 39 (excluding Crystallography) Polymers and Soft Matter 19 Protein and Macromolec. Crystallography 73 Total 389

Fig. 5. One of the two sections of the figure eight undulator installed on the storage ring.

Table 3. Papers on refereed international journals published from 2000 to 2002 with data measured at the Elettra beamlines or description of instrumentation development on the beamlines.

Fig. 4 (below). The APE set of beamlines, showing the low- (right hand side) and high-energy branches. The two experimental stations are connected to the same sample preparation chamber.

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Although the second scheme (seeded source) is less efficient and more technically demanding, because of synchronization problems, it has the great advantage for the users that the time structure and the wavelength of the emitted photons is predictable and reproducible.

As mentioned above, Elettra has already a FEL source (EUFELE), supported by the European Union, which so far has reached the shortest wavelength for a storagering based FEL (190 nm) and is normally operated at about 250 nm (figure 1). The limit of these sources is that they need optical cavities, like a conventional laser, and the reflectivity of the mirrors drops below those wavelengths. This problem is absent in a linac based FEL. Given the existing LINAC, and the expertise in setting up accelerator based user facilities, beamlines and associated advanced instrumentation, Elettra is planning to develop a 4th generation light source. In order to define the characteristics of the new source, we consulted several possible Italian users groups, as well as the prominent members of the foreign Elettra users community, in various fields of research. From their statements of inter-

est, from specific proposals from potential users and from scientists involved in the design of experimental and characterization instruments for laser pulses, a group of scientific institutions led by the Elettra laboratory formulated the FERMI @ ELETTRA project. It is centered on the clear indications for three spectral bands of highest interest: one band around 40 nm wavelength, one around 10 nm and one in the soft x-ray region around 1.5 – 1.2 nm. Potential users are strongly interested in the availability of light with tunable polarization, in very short pulses of order 100 fs, with sufficient reliability and reproducibility, in time and intensity, to perform time resolved experiments on such time scales.

The two bands centered around 40 and 10 nm will require the upgrade of our linac with a new gun, some bunch compressors and some additional minor modifications, and will be based on the seeding principle, given the demand of potential users for a predictable and reproducible photon beam. For the 40 nm line, a conventional 200 nm wavelength laser will be fed into an undulator with the first harmonic tuned to the same wave-

Fig. 6. Schematic future appearance of the Elettra site, showing the new booster injector, and the FERMI @ ELETTRA 4th generation source built starting from the existing LINAC and with its experimental hall.

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length (the modulator). In the modulator, the laser pulse and the electron bunch are carefully superposed, producing a modulation of the electron bunch density with periods corresponding to the harmonics of 200 nm, and when the modulated bunch is transferred to an undulator (the amplifier), with the fundamental tuned to 40 nm, exponential growth of the emitted power and laser action set in. The time structure of the 40 nm laser pulses will reproduce the time structure of the conventional seed laser. For the 10 nm line two seeding schemes are envisaged, one based on a conventional non-linear optical system to produce the 5th harmonic of the seed laser, which is then fed into a 40 nm modulator and then into a 10 nm amplifier; alternatively and a cascade-system whereby modulators at 200 nm and 40 nm in sequence modulate the bunch at 10 nm wavelength, before the bunch is fed into the amplifier. Simulations of the two schemes are under way. On the other hand, for the production of 1.5 to 1.2 nm radiation, the best course of action appears to be an upgrade of the linac energy to 3 GeV. This can be done on the existing site (see figure 6) by pushing backwards the gun and the starting section of the LINAC by some 200 m, and inserting all the necessary accelerating and bunch compression sections, as needed. The seeding scheme for these shorter wavelengths has not been finalized.

Some of the most exciting perspectives for experiments using the new sources are in the time structure. The availability of ultrashort (100 fs) pulses will allow many interesting time-dependent and pump-probe experiments covering the valence band (40 nm) and the corelevel spectroscopies (10-1.2 nm). However, for these possibilities to become realities, we started a substantial R&D program in instrumentation, especially concerning synchronization and timing between short pulses (the electron gun laser, the seed laser, the storage ring master

clock for the pump-probe experiments using synchrotron radiation) and detection schemes. The fact that Elettra and the FEL will be close will make this kind of experiment possible (figure 7). The development program has already started at Elettra in co-operation with INFM, where all the necessary expertise can be found.

Microscopy and imaging can take advantage of the full spatial coherence of the new sources to implement holographic schemes based on the possibility to invert coherent diffraction data of non periodic objects, for which oversampling is possible.

Following the user requests, the undulators on the FERMI @ ELETTRA source will allow operation in both linear and circular polarization regime: Presently, we envisage to use APPLE type undulators, but are also open to accept possible advances in undulator technology.

Following a specific call for proposals, in 2002, the FERMI @ ELETTRA project has been submitted to the Italian Ministry for Education, University and Research.

4. Conclusions Elettra is a lively synchrotron radiation laboratory, offering high level instrumentation and expertise to its users. We carry on continuous development in terms of machine stability, new beamlines and upgrade of existing beamlines. A new 4th generation source has been proposed to complement (and not to replace!) the existing one.

Fig. 7. Constructing a 4th generation source close to a 3rd generation storage ring allows two color experiments as depicted above. Radiation from a bending magnet or from an ID of Elettra can be focused onto a sample.

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Articolo ricevuto in redazione nel mese di Aprile 2003

THE CIRCULAR POLARIZATION BEAMLINE AT ELETTRA: STATUS AND PERSPECTIVES T. Prosperi, S. Turchini, N. Zema Istituto di Struttura della Materia-CNR, Roma, I-00133 Roma, Italy

Abstract The Circular Polarization Beamline at ELETTRA is devoted to the study of dichroic phenomena. Its source, the Elliptical Electromagnetic Wiggler, is designed for providing circularly polarized radiation both in undulator mode and under wiggler condition. The beamline covers a very broad photon energy range (5-1000 eV) by using the combination of a Normal Incidence Monochromator together with a Spherical Grazing Incidence Monochromator (Padmore-like configuration). Resolution and fluxes available at the beamline correspond to the design specification. The wide fan of possible experiments which may take advantage of using the radiation available at this beamline cannot be performed with a single specific end-station, but user owned experimental set-ups are welcome at the Circular Polarization Beamline.

Introduction The development of insertion devices able to produce circularly polarized radiation in the vacuum ultraviolet and soft-X ray regions opens the possibility of a large variety of experiments, since both the absorption and the photoemission spectra may depend on the polarization state of the incident light. Classical experiments have been performed on magnetic materials but new results may involve also non-chiral and non-magnetic compounds. The panorama of the possible experiments allowed with circularly polarized soft-x ray radiation include magnetic and natural dichroism as well as magnetic extended X-ray absorption fine structure, spin-resolved photoemission and vacuum ultraviolet ellipsometry.

As in the case of other third generation synchrotron radiation sources, also at ELETTRA a project for the production and use of circularly polarized radiation was developed. The Circular Polarization Beamline is a joint project between the Istituto di Struttura della Materia (ISM) and Istituto di Chimica dei Materiali (ICMAT), now joined into the ISM, of the Consiglio Nazionale delle Ricerche (CNR), which took care of the design and construction of the beamline [1], and Sincrotrone Trieste which was in charge for providing the insertion device and the beamline front-end. The insertion device - a novel design of an Electromagnetic Elliptical Wiggler (EEW) - was developed in the frame of a RTD project of the European Commission, involving Sincrotrone Trieste (coor-

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dinator), BESSY and MAX-lab. The EEW [3] allows to work with variable polarization state either using the first harmonic emission in the energy range from 5 eV to about 150 eV, or exploiting the continuum smooth emission of the wiggler mode from 40 eV up to 1000 eV. The beamline has been designed with the priority of preserving as much as possible the degree of circular polarization of the radiation emitted by the EEW, although for several photon energy ranges it has meant a reduction on the performances in terms of flux or photon energy resolution.

Taking into account the large variety of experiments, from solid state physics to gas-phase spectroscopy, which would need circularly polarized radiation in conjunction with the very wide spectral range covered at this beamline, the beamline policy for what concerning the experimental setup, tend to encourage the users to bring their own experimental apparatus. The beamline staff give the maximum support for the installation on the beamline. This ensure a very high rate of success of the proposed experiments. An experimental setup for soft X-ray absorption and magnetic dichroism on film and solid sample is, at present, available for the users.

Circular Polarization Beamline Electromagnetic Elliptical Wiggler The EEW was designed to provide linearly and circularly polarized radiation over a wide range of photon energies, 5-1500 eV, using both undulator and wiggler modes

Fig. 1. Photograph of the EEW in position on the storage ring.

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of operation [3,4]. The request for helicity switching led to a fully electromagnetic design which combines the horizontal and vertical periodic magnets into one opensided structure, as shown in fig. 1. In table I the main construction parameters of the device and the maximum allowed electrical parameters are reported.

Period length Total yoke length Pole gap

212 mm 3.322 m 18 mm Vertical field

Maximum field amplitude Number of poles Maximum current

0.50 T 32 160 A

Horizontal field

0.10 T 31 275 A

Table I. Main EEW parameters

Further details of the design, construction and performance of the device are given in Ref. [4,5].

The electrical parameters reported in table I correspond to the wiggler mode of operation of the insertion device.

Under these conditions the EEW operates for different values of the vertical and horizontal magnetic field providing an elliptically polarized radiation and a continuum soft x-ray emission spectrum extending from 40 eV to more than 1000 eV. In addition to the continuum, the EEW emits a spectrum of harmonics in the low photon energy side (<40eV), whose fundamental energy is at 4.5 eV when ELETTRA operates at 2.0 GeV. At high harmonic numbers (n>>10), the series of harmonics merge the continuum emission of the EEW. The degree of circular polarization changes with photon energy in the range from 40% at 8.5 eV to 80% at 575 eV. Full circular polarization condition (~90%) should be achieved when the EEW works as a pure circular undulator i.e. when the horizontal and vertical magnetic fields are equal and less than 0.1T (Bx=By<0.1T). Under these conditions the available first harmonic lies in the photon energy range between 50 eV and 150 eV. Undulator mode of operation of the EEW allows to produce, in addition to the circularly polarized radiation and in the same photon energy range, also linearly polarized radiation with the polarization vector parallel or perpendicular to the orbit plane. In fact switching off the horizontal magnetic field, linearly polarized radiation parallel to the orbit plane is produced, while switching off the vertical coils, the remaining field drive the stored electrons to oscillate in the direction perpendicular to the orbit plane emitting vertical linearly polarized radiation.

In plane linear polarization of the emitted radiation is also available in wiggler mode of operation (Bx=0;By=0.5T) of the EEW. Following the commissioning of the EEW and associated

power supplies [5], the a.c. mode of operation have been tested in order to provide a rapid switching of the polarization state between left- and right-handed for better detection of the dichroic signals. The switching of polarization state of the emitted radiation is easily achieved by reversing the horizontal magnetic field, i.e. inverting the current into the horizontal coils. At present modulation of the circular polarization between left and righthand state is available for wiggler mode of operation, by using a trapezoidal waveform which change the polarization state at 0.1Hz . The net defined polarization state duration available for measurement is about 4s. During the switching time (about 1s) dynamic correction are applied to the electron beam stored in order to reduce disturbances to the other users. The correction are applied by means of two independent coils placed at the entrance and exit side of the EEW straight section that are driven following a “fast feed forward” scheme using a pre-built experimental look-up table.

The beamline In order to make the characteristic radiation emission of the EEW available to the users, a wide photon energy range (5-1000 eV) beamline has been designed and constructed [1]. The beamline takes into account several requirements: a) small influence on the degree of polarization of the radiation emitted by the EEW, b) high photon flux, c) high resolving power. The beamline is constituted of two different monochromators which share the entrance and exit slits as well as the pre- and post-focusing optics [2] as sketched in fig 2.

One of the monochromators is at normal incidence (NIM) covering the photon energy range 5-35 eV using two, type IV, spherical gratings. The second one, that covers the energy range 30-1200 eV, is a grazing incidence monochromator (SGM), working in Padmore-type

Fig. 2. A) General layout of the beamline (side view); B) Grazing incidence configuration; C) Normal incidence configuration. Angles and distances are not in scale for graphical reasons. G’is the normal incidence grating while G represents the grazing incidence one.

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configuration, equipped with a variable angle plane mirror and four spherical gratings. Switching between the two monochromators is obtained by simply inserting or removing one mirror (M’2). The beamline accepts a maximum emission angle of (2 hor. x 1 vert.)mrad 2 of the EEW radiation that is focused in the vertical plane by means of plane (M0) and toroidal (M1) mirrors onto the entrance slit (S1). Both mirrors of the focusing optics have 2.5 deg. grazing incidence and return the radiation parallel to the orbit plane. After the exit slit (S2) the radiation is focussed at the sample position with a toroidal mirror (M3).

Grating # Gas

Transitions

Resolving power calculated measured

G1 G1

G2

G3

G4

G4

Ne

1s -> np (850 eV) O2 1s -> π∗ and Rydberg states (530 eV) N2 1s -> π∗ vibrational states (401 eV) Ar L2,3 2p -> (ns,nd) (244 eV) He Rydberg states of the N=2 series 1s2 ->(2snp+2pns) 65 eV) Ne 2s -> np (48 eV)

3300

ª3400

tion reported for the low energy gratings (G4 and G3) is due to the incomplete wiggler behavior of the EEW in this energy range which put in evidence that the emitted electromagnetic spectrum results as the summation of the discrete emission of harmonic instead of a continuum. The signature of the presence of carbon and oxygen on the optics is visible in the curves relative to G3, G2, and G1 gratings.

Photon energy (eV) Grating 45.6 65.1 401 531 531 867

G4 G4 G2 G2 G1 G1

Photon flux (phot/s/0.1 % bw/mA) 1.2 x 109 1.0 x 1010 4.0 x 107 3.2 x 107 1.0 x 108 6.0 x 107

Table III. Measured values of the photon fluxes at selected photon energies

6500

--

6000

≈7600

6000

≈4400

8500

≈8100

11000

≈11000

The photon flux avaiable on the sample, as well as the photon energy resolution, is crucial for the proper evaluation of the feasibility of a given experiment. In fig. 5 the photon energy bandwidth togheter with the corresponding value of the photon flux is plotted as a function of the entrance and exit slits width. The data reported have been measured at 245 eV (Ar L2,3 absorption threshold) and 867 eV (Ne K absorption threshold) were resolution has been determined from the Gaussian brodening obtained with a fitting procedure performed using Voigt functions while the photon flux was determined by using the double ion chamber [6].

Table II. Summary of the available resolving power for the beamline at several photon energies.

The resolution and photon flux values obtained during the commissioning of the beamline are reported in Table II and Table III respectively. The acceptance solid angle of the beamline was (1x0.3)mrad2.

Resolution data for the SGM have been determined from deconvolution of absorption spectra of noble gases taken by means of a double ion chamber as described in [6]. In fig. 3 we show the Ne and N2 absorption spectra as an example of the procedure used to determine the resolving power values.

The photon flux transmitted through the beamline as a function of photon energy with a slit aperture of 20 µm is summarized in fig. 4. The data reported have been collected with a calibrated silicon diode while the EEW was operating in wiggler mode. The strong intensity modula-

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Fig. 3. Upper panel- The vibrational states of the N2 1s -> p* transition.

The experimental spectrum (dots) was fitted with seven Voigt functions (dashed line). Lower panel- The Ne 2s-1 np Rydberg series. The full line is the result of a fit using Fano profiles convoluted with a Gaussian. The energy distance of the two last distinguishable lines (n=18 and 19) corresponds well to the Gaussian width.

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Fig. 4. Spectral dependence of the transmitted photons through the beamline using the grazing incidence monochromator. The photon fluxes are measured at sample position with calibrated silicon photodiode.

Measurements of the polarization were made using a multilayer polarimeter, developed in the framework of the RTD project of the European Commission for the EEW [7], at several photon energies between 92 and 573 eV. Fig. 6 shows the measured linear and circular polarization rates as a function of the horizontal deflection parameter (i.e. EEW horizontal current Ih) for wiggler mode.

At 92.5 eV a comparison between undulator and wiggler mode of operation is reported. In the undulator case a maximum circular polarization rate close to unit can be obtained with equal vertical and horizontal deflection parameters (Kx=Ky), whereas in the wiggler case smaller values of the circular polarization rate are obtained due to the ratio Kx/Ky always less than unit. In both cases reversing the horizontal magnetic field direction results in a change of the helicity of the radiation as expected.

The photon energy range below 40 eV is available with the characteristic discrete line spectrum emitted by an undulator. In fact even in the case of operation in wiggler mode the spectral distribution from the EEW results in the emission of discrete lines whose separation is 4.5 eV. The emitted radiation is analyzed passing through a NIM monochromator equipped with two 2400 l/mm gratings, the first gold coated and the second coated with Al+MgF2, for high (35-10 eV) and low (10-4 eV) photon energies, respectively. A simplified scanning mechanism for photon energy selection have been chosen. It consists of a simple rotation around the grating axes instead of the traditional rotation plus translation that guarantee the Rowland condition of focussing [8].

The lack of Rowland circle condition strongly reduce the maximum obtainable resolving power, due to the severe effect of defocus aberration introduced. Holographically corrected gratings are able to minimize, in a specific

spectral region, the effect of defocusing on the resolution, making resolving power comparable with that of Rowland circle mounting. In fig. 7 the absorption spectrum of He and Ne gases at the fundamental transition are reported.

The photon energy resolution at relevant energies of fundamental absorption line of He (21.2 eV) and Neon (16.7 eV) gases shows a FWHM of about ∆EHe=4meV at He line and ∆ENe=2meV at Ne absorption structure with 20 µm slit apertures. The FWHM is influenced by the photon bandpass and the contribution from the gas, which is made of the natural linewidth plus the experimental parameters such as gas pressure, effective light-path etc.. A reasonable value for the gas contribution to the FWHM could be considered of the order of 2 meV for the He line and of about 1 meV in the case of Ne. Using these consideration, from the spectra shown in fig. 7, the available resolving power is of about 6000 at 21.2 eV and 10000 at 16.7 eV. In order to verify the estimated value of the resolving power at 21 eV, the threshold photoelectron spectrum relative to the ionization transition from the Ne 2p3/2 at 21.5 eV was measured (fig.8). The applied technique uses a very narrow bandpass photoelectron

Fig. 5. Measured fluxes and bandwidths as a function of the entrance and exit slit width taken at 245 eV and 867 eV photon energy.

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analyzer (∆Ek<1 meV, courtesy dr. S.Stranges, GAPH Beamline) and allows the selection of very low kinetic energy emitted electrons (hundreds meV), i.e. edge electrons at ionization transition. The observed features in the threshold photoelectron spectra then are not very much influenced, in their width, by the detector bandpass but are mostly defined by the photon resolution.

In fig. 8 the threshold photoelectron spectra at ionization transition energy of Ne 2p3/2, at 21.5 eV, shows that the FWHM is of about 3 meV with 20 µm slits and about 2 meV with 10 µm slits. These values, neglecting the analyzer contribution, give a resolving power of about 7000 and 10000 respectively.

In the NIM range of photon energy the polarization characteristic of the beamline has been evaluated and measured at 8.4 eV by means of a MgF2 quarter wave plate.

The results shows a degree of circular polarization of the order of 30-40% depending on the mode of operation.

Recent Achievements Because of the specificity of the beamline to measure the dichroic behavior of materials, it was very important to provide a mode of operation that allows to minimize un-

certainty introduced in the dichroic spectra by the random errors of monochromator repositioning. This is especially required at the absorption edges of materials, where rapid change in the signal intensity may introduce false dichroic signal when scanning sequential absorption spectra alternating the right- and left–hand circular polarization of the photon beam. Handness switching of circular polarization is often important in the case of MCD measurements in magnetic materials where the reversing of the magnetic field in not always reproducible, but it is crucial in the case of Natural Circular Dichroism whose properties cannot be reversed by switching any external field.

The EEW could produce alternatively a right- and lefthanded circularly polarized radiation at a frequency of 0.1 Hz operating in wiggler mode. A trapezoidal waveform is generated to drive the horizontal current power supply allowing to switch between +270A and –270A producing the change of the polarization handness. After a 1s switching time, a definite polarization state remain for about 4s, during this period the measurement occurs. Due to the need of derive small dichroic signals, several measurements may be averaged in the steady

Fig. 6. Degree of circular (S3) and linear (S1) polarization available at sample position measured as a function of wiggler horizontal deflection parameter at 574 eV, 270 eV and 92.5 eV photon energies. At 92.5 eV a comparison between wiggler and undulator for the EEW mode of operation is shown. The Stokes coefficients were measured by means of a multilayer polarimeter equipped with a suitable set of multilayers for each of the analyzed photon energies.

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state period before changing to the new handness, starting a new set of measurements. The sequence may be repeated for several times until the desired signal to noise ratio is reached. The timing of the measured signals to the polarization state is controlled by a suitable reference status voltage level from the EEW power supply. The measured signal from the sample is normalized to the incident photon flux detected through the photocurrent emitted by the last mirror gold surface. Examples of the results obtained using the switching mode of acquisition is reported in fig. 9. The Oxygen K-edge in Propylene Oxide in vapor phase is reported, no evidence of dichroic behavior is expected. The detection limit is determined by the noise and depend on the statistics of the data set. The spectrum shown in fig. 9A has been obtained averaging two readings of the signals and the noise level results in a few over thousands in the difference spectrum. Fig. 9B reports the absorption and MCD spectrum at Fe L2,3 edge measured on Fe79B19Si5. The data have been obtained in residual magnetization measuring the total drain current from the sample. Single acquisition has been used for the measurement.

Fig. 7. Left panel - The He 1s –> 2p absorption line, around 21.2 eV taken with different slit apertures. Right panel- The Ne 2p –> 3s absorption line, around 16.7 eV taken with different slit apertures.

Fig. 8. Measured photon bandwidth with 20 and 10 µm of slit apertures at 21.5 eV using threshold photoelectron spectroscopy on Ne.

Experimental Results The quality of the performances of the beamline allows to exploit a large variety of experiments. From the field of magnetic material results were obtained in thin film systems relevant for applications in magnetoelectronics, such as FeNi film on sputtered NiO films. They were investigated by means of photoemission electron microscopy (PEEM) to determine the magnetic microstructure and the magnetic coupling phenomena. The element-selective magnetic information is exploited through the magnetic circular dichroism at element specific absorption edges in the soft X-rays. The obtained results [9] suggest that the domain shape and sizes found at the surface of antiferromagnetically coupled metallic multilayers has a ferromagnetic coupling contribution, presumably caused by a build-up of roughness during the growth process. The magnetic domain patterns (fig.

10) in FeNi microstructures on sputtered NiO films reflect the presence of a local exchange anisotropy, causing the phenomenon of exchange biasing or pinning of the ferromagnetic layer. The studies on the structural and magnetic properties of new magnetic materials brought the interest of the scientific community in the field of magnetic thin films such as manganites, ferrite an generally oxides with perovskite structure. The characteristics of Colossal Magneto-Resistance (CMR) and the strong enhancement of the magnetic moments induced by the reduced geometry together with the possibility of controlling the magnetic properties through the induced distortion of crystal lattice by suitable doping, make these materials of interest for technological application.

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In this frame the properties of nanocrystalline MnxFe3O (x=0, 1.18, 1.56 and x=1.9) spinel ferrite thin films x 4 were investigated by means of the X-ray Absorption Spectroscopy (XAS) and X-ray Magnetic Circular Dichroism (XMCD) at the Mn and Fe L2,3 edges. By using a theoretical model based on atomic multiplets and crystal field calculations, the structural formulae of these thin films was determined from the XAS and XMCD data and the results compared with the structural formulae of fine powders [10].

One of the most interesting recent discovery in this area of activity is an ordered double perovskite Sr2FeMoO6, with alternating Fe3+ (3d5, S = 5/2) and Mo5+ (4d1, S = 1/2) ferrimagnetically coupled ions, exhibiting substantial CMR even at room temperature. In the proposed magnetic structure, the system is expected to have a mo-

Fig. 9. A) - Oxygen K-edge measured, in vapor phase, on Propylene Oxide. The data was taken in switching mode of polarization collecting the total ion yield signal in a gas cell. B) – Fe L 2,3 –edge measured on Fe79B19Si5 metallic glass under residual magnetization.

Fig. 11. The XMCD measured at Fe 2p-edge at 77K for ordered and disordered Sr2FeMoO6. The corresponding XMCD for Sr2FeMo0.3W0.7O6 is also shown.

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Fig. 10. Top: 25µm sized square-shaped Permalloy (Ni81Fe19) frames on NiO. Dark and bright areas correspond to oppositely magnetized domains (arrows give direction of local magnetization). The encircled regions show a breakup in block-like domains. Bottom: Graphical reconstruction of the domain patterns in the top panel. Images has been recorded at the Ni L3 edge.

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ment of 4 µB per formula unit (f.u.) due to the ferrimagnetic coupling between Fe3+ 3d5 and Mo5+ 4d1 configurations. However, the observed saturation moment in this system from bulk magnetization experiments is most often found to be about 3 µB/f.u. With the help of circularly polarized light and XMCD spectroscopy we have unambiguously shown [11] that the Mo contribution to the total magnetic moment is negligible and the reduced moment observed from magnetization measurements is driven by the presence of mis-site disorder between Fe and Mo sites. In fig 11 a comparison of the XMCD results at Fe 2p edges for the disordered Sr2FeMoO6 (meltquenched Sr 2FeMoO 6), ordered (normally prepared Sr2FeMoO6) and fully ordered (Sr2FeMo0.3W0.7O6) samples is shown. It is evident from the spectra that the

scale, however, the interface coupling between AFM and FM films gives rise to various magnetic configurations, encompassing frustrated and non-collinear spin structures due to the competition between exchange couplings of opposite sign [12].

First results on Fe(001)/NiO(001) coupled layers investigated by means of magnetic circular (MXCD) and linear (MXLD) dichroism in X-ray absorption have been obtained. An extensive preliminary characterization of structure, morphology and composition, indicated that the Fe/NiO bilayers grow uniform on Ag(001) with a good epitaxial quality [13]. The investigation by means of combined XMCD and XMLD techniques turns out to be very suitable for the study of the magnetic properties TM/NiO (TM= transition metal) structures. In XMCD in

Fig. 13. XMCD at the Fe L2,3 edge for 8ML Fe as a function of the LNiO thickness.

Fig. 12. XMLD of the Ni L2-XAS for a NiO wedge after deposition of 8ML of Fe.

magnetic moment on individual Fe ions decreases remarkably with decreasing ordering.

The exchange interactions at the interface formed between ferromagnetic (FM) and antiferromagnetic (AFM) layers result in characteristic properties that find today a wide application in the construction of new magnetoelectronic devices. The technological interest is mostly due to the large magnetic coercivities and the exchange bias effect observed in these systems. On a microscopic

fact the intensities of the TM-L3 and L2 white lines relative to parallel and anti-parallel excitation are quantitatively linked to the size and direction of the spin and orbital magnetic moments[14]. On the other hand, XMLD is sensitive to the orientation of the magnetization axis[15] and is best suited for the case of AFM like NiO, since for an AFM the XMCD would vanish. It is found that different magnetic configurations can be obtained by varying either the Fe or the NiO layer thicknesses. A selected example is shown in figg. 12 and 13.

In fig. 12 it is reported the polarization dependence of the Ni L2 edge for a NiO wedge after the deposition of 8 ML Fe (θ is the angle between the surface normal and the electric vector of the linear polarized light). The insets on the left side show the θ dependence of the branching ratio of P3 and P2 peaks while the insets on the right side show the azimuthal angle dependence for θ=0° (normal incidence). As a general trend, the Fe layer lowers the Ni XMLD effect. The XMCD measurements at

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provement in the details of the CIS spectrum, opening new inside into the excitations of Oxygen atom which needs further theoretical and experimental studies.

Conclusion The Circular Polarization Beamline at Elettra is now fully operating for a wide variety of experiments as demonstrated by the proposal submitted by external users, ranging from the magnetic properties of materials and artificial structures to the chiral properties of molecules and organic compounds including low energy excitation of atoms, small molecules and radicals. The commission of the beamline has shown that the performances matches the specifications, especially for what concerning the resolution and the degree of circular polarization all over the energy range available.

Fig. 14. Constant-ionic-state (CIS) spectra of atomic oxygen recorded at θ= 0∞, at Circular Polarization Beamline fig. 14(a), and at Daresbury on BL3.2, fig. 14(b) in the 15.1- 15.5 eV photon energy region to show a comparison of resolution in CIS spectra recorded with the Daresbury and Elettra synchrotron radiation sources.

the Fe L2,3 edge reported in fig. 13 show a sudden drop of the magnetic moment of Fe. For ∆Fe equal to 8ML the drop takes places between ∆NiO =6÷8. From angle-dependent measurements (not shown here) we can rule out a possible rotation of the Fe magnetic moment. These results point to a complex interplay between Fe and NiO that has no direct correspondence on the results reported in the literature for Fe films on bulk NiO up to now.

The availability of low energy photons together with the soft X-ray beam at the same position opens new opportunities for the experiments to be performed at Circular Polarization Beamline. The same sample could be investigated comparing the information obtained from valence excitation with the chemical and site specificity offered by the core level studies investigated both in photoemission and with absorption spectroscopy.

The availability of the low photon energy range at Circular Polarization Beamline also faces the requirements for experimental activity in gas phase spectroscopy. The small dimension of the focal spot, the high flux and the narrow photon energy bandwidth has been recently exploited by using angular resolved photoelectron spectroscopy and Constant-Ionic-State (CIS) measurements on atomic Oxygen [16] in comparison with previous data obtained at Daresbury 3.2 Beamline. The improvement in resolution is reported in fig. 13 by comparing CIS spectra recorded in a limited spectral region (15.15 – 15.45 eV).

The bandwidth in fig.13(a) is 2.5mV whereas the one in fig. 13(b) is 20 mV making clearly evident the net im-

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Acknowledgments The construction of the Circular Polarization Beamline would not have been possible without the effort of a large number of people. We would like to thank all the collaborators from ELETTRA staff, colleagues from ISM/ICMAT for their support and technical assistance.

In particular we want to thank A.Derossi, B.Diviacco, F.Lama, M.Piacentini, S.Rinaldi, L.Stichauer, S.Zennaro whose participation to this project was fundamental for the development of the beamline, M. Veronese and C.Grazioli and C.Carbone whose recent collaboration is now fundamental for the activity of the group.

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R.P. Walker et al., Design of an Electromagnetic Elliptical Wiggler for ELETTRA, Proc. Particle Accelerator Conference, Vancouver, May 1997, p.3527 R.P. Walker et al., Construction and Testing of an Electromagnetic Elliptical Wiggler for ELETTRA, Proc. 1998 European Particle Accelerator Conference, Stockholm, Jun. ’98. p. 2255.

J.A.R. Samson, J. Opt. Soc. Am. 54, 1, (1964).

H.-Ch. Mertins et al., Synchrotron Radiation News 11, 42 (1998).

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C.M.Schneider,O.de Haas, U.Muschiol, N.Cramer, A.Oelsner, M.Klais, O.Schmidt, G.H.Fecher, W.Jark, G.Schonhense, J. of Magn.

Magn. Mater. 233, 14 (2001).

L.Stichauer, A.Mirone, S.Turchini, T.Prosperi, S.Zennaro, N.Zema, F.Lama, R.Pontin, Z.Simsa, Ph.Tailhades, C.Bonningue, J. Appl. Phys.

90, 2511 (2001).

S.Ray, A.Kumar, D.D.Sarma, R.Cimino, S.Turchini, S.Zennaro, N.Zema Phys. Rev. Lett. 87, 097204 (2001).

C. Leighton, M.R. Fitzsimmons, A. Hoffmann, J. Dura, C.F. Majkrzak, M.S. Lund, I.K. Schuller, Phys. Rev. B 65, 64403 (2002) P. Luches, M. Liberati, S. Valeri, submitted to Surf. Sci. (2002) G. Schultz, W. Wagner, W. Wilhelm, P. Kienle, R. Zeller, R. Frahm, and G. Materlik, Phys. Rev. Lett. 58, 737 (1987).

B. T. Thole, G. van der Laan, and G. A. Sawatzky, Phys. Rev. Lett. 55, 2086 (1985); G. van der Laan, B. T. Thole, G. A. Sawatzky, J. B. Goedkoop, J. C. Fuggle, J.-M. Esteva, R. Karnatak, J. P. Remeika, and H. A. Dabkowska, Phys. Rev. B 34, 6529 (1986).

L.J. Beeching, A.A. Dias, J.M. Dyke, A. Morris, S. Stranges, J.B. West, N. Zema, L. Zuin, Molecular Physics 101, 575 (2003).

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Articolo ricevuto in redazione nel mese di Maggio 2003

GEM: A SHINING LIGHT IN THE ISIS CROWN Paolo G. Radaelli, Alex C. Hannon and Laurent C. Chapon ISIS Facility, Rutherford Appleton Laboratory

Introduction Powder diffraction and non-crystalline materials scattering have undoubtedly been two of the best success stories of neutron scattering at pulsed sources. Time-offlight (TOF) neutron powder diffractometers are clearly very competitive with their constant-wavelength (CW) counterparts in a variety of applications, and there is a number of areas where the two types of machines are distinctly complementary. Similarly, TOF non-crystalline materials diffractometers have proven to be complementary to their CW counterparts, with clear points of strength in the study of hydrogenous materials, among others. Medium-resolution powder diffraction and scattering from liquids and amorphous solids (L&A) have broadly similar instrument requirements, and can greatly benefit from a common platform, especially in addressing “boundary” areas, such as the study of disorder in crystalline materials. In recognition of this fact, a consortium of UK universities, headed by Prof. Peter Day 1,2 (The Royal Institution of Great Britain) was formed in 1997 with the aim of developing, in partnership with ISIS, the scientific and technical case for a state-of-the-art “General Materials Neutron Diffractometer”, for the study of crystalline and non-crystalline materials at high neutron flux 3. Jointly funded by the UK Engineering and Physics Research Council and by the Japanese Institute of Chemical and Physical Research, RIKEN, the GEM proposal was rapidly put through its paces, and developed into a very ambitious project.

GEM was to replace the Liquid and Amorphous Diffractometer, LAD, on the same beamline, directly looking at a poisoned liquid methane (L-CH4) moderator, but with a primary flightpath increased to 17m for better resolution. Particularly impressive was to be the detector design (Fig. 1), based on an array of over 6500 scintillator elements, for a total solid angle coverage exceeding 4 sterad. Also noteworthy is the out-of-plane detector coverage of ±45 degrees at most angles. The light emitted by the scintillators is detected by a series of photo-multiplier tubes, conferring to the instrument its characteristic “hedgehog” shape. Although the GEM detectors and electronics were designed and prototyped “in house”, the mass production requirements of the GEM detectors far exceeded the capacity of the ISIS detector lab. Therefore, for the first time at ISIS, the GEM detectors were to

be built by external contractors. The LAD beamline was dismantled in the early months of 1999, and the GEM beamline was quickly constructed in its place during the following summer. The GEM shutter was first opened on October 12, 1999, and some of the neutrons scattered by an Yttrium Aluminium Garnet (YAG) powder sample were detected at 90 degrees by a then sparsely populated array. More and more detector modules were installed in the following 31/2 years, and the collimation, an essential part of an instrument for which low back-

Fig. 1. An early engineering design of the GEM detector and vacuum sample tank. The beam enters the instrument from the left of the picture.

grounds are required, was progressively built. At the same time, sample environment kit specifically designed for GEM was being developed and commissioned. Now that GEM is essentially completed, it seems to be a good time to review what has been accomplished thus far, and to outline some of the future challenges and opportunities awaiting us on GEM and other diffraction beamlines, presently been proposed for the second target station (TS-II) at ISIS. Instrument concept* In general, for a given maximum resolution, CW diffractometers have a higher neutron flux on the sample and a * See Appendix I for the full set of instrument parameters

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more sharply peaked resolution function near the “takeoff” angle, while TOF diffractometers have larger detector solid angles and flatter resolution curves. The latter is achieved by exploiting the polychromatic nature of the pulsed beam at a fixed scattering angle. Angles near backscattering are a natural choice, because they provides the best resolution at the intrinsic focusing condition for TOF diffractometers, where the resolution becomes largely independent of the beam divergence and sample size. However, other scattering angles are also

Incident spectrum and bandwidth GEM looks directly at a poisoned L-CH 4 moderator, without any beam optics other than a series of 6 sets of motorised jaws, distributed along the beamline to define the beam size, from a maximum of 40h×20v mm2 to a minimum of about 1h×1v mm 2. The spectral flux for GEM, plotted in Fig. 4 as a function of wavelength, peaks at about 2 Å, and is sharply cut at long wavelengths by a series of 2 choppers, which define the single-frame bandwidth to be 4.2 Å, thereby preventing

Fig. 2. GEM detector installation, as of February 2000: The complete 90degree and 20-degrees banks are visible. Neutrons travel towards the top of the picture.

Fig. 3. An example of multi-bank refinement of GEM data: multi-histogram refinement plot for Ti4O7, a moderately complex crystal structure (courtesy of E. Kopnin). The space group is triclinic (I -1), with a = 5.59446(4) b = 7.11835(5) c = 20.41873(14). All the coordinates for the 11 atoms (all in general positions) as well as the isotropic Atomic Displacement Parameters, were freely refined, yielding values that agree with single-crystal data within few error bars.

convenient: for example, background suppression is easiest near 90°, and lower angles provide the widest dspacing range. “Radical” backscattering instruments, such as the early HRPD and OSIRIS, have no CW counterpart for some applications, and represent a truly unique contribution of pulsed sources to the field of neutron scattering. Unlike L&A data, which are rarely resolution-limited, powder diffraction data collected at multiple scattering angles cannot be easily merged, because of the difference in resolution. These data need either to be kept separated or used in a combined “multi-histogram” analysis. Although Rietveld refinement codes capable of handling multi-histogram data have existed for several years, this computer-intensive and perceivably “cumbersome” technique was not routinely employed until recently. With the enormous increase in the available computing and visualisation power, however, multi-histogram refinements have finally come of age: a Rietveld refinement of a moderately complex structure, based on data from 6 histograms, each with several thousand points (Fig. 3), can converge in a matter of seconds on a fast desk-top PC. The vast detector array of GEM was specifically designed to take advantage of this newly available power.

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frame overlap. This bandwidth yields a d-spacing range of ∆d=2.1 Å in backscattering, clearly insufficient to tackle large unit cells and magnetic structures. However, the extended 2θ coverage enables GEM to collect data up to d=40 Å (Q=0.15 Å-1). At the other extreme, the GEM collimation was designed to make the best possible use of short-wavelength neutrons: good quality data have been collected up to Q=80 Å-1 (d=0.08 Å). This extended range means that GEM has an extraordinary flexibility in tackling phenomena at a variety of lengthscales.

“Flux”and resolution The count rate of a diffractometer is defined by a combination of instrumental factors, such as the incident flux at the sample position, detector solid angle and detector efficiency, as well as by the characteristics of the sample (volume and cross section for a given Bragg peak or Q point). Other important parameters in defining the overall performances are the instrument resolution and the signal-to-background ratio for reference samples. For a powder diffractometer, a useful parameter is the so-

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called “effective flux” Φeff(d), which is linearly related to the integrated intensity per second expected for a given Bragg peak at a d-spacing d by the following formula:  V • f  mhkl Fhkl 2 I[neutrons/sec] = Φeff    V0  V0

where V is the attenuation-corrected sample volume (in cm3), f is the packing fraction, V0 is the unit cell volume

Fig. 4. Spectral flux ∑ (flux per 0.1% bandwidth) on GEM at the sample position, obtained from Monte Carlo simulations. With logarithmic binning, ∑ is proportional to the number of counts per bin for an incoherent scatterer.

2

(in Å), mhkl is the reflection multiplicity and Fhkl is the square of the structure factor (in barns). The “effective flux” of GEM, and, by comparison, that of another stateof-the-art high-flux diffractometer, D20 at the ILL are plotted in Fig. 5. The same comparison is made for the instrument resolutions in Fig. 6. These data clearly illustrate the complementarity between the two diffractometers: D20 has a higher “effective flux”, particularly at the longer d-spacings. Conversely, GEM has significantly better resolution than D20 in the whole range, as well as a much larger small-d-spacing range. As one could easily predict on the basis of these data, GEM excels in producing high-quality structural data, which are suitable of full Rietveld refinements (often including anisotropic temperature factors) of crystal structures of moderate complexity (Fig. 3), as well as data suitable for Fouriertransform methods, such as pair distribution function (PDF) analysis. Data on a typical “neutron-size” sample (a few grams) can be collected in just a few minutes (a discussion of the factors limiting data collection rates on GEM is presented below). Conversely, D20 in the configuration examined above* is faster, especially in the range where magnetic peaks are observed, but can only tackle simpler structures.

Background Low intrinsic background is critical for a high-flux instrument like GEM, where the typical user expects to see weak signals from tiny samples. In these situations, the ratio between signal and background noise, rather than the counting statistics on the signal itself, is often the limiting factor. On TOF diffractometers, most of the background originates from fast neutrons that are moderated in the “blockhouse” (the instrument enclosure), filling it with a diffuse neutron “gas”. The detectors

Fig. 5. “Effective flux” comparisons between GEM (1st frame: 0.3-4.1 Å, 2nd frame: 4.1-7.9 Å) and D20. Data for GEM are the resultof Monte Carlo simulations, in agreement with measurement ofscattering for coherent and incoherent scatterers, and are summedover all the detectors. The data for D20 are an estimate based onthe published values of the flux in the medium-resolutionconfiguration (3.7 × 107) neutrons/cm2/sec, and are purely indicative.

must therefore be protected against leakage, and covered with neutron-absorbing material everywhere except along the direct line of sight to the sample. On GEM, this was achieved by constructing a set of collimating “vanes”, both inside and outside the sample tank, which consisted of a metal frame covered in “crispy-mix” -a boron carbide/resin composite with a rough surface.

Boron has a high absorption cross-section for thermal neutrons, whilst the hydrogenous resin slows down the fast neutrons so that they can be absorbed by the boron.

In addition, the detector modules were individually shielded with borated material. The measured background depends on the scattering angle and on wavelength, and is lowest near 90 degrees, where the background-equivalent total cross section is ~3×1020 barns at 1 Å (full open beam). This is equivalent to the incoherent scattering produced by 5 mg (0.8 mm3) of vanadium, enabling measurements on tens of milligram-size crystalline samples to be performed routinely (see Fig. 7). * A new high-take-off configuration for D20 is currently being tested at the ILL. In this mode, the performances of D20 are expected to be similar to those of GEM

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Hardware and software The original instrument design and the subsequent development led to a number of innovations, both in the hardware and in the software. One requirement that was identified early on was that of constructing GEM in its entirety out of non-magnetic materials, to prevent the instrument from being magnetised during high-field experiments. Furthermore, all the components sensitive to magnetic field, the photo-multiplier tubes in particular, were shielded with µ-metal, a hard (and costly) work that has now paid off with the acquisition of a 10 Tesla cryomagnet (see below) A later addition to the instrument hardware was an innovative oscillating radial collimator (Fig. 8), designed to remove the coherent and incoherent background generated by the sample environ-

Fig. 6. Instrumental resolution of GEM (1st frame: 0.3-4.1 Å). The “best” resolution at each d-spacing is plotted, and a step downwards occurs each time a new bank is in range. An estimated curve for D20 is plotted for comparison.

Fig. 7. Rietveld Refinement plot for a 2 mm2 sample of Yttrium Iron Garnet (YAG), after an overnight data collection.

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ment (which is 3 orders of magnitude greater than the intrinsic instrument background.). With its 170, 80-cm high lamellae coated in isotopic 10B and equipped with an in-vacuo oscillating mechanism, this device required over 2 years of engineering development. It has, however, worked flawlessly since its installation, and can reduce the background by as much as 3 orders of magnitude for cryostat and furnace experiments.

The software requirements for a successful operation of the GEM scientific programme are particularly stringent.

Data from almost 7000 individual detector elements, each containing 5000 time channels (a total of about 150 Mbytes), need to be stored, focussed and often analysed in a time comparable to the measuring time. Measurement on non-crystalline materials typically last several hours, even on GEM, and existing software, with appro-

Fig. 8. D. Abbley and D. Maxwell inspecting the GEM oscillating radial collimator as it was being installed in the sample tank.

priate modifications, proved to be adequate. However, completely new software was required for the crystallography programme, since the measuring times can be as short as 1 minute. To meet this challenge, we wrote the ARIEL data reduction and visualisation programme, based on the IDL language platform, which can focus and display crystallographic data on-line, and generate the required input files for Rietveld refinement (Fig. 9).

More recently, the ARIEL capabilities were expanded by a sequential Rietveld module, which analyses the data as they are produced and displays one or more of the refined parameters as a function of a sample environment variable (temperature, magnetic field, etc.). This kind of flexibility and user friendliness is crucial if GEM is to compete successfully with CW diffractometers, which have a far simpler data structure.

Sample environment Although most of the “standard” ISIS sample environ-

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ment kit can be used on GEM, a number of devices were specially redesigned, to take maximum advantage of the wide detector coverage, both in and out of the equatorial plane. Particularly welcome is the recent addition of a 10 Tesla cryomagnet, co-funded by RIKEN and the UKJoint Research Equipment Initiative. It provides high magnetic field, flawless temperature control between room temperature and 1.5 K, sorption and dilution capabilities for temperatures down to the tens of millikelvin range and, most importantly unhindered access to the whole 2θ range of GEM. Science on GEM A number of highly topical science areas were cited as prime targets in the GEM proposal. In the field of crystallography, great emphasis was placed on the projected ability of GEM to map multi-dimensional phase dia-

small samples, traditionally a weak point of neutron powder diffraction, would enable the study of a variety of advanced materials that can only be prepared in small quantities, such as those obtained by high-pressure synthesis, electrochemistry, or containing expensive isotopes. The wide Q range and the exceptional stability of the GEM detectors make it perfectly suited for total scattering studies of partially disordered crystals using the PDF method.

In the field of L&A materials, strong emphasis was placed on studies of amorphous materials in extreme conditions, such as liquid molten salts at high temperature and pressures, studies of melting phenomena, supercritical fluids etc. Also, the high flux, high stability and extended Q range of GEM was expected to provide major breakthroughs in the study of small samples, in

Fig. 9. A screen shot of the ARIEL programme for crystallographic data reduction and visualisation. The rightside window shows a colour plot of the detector response. The left-side window shows parts of the data collected from different banks. Note the difference in resolution between the diffraction patterns.

grams of many classes of materials as a function of temperature, chemical composition, pressure, magnetic field and other parameters. Perhaps for the first time, on GEM one can create maps not only of lattice parameters and fractions of coexisting phases, but also of internal structural parameters such as bond lengths, angles and anisotropic components of the atomic displacement tensor, as well as magnetic moments. As the phase diagrams of materials such as ionic magnets and superconductors become increasingly more complex and rich in exotic physical phenomena, this “imaging” capability was deemed crucial for both physics and chemistry. Real-time and in-situ studies, such as reaction kinetics, annealing, cation migration, hydration, intercalation reactions, were also identified as a key component of the GEM programme, and one that provides a perfect match to the instrument capabilities, both for basic research and for “real” materials (cements, industrial alloys, etc.)

The ability to obtain high-quality structural data on

Fig. 10. Distribution of the published papers referring to GEM data by scientific area.

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isotopic substitution experiments and in multi-component systems in general.

It is still very much early days to assess the full scientific impact of GEM, as many publications based on GEM data are just now in the process of being submitted. Italian groups have been particularly prompt in taking advantage of the GEM potential: 16% of the published GEM papers are from Italian institutions. Successful experiments were performed in all the target scientific areas, and a number of publications are already in print (Fig. 10). Clearly, GEM has demonstrated its ability to produce superb structural refinements, often comparable to

Fig. 11. In situ formation of the ferroelectric perovskite BaZn 1/3Ta2/3 O3 upon heating. The figure is a composite of about 190 runs, taken at 7 min intervals (courtesy of R.I. Ibberson; see also reference 14).

those from single crystals, with data acquisition times of the order of a few minutes or less. Also, the early promises of a much improved stability with respect to existing TOF instrumentation have been fulfilled. What follows is a brief selection, meant to illustrate the capabilities of GEM in different areas of science.

Chemistry: A variety of systems were investigated, including manganites, superconductors and other ionic compounds 4, 5 6 7-13. In these experiments, the structural and magnetic properties were typically monitored as a function of temperature for a number of compositions.

Several in situ experiments were performed on hostguest systems and on the synthesis and thermal evolution of ferroelectrics 14. As part of the latter experiment, the formation of the ferroelectric perovskite BaZn 1/3Ta2/3O3 (BZT) from its precursors was monitored in situ: Fig. 11 shows a particularly â&#x20AC;&#x153;colourfulâ&#x20AC;? presentation of the data.

Another interesting aspects of the chemistry programme on GEM in the last 3 years have been the study of isotopically enriched sample, with the aim of enhancing the contrast for particular structural features by combining data from different isotopes15, 16, and the field of molecu-

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lar magnets 17, 18. Both these applications are particularly challenging for GEM, because they entail very small samples, which, in the latter case, have low ordering temperatures and magnetic moments.

Materials science: A few materials science experiments on pyrolisis reactions19-21, crystallisation experiments, and high-temperature annealing of superalloys22 tested the current limits of the GEM data acquisition package, with collection times of the order of 30sec. Unsurprisingly, the maximum data rate is determined by how fast the large data files can be stores, rather than by the neutron flux (see below). Battery materials such as manganese

Fig. 12. Short and long-range magnetic ordering in Pr0.35(Cay,Sr1-y)0.65 MnO3. The colour scale indicated the scattered neutron intensity. On cooling, the short-range ferromagnetic ordering (diffuse scattering at long d-spacing) evolves either into long-range ferromagnetic ordering through an intermediate antiferromagnetic phase (y=0.8) or antiferromagnetic ordering (y=0.7, 0.6). The data are from the 10-degree (top) and 20-degree (bottom) banks. Dramatic structural changes are evident in the higher-angle data (reference 26).

spinels and related compounds, at different stages of the charging cycles, are now routinely studied on GEM23.

Although these studies have so far been performed ex situ (an electrochemical cell is presently being planned for GEM), they are nonetheless challenging, because the sample is typically recovered from the surfaces of an electrode and weights a few milligrams. Unusually for neutrons, we employ a 1mm diameter quartz capillary as a sample container.

Physics: many of the early GEM highlights were produced by physics research. Once again, some of these reflected the unique ability of GEM to obtain structural information on tiny samples, for example, of high-Tc superconductors synthesised in a multi-anvil high-pressure apparatus 24, 25. Phase diagram mapping studies have been undertaken by several groups. Here, GEM shines particularly in problems where magnetic ordering

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on the short and long range is associated with peculiar structural phenomena, as in the case of the Pr0.35(Cay,Sr1-y)0.65MnO3 phase diagram shown in Fig. 12 26 . The possibility of combining GEM data with higher resolution x-ray synchrotron or neutron diffraction data for a highly accurate structural refinement was also quickly recognised. An example is the solution of the CuIr2S4 low-temperature structure, which is consistent with a coupled spin-dimerisation and charge-ordering transition 27.

As an instrument at the interface between L&A and powder diffraction, GEM has demonstrated to be ideally suited for PDF studies of partially disordered crystalline materials. A fruitful line of work has been that on “pathological” crystals with large amounts of disorder, where normal crystallographic methods fail28. For example, the average and local structures of the disordered crystalline cyanides CuCN, AgCN and AuCN have recently been determined from total neutron diffraction experiments carried out on GEM 29-31. All three materials consist of strongly bonded infinite -M-CN-M-CN- chains held together by much weaker forces. It is remarkable that Bragg diffraction in isolation is incapable of yielding the correct bond lengths in these apparently simple materials. A particular point of note that in each material the metal-carbon and metal-nitrogen bond lengths are identical. Whilst the interatomic distances within the chains are very well-defined, the inter-chain distances are much less well-defined due to random displacements of the chains along the chain axes. At the opposite end of the spectrum are studies of highly ordered crystals with a small amount of disorder produced by alloying. Here, high real-space resolution (i.e., high Q) is essential to distinguish subtle differences in bond length, as shown by Peterson et al. 32 in the semiconductor series ZnSe1-xTex. More “traditional” studies on vanadium/tellurium 33, 34 and phosphate 36 35 multi-component glasses, as well as on solutions 37 are now appearing in the press.

Future challenges and opportunities The GEM beamline and detector banks will be completed by the end of 2003, with the addition of a very low angle detector (which is already built and tested, and awaits installation), and the construction of an “addendum” to the 90-degree bank, to close the gap with backscattering. Meanwhile, the development of kit designed to enable a variety of bench-top experiments to be brought to the beamline is continuing, in partnership with several user groups. There is, however, a number of challenges that need to be met to realise the full potential of GEM, particularly in the area of electronics and data handling. In many cases, sub-second data collection times would be sufficient on GEM for complete structural refinements of crystalline materials. However,

“practical” data acquisition times are of 30 sec or more, due to the need to transfer the large GEM data. We are looking forward to installing a new PC-based instrument control programme, which will work together with the already installed Data Acquisition Electronics (DAEII). The new system will not only reduce dramatically, the dead time between standard runs, but will also open up the possibility to perform truly kinetic sub-second experiments, both in the “one-shot” and “stroboscopic” modes. On a longer-term prospective, we are striving to implement on GEM the concept of a “virtual instrument”, by bringing to bear the opportunities provided by the “e-science” and robotics technologies. The GEM user of the future will be able to control remotely, from his/her home institution, all aspects of the instrument operation, including sample changes, and to process and display the data instantly.

Beyond GEM: towards the ISIS second-target station No matter how excellent GEM has demonstrated to be, instrument scientists always dream of the next instrument, which will be even better. Thinking about how to improve on GEM, three wishes naturally come to mind: better resolution, higher count rate at long d-spacing (the region of magnetic peaks) and the need to combine short-range structure with longer-range inhomogeneities for L&A materials. Understanding these inhomogeneities is often crucial to establishing why particular materials behave the way they do, so it is becoming more important to determine both types of structure in a single experiment. These wishes may be about to be realised with the construction of the second target station (TS-II) at ISIS, which is optimised for long-wavelength neutron production. Proposals are about to be submitted for three new instruments that, to a greater or lesser degree, have been inspired by GEM. The high-resolution magnetic diffractometer WISH promises an order of magnitude higher count rate at long d-spacing with even better resolution. The “radical” backscattering instrument HRPD-II will have an even better resolution than the existing HRPD, but with GEM-like count rate for some applications. Finally, the L&A diffractometer NIMROD is designed to measure both short range structure with excellent spatial resolution (<0.1Å) and intermediate range order (concentration fluctuations, density fluctuations) out to ~100Å in crystalline solids, amorphous solids, liquid mixtures, large molecule solutions, intercalation compounds, critical fluids, engineering and polymeric materials. The aim will be to measure both shortrange and intermediate-range structures so that an accurate large-scale model of the local structure can be established. Isotope substitution will be widely used. If this portfolio is approved, the future of powder and L&A diffraction at ISIS is assured for the foreseeable future.

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11

Appendix I: GEM instrument parameters

12

Moderator:

Liquid CH4, T=110 K

Primary flightpath

17 m

Choppers:

2 disks (50 Hz)+1 “nimonic” (T0, 50/100 Hz)

Single-frame bandwidth

∆λ = 4.1 Å

Q-range:

0.05 Å-1 ≤ Q ≤ 80 Å-1

d-range

100 Å ≤ d ≤ 0.1 Å

Slits:

13 14 15

6.352m/8.145m/10.265m/12.675m/ 16

15.350m/16.550m, all motorised.

Detectors

ZnS scintillators, covering a 4 sterad solid angle.

17 18 19

Bank Mean angle 2 theta

Min Angle

Max Angle

L2

Resolution DQ/Q

20 21

0

2°

1.1°

3.2°

2.8-2.9m*

5 - 10%*

1

9°

5.6°

12.5°

2.2-2.4m

4.7%

2

17°

13.8°

21.0°

1.48-2.10m

2.4%

22

3

35°

24.8°

45.0°

0.65-1.40m*

1.7 - 2%*

23

4

62°

49.9°

74.9°

1.03-1.44m

0.79%

5

92°

79.0°

104.0°

1.38m

0.51%

24

6

146°

141.9°

149.2°

1.54-1.74m

0.34%

25

7

159°

149.3°

169.3°

1.04-1.39m

0.35% 26

Collimation:

B4C vanes + oscillating radial collimator.

Sample environment:

All standard ISIS equipment + dedicated 10 T cryomagnet.

27

28

References

29

1 2 3

30

4

5 6 7 8 9 10

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J. C. Wasse, S. Hayama, S. Masmanidis, S. L. Stebbings, and N. T. Skipper, Journal of Chemical Physics 118, 7486 (2003).

DOVE NEUTRONI

INES - Italian Neutron Experimental Station Realisation of a neutron diffractometer, downstream from the TOSCA spectrometer, at ISIS (UK) Agreement CCLRC-IFAC: 001 (January, 2003) 1-Introduction Neutron Spectroscopy is one of the most powerful diagnostic techniques available to the scientific research in the field of condensed matter. This technique, widely employed among the technologically most advanced countries, is not as well spread within the Italian scientific community, as the level of the GDP (Gross Domestic Product) and the political and social weight of this country would deserve. Among the various reasons responsible for the present situation, the absence of national neutron sources available to the scientific community is one of the most serious. Indeed, the beginning of the ‘70s witnessed an absolute minimum, in Italy, of the neutron scattering activities, related to the Italian disengagement from any research activity in the nuclear energy field.

Since then, the role of CNR has been of fundamental importance in the field of the neutron scattering. First, in the mid ‘70s, a know-how core of the community was preserved thanks to the agreement between CNR and ENEA to run the instrumentation installed at the TRIGA reactor (Casaccia, Roma, Italy). Then, since mid ‘80s, a cooperation activity was started with the Rutherford Appleton Laboratory (RAL, UK), where a new generation pulsed neutron source (ISIS) was under construction. As a consequence, the downward trend for the neutron scattering activity was reversed and the Italian neutron scattering community begun to grow. The building of the PRISMA spectrometer, by ISM-CNR during the period 1985-1995, and the following realisation of the TOSCA spectrometer, by IEQ-CNR in the period 19962002, has witnessed a steady growth, both in qualitative and quantitative terms, of the Italian neutron scattering community.

Today, thanks to the joint efforts of CNR, which has established a cooperation agreement with ISIS at 5% of utilisation level, and of INFM, which has established a similar agreement at 3% level with ILL (Grenoble, France), the Italian neutron community has reached a level of maturity that compares favourably with other countries in the European Union. Nonetheless, the size of the community has not yet reached the average European level, commensurate to GDP or to the population size. It is worthwhile noting that ISIS represents the world’s most powerful pulsed neutron source, whilst ILL represents the world’s most powerful neutron research

reactor. The international situation for the Italian neutron community in the European context is also testified by the positions of Prof. F. Barocchi, who is presently Chairman of the European Neutron Scattering Association, and of Prof. A. Deriu who is the present Scientific Secretary of the ESS (European Spallation Source) Council.

Concerning the CNR involvement, it should be recalled that according to the International Scientific Co-operation Agreement signed in 1996 between CNR and ISIS (CCLRC, UK), it was stated that CNR would seek financial support for the construction of an Italian Neutron Test Station to be realised downstream from the TOSCA spectrometer (which was also taking part in the general terms of the agreement). It was agreed that some 50% of the total instrument time would be made available to the Italian scientists.

The CNR Neutron Spectroscopy Advisory Committee, has thoroughly discussed this matter. Because of the lack of national neutron sources, and considering the recent engagement of Italy, and of CNR in particular, in the Memorandum of Understanding concerning the overall design of the European Spallation Source (ESS), the Committee considered the realisation of the Italian Neutron Test Station at ISIS of strategic importance and decided to give its sponsorship to the project.

The realisation of the TOSCA project was carried out taking into account this possibility and a sufficient space was allocated to host the Italian Neutron Test Station. At the same time, the Managing Council of CNR had decided to financially support the construction of the intermediate neutron shutter between TOSCA and the Italian Neutron Test Station by extending the Strategic Project TOSCA for a 3rd year.

The TOSCA spectrometer is now completed and a new agreement, covering the period 2002-2008, has been signed between CNR and CCLRC. This agreement includes also the construction, in the near future, of a new, advanced, liquids and amorphous time-of flight (TOF) diffractometer (NIMROD). Meanwhile, the CNR Neutron Spectroscopy Advisory Committee stressed the importance of starting the realisation of the Italian Neutron Experimental Station (INES). It is worthwhile mentioning that the Committee, evidencing the importance that such a Test Station would assume in the applied-sciences (Chemistry and Materials Science, Earth Sciences, Crys-

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tallography, etc.) and aiming to an enlargement of the Italian neutron scattering community, had explicitly required that INES should be equipped with a powder neutron diffraction instrument, and urged the constitution of a national project team, chaired by M. Zoppi. At present, the Project Team members are A. Albinati and M. Catti (Milano), O. Moze (Modena), F. Sacchetti (Perugia), R. Triolo (Palermo), and the staff of IFAC-CNR involved in neutron spectroscopy (i.e. U. Bafile, M. Celli and D. Colognesi). The Project Team is open to the collaboration of the whole Italian community, represented by the Italian Neutron Scattering Association (SISN). In this context, a most valuable contribution has been given

by P.G. Radaelli (see enclosure).

It should be stressed that neutron diffraction is a very important tool for solving problems in materials science, earth science, and crystallography, in general. In addition, neutron diffraction plays an important role in technological problems where the localisation and the quantitative measurement of residual stress and strains can influence the performances of manufacts. Finally, we should never forget that neutrons are characterised by an extremely weak cross section at the atomic level and therefore their penetration length can easily reach several cm in almost all materials, including metals, where they can outperform X-rays. This makes neutrons an almost ideal probe for non-invasive, non-destructive evaluation of the microscopic bulk features of almost any material. In this field, apart from the obvious technological applications, another very important potential use of neutron diffraction is, potentially, in the field of science applied to the study of cultural heritage artefacts.

Last, but not least, the realisation of the Italian Neutron Experimental Station would constitute a training opportunity, for young researchers, on a world class pulsed neutron source instrument as well as a test station for materials and detectors. As a matter of fact, it is important to point out that several Italian research groups are involved in developing innovative neutron detectors, whilst CNR itself is engaged in the preliminary R&D activity of the European Spallation Source whose realisation is expected to be completed in some ten years time (http://www.kfa-juelich.de/ess/CUR/ESS_ currentRD.html).

2-Technical Features The TOSCA beam line looks at the ambient water moderator and therefore is rich in epithermal neutrons. However, the installation of a nimonic chopper to eliminate the very high-energy neutrons from the primary beam, with the aim of reducing the background noise, made some change in this scenario. The chopper, placed at 9.6 m from the water moderator, is set to give an opening time at 724 µs and a closing time at 10339 µs. These times are evaluat-

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ed assuming that the proton beam hits the spallation target at t=0. Recalling that ISIS operates at 50 Hz, an overall time-period of 20 ms should be taken into account. In Fig. 1 we report the flux measured by the TOSCA monitor placed at 15.75m from the water moderator.

Fig. 1. Flux measured by the TOSCA monitor placed at 15.75m from the water moderator. The two vertical lines represent the nominal opening (λ=0.298 Å) and closing (λ=4.261 Å) of the chopper..

The nimonic chopper is optimised for the best performances of the TOSCA spectrometer, which is located at 17.00 m distance from the water moderator, with no time-overlap effect. The INES position, instead, is planned to be located at 22.8 m. Adding a secondary flight path of 1.0 m, we obtain a total flight path of 23.8 m which implies time-overlap effects (see Fig. 2).

Fig. 2. Flux calculated at INES position (total flight path L=23.8m) evidencing the frame overlap effect.

A simple calculation, based on the nominal parameters, would give for INES a time-window between 5.59 ms and 20.0 ms. However, taking into account that the frame overlap can be neglected when the intensity of the slow neutrons is lower than, say, 0.1% of the fast ones,

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the effective time window can be extended down to 3.8 ms. We assume, therefore, a valid time-interval 3.8 ms < t < 20.0 ms and hence that the effective wavelengths for INES are limited between 0.632 and 3.324 Å.

Geometrical (and logistic) constraints suggest (unless a special design will be developed) that the scattering angles would be in the range between 8° and 172°. The minimum angle (8°) gives Qmin = 0.26 Å-1 and Qmax = 1.39 Å-1. Instead, the maximum angle (172°), gives Qmin = 3.77 Å-1 and Qmax = 19.83 Å-1. A radial distribution of detectors, placed at 100 cm distance from the sample position (cf. the technical notes by P.G. Radaelli, attached to the present report) imply that 3He detectors of 1cm diameter can be displaced by ≈1° from each other (centrecentre distance = 1.74 cm, i.e. sufficient to leave some space for shielding and the mechanical environment).

This implies that the second detector (at 9°) covers a Qrange [0.30 - 1.55] Å-1, while the third detector’s range (at 10°) is [0.33 - 1.73] Å-1. Thus an extended Q-interval between 0.26 and 19.83 Å-1 could be continuously covered by a set of 165 detectors placed between 8° and 172° scattering angle.

The corresponding interval in terms of d-spacing, i.e. the distance between neighbouring scattering planes in the crystal structure, is given by the Bragg’s law:

λ = 2d sinθ

(1)

where 2θ is the scattering angle, λ is the neutron wavelength, and d is the distance between two lattice planes.

Given the relation connecting the incident wavelength, scattering angle and momentum transfer Q:

4π sinθ λ the relation between d and Q is: Q =

d=

2π

(2)

terms. From the definition of the momentum transfer (Eq. 2) it is easy to obtain the relative error on Q: 2

 ∆Q   ∆d   ∆θ   ∆λ   =    =   +  Q tan θ  d     λ    2

(3)

Thus, for 2θ = 8°, d min = 4.53 Å and d max = 23.83 Å, whilst for 2θ = 172° dmin = 0.32 Å and dmax = 1.67 Å, i.e. a rather good interval for a general-purpose powder diffractometer. In fact, for the atomic elements, the average lattice parameter ranges between 2.27 Å (hcp, a-parameter of Be) to 6.13 Å (fcc, a-parameter of Xe). By contrast, complex materials may have these parameters doubled, or even tripled, but they cannot change by orders of magnitude. As a consequence, unless very peculiar periodic structures have to be studied, a neutron diffractometer like INES can give rather useful information.

As far as the resolving power is concerned, one should consider that the total flight path of INES will be rather long at 23.8 meters. In order to evaluate the resolving power it is important to take into account all the relevant

2

(4)

Here, the relative error on the wavelength (∆λ λ ) is determined by two main contributions: A) the intrinsic time-width of the neutron pulse, B) the total uncertainty on the whole flight path (L).

In both cases, the only way of decreasing the error is to make the total flight path as long as possible. In practice:

 ∆λ  2  ∆t  2  ∆L  2   =  +   λ  t L 

(5)

The first contribution is fixed by the characteristics (i.e. shape and size) of the moderator and cannot be changed. Since INES looks at the same neutron beamline of TOSCA, this contribution can be obtained knowing the design characteristics of the coupled poisoned ambient water moderator. This is expressed by a wavelength and time dependent flux-function ϕ (λ,t). In practice, the time-width of the pulse is rather sharp (2-3 µsec) for short wavelengths (epithermal neutrons). For longer wavelengths, instead, the thermal neutrons (with a Gaussian distribution) become predominant and the width of the time distribution reaches a value of the order of 40-50 µsec. At any rate, since the wavelength distribution is evaluated from the time-profile, we have to integrate the flux-function over λ in order to obtain the time-profile of the neutron pulse:

Φ(t) =

Q

2

∫

∞ 0

dλ ϕ(λ, t)

(6)

The resulting time half-width is ∆t=23 µsec and the first (time) term in Eq. 5 turns out (before squaring) between 1x10-3 and 6x10-3, depending on the wavelength. In contrast, the second term, determined by the total flight path, (also, before squaring) is ~2x10-4 (obtained by assuming similar sizes of the sample and detector, i.e. ~1 cm). It is important to point out that the effect of the total flight path is much smaller than the one determined by the time uncertainty. This means that one could use extended samples (or detectors) without deteriorating too much the resolving power of the instrument.

As far as the angular contribution is concerned, the momentum transfer uncertainty is mainly determined by the angular size of the sample and the detector, with respect to each other. By assuming again 1 cm as a standard transverse dimension for the detector, and a secondary flight path of 1 m, we obtain a ratio of 1% which, in turn, should be scaled by the angular factor θ /tan(θ),

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where 2θ is the scattering angle. This implies a large contribution from the angular factor for the forward scattering case. Going to back scattering, the angular term becomes smaller and smaller, and the resolving power is mainly determined by the other term, namely (∆λ λ) . The situation is depicted in Fig. 3.

It should be pointed out, however, that using squashed 3 He detectors, in the forward scattering banks, would drastically decrease the effect of the angular term, thus improving the resolution. This situation is depicted in Fig. 4 (note the different scale in Figs. 3 and 4, respectively).

Concerning the efficiency of the 3He detectors, we note that the available wavelength on INES ranges between 0.632 and 3.324 Å. In Fig. 5 the calculated average efficiency is reported for three types of detectors. Namely,

gard to the counting rate. It is important to consider, however, that one could imagine a design with three or four different detector banks, placed at slightly different distances from the sample, in order to cover more efficiently the solid angle and recovering a factor 3 or 4 in the black line of Fig. 6 without loss in the resolving power. Of course, the feasibility of such a solution is strictly bound to the available budget, but should be considered as a possible option at the time of the final design.

Fig. 3. Calculated resolution for secondary path 100 cm and round 3He detectors of 1 cm diameter.

Fig. 4. Calculated resolution for secondary path 100 cm and squashed 3He detectors of 2.5 mm thickness.

the round detector (10 bar, 1 cm diameter), the squashed detector (20 bar) placed with the flat side (depth 2.5 mm) or the sharp side (depth 14 mm), respectively, looking at the sample. Here average means that the round detector efficiency has been averaged by integrating over the cross section of the cylinder (see P. Verkerk, PhD Thesis, pag. 96). The squashed detectors have been approximated by a rectangular section.

However, Fig. 5 does not tell all the truth. In fact, in order to compare the various detectors, the effective solid angle should be considered. By assuming a constant height of the detectors (10 cm) and the same secondary flight path of 1 m, we arrive to the conclusions shown in Fig. 6 which gives the calculated overall efficiency reduced by the respective solid angle. It appears, as expected, that the geometrical condition with the squashed detector placed with the sharp side looking at the sample, though the most effective from the point of view of the resolving power, becomes the least effective with re-

eral-purpose needed instrument appears to be a Powder Diffractometer. A wide range of options concerning sample environment (temperature, pressure, and magnetic field) is also required, associated with such an instrument, in order to cover the largest possible potentialuser community. At present, the Italian scientific community involved in condensed matter physics consists of groups engaged in activities covering a rather extensive range of interests such as magnetism and superconductivity, structural physics and chemistry, materials, life and earth sciences, as well as engineering applications.

All these activities will gain advantages from an instrumental facility devoted to a non-destructive microscopic characterisation. Possible development topics for the community, include: - geological samples under pressure - hard magnets, magneto-resistive materials, magnetocaloric effect compounds - hydrogen storage materials and metal hydrides

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3-Scientific Applications There exists a clearly identifiable need in the Italian neutron scattering community for a General Purpose Neutron Test Station. In this context, the first and most gen-

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superconductors (both high Tc and conventional) lithium and hydrogen ionic conductors zeolites molecular magnets microscopic stress and strain in engineering components.

In all these instances, neutron diffraction has repeatedly shown its well known and extremely attractive features.

Moreover, for magnetic materials, a requirement which sets these apart from other materials is the absolute necessity to access long d spacing (up to 10-15 Å).

The two essential characteristics of the proposed General Purpose Powder Diffractometer, resolution and intensity, will be tuned to fulfil the largest requirements of the potential scientific user community. The inverse relation-

Fig. 5. Detection efficiency for the various choices of the detectors.

3

He

ship which unfortunately exists between the two will thus need to be taken into account when the final design specifications of the instrument will be set.

Assuming for INES a useful angular range between 8° and 172°, the momentum transfer available to the diffractometer will be in the interval between Q=0.26 Å-1 and Q=19.83 Å-1. For a comparison, this is similar to the Q-range available on the D4 diffractometer at ILL and is even more extended than that available on D20. This reflects in an interval, for the d-spacing, between d=0.3 Å and d=23.8 Å, i.e. fully within the majority of the requested features.

It is also extremely interesting to observe that a possible option for rotating the squashed 3He detectors in its housing, would transform INES from a high resolution, low count rate, diffractometer to a lower resolution but higher counting rate machine. It is important to point out that this change of configuration appears rather simple, in principle, and can be obtained just by a simple me-

chanical device that could be operated under computer control from the users. In practice, this option turns out to be rather expensive and its realization will depend on the amount of financing available to the project.

As a powder diffractometer, taking into account the available d-spacing range, INES could be used in many different fields. For example, it could be used in the structure determination of superionic conductors, the structural refinement of high temperature superconductors, and the structural determination of metallic alloys.

Another interesting field of application for INES would be in the earth science where it could easily resolve the crystal structures of geological samples. In the field of metallurgy, it is interesting to have direct experimental access to the quantitative amount and localisation of the

Fig. 6. Overall efficiency for the various choices of the 3He detectors, taking into account the detector’s solid angle.

residual stresses following, for example, some localised thermal treatment like soldering or brazing. Neutron diffraction can give answers to many questions. However, a field where neutron diffraction, and INES in particular, can give an extremely useful contribution is in the quantitative determination of the structure and the phase compositions of metal artefacts of archaeological origin.

A test experiment carried out recently on ROTAX has shown extremely interesting results on archaeological bronzes.

Since the research interests of the community appear to cover rather broadly areas where high resolution or high intensity is needed, the resolution and intensity characteristics of the instrument need to be tailored very carefully to these requirements. Finally, it should be taken into account that an open design, as the one proposed here, will allow using the neutron beam of INES for general testing purposes and neutron detectors development.

This is extremely important, taking into account the en-

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gagement of CNR in the Memorandum of Understanding concerning the R&D activities for ESS.

4-Structure of INES The general idea is to build the diffractometer using one half of the available space covering an interval of scattering angles between 8° and 172°, at least at a first stage.

The sample region should be rather large, so that large objects (e.g. mechanical or archaeological artefacts) could be hosted in the sample position. This, in turn, could be equipped with temperature regulation devices (CCR cryostat and furnace) and a high pressure facility in order to allow an extended experimental interval both in temperature and in pressure. Using this configuration, the other half of the available scattering angle will be available for general neutron-test purposes.

An interesting and comparatively new feature of this diffractometer will be the production of angle-dispersive profiles across the full 2q range from time-of-flight measurements. This result is expected to be obtained by the data reduction strategy of angle-dispersive, rather than conventional wavelength-dispersive, focussing. The procedure is made necessary by the limited Dl wavelength spread available, but it may present some attractive aspects particularly from the point of view of methodology. For instance, crystal structure analysis by conventional Rietveld refinement may take advantage, in some cases, from the use of angle-dispersive data. Further, the peak shape functions needed to represent Bragg profiles are affected by the choice of angle- rather than wavelength- dispersion, and a development work will be required to model such functions suitably.

A further possibility, mainly suggested by the recent test experiments on archaeological bronzes, concerns the possibility of collecting information on textures. Since mounting an extended sample on a goniometer hardly guarantees that the scattering sample remains unchanged upon rotation, it would be important to collect complementary information from a set of extra detector banks placed in the vertical plane at 90° scattering angle.

A possible option in this direction is contemplated in the enclosed preliminary design.

The possibility of accessing the fast neutrons emerging from a spallation source is of fundamental importance in instrument design. Any instrument project is usually carried out on well known concepts. However, the optimisation of the performances needs a more practical approach. As an example, we recall that during the development of TOSCA a test was carried out for a possible inverse geometry crystal analyser design of the forward scattering section [C. Petrillo, F. Sacchetti, M. Celli, M. Zoppi, and C. Checchi; An inverse geometry neutron scattering spectrometer with graphite venetian blind crystal

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analyser and a para-hydrogen filter, Nuclear Instruments and Methods in Physics A 441 (2000) 494]. This option was discarded, in the end, because of the pressures from the TOSCA international user community. However, we had shown, very clearly, that such a solution would have produced a high resolution instrument, working in an energy range that is not covered, at the moment, by the present inelastic spectrometers.

In conclusion, in the present proposal we prefigure a Test Station that, initially, will be equipped with a powder TOF diffractometer and a sample environment section leaving, however, enough space for general instrumentation testing and training of young researchers.

A-powder diffractometer The overall preliminary design is enclosed. This describes a powder diffractometer with a range of scattering angles between 8° and 172°, in the horizontal plane, with the neutron detectors placed at 1m from the sample.

Thus, a linear region of the order of 2.8 m length will be available for the detectors. Considering typical 3He neutron detector of 1 cm diameter, and allowing for some dead space for mechanical spacing and shielding (for example, displacing the detectors by 1°, one another) one could imagine to build 9 detector banks, each composed by 15 detectors, for a total of 135 detectors. Three more banks could be located in the vertical plane, at 90° scattering angle, for the sake of collecting information on textures.

Each detector bank should mechanically hold the detectors and the shielding material that, in turn, would give a partial collimation for the secondary neutrons. It is also possible to imagine that the secondary neutrons could fly in the vacuum of the sample container tank and then in a controlled atmosphere ambient (argon) before reaching the detectors. Finally, it will be important to carefully design the collimation in the secondary flight path in order to reduce the background noise or the scattering from unwanted regions of the sample (this is particularly important for large samples used in residual stress analysis and archaeological artefact characterization).

B-sample environment region This section will be designed in full agreement with the standards of the Sample Environment department of ISIS. However, we should be able to obtain a rather large volume for the sample area that will be capable of hosting particularly large samples. In this respect, based on our test experiment on the archaeological bronzes, we should provide a positioning device that allows for an almost perfect localisation of the desired portion of the sample. Some crossed beam optical device (for example, a diode-laser beam) should work rather well to this aim.

Also, we remind that the primary neutron beam should

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be in vacuum and so does the sample. Therefore, it should be possible to manipulate the sample holder using an electromechanical device operated from outside the sample container.

In addition, considering that a wide temperature range is planned for same samples, a He closed circuit cryostat and a furnace should complete the equipment of the sample environment region.

Given the rather large sample area, it will be not difficult, in the future, to equip the sample environment region with a medium-high pressure device to perform high pressure experiments. In this field, a strict collaboration with the high pressure staff of ISIS will be both welcome and necessary.

5-Scientific Support Concerning the scientific support for the present project, we remind that some research activities currently exploited at IFAC-CNR could take advantage of the Italian Neutron Experimental Station INES. Moreover, other Italian groups (either with CNR or with University Departments) will take full advantage of this instrument.

These research activities are concerning material science, at large, magnetic materials, crystallography, earth sciences, and liquid matter, in general.

CNR - Istituto di Fisica Applicata “Nello Carrara” (Firenze) 1 - Characterisation of bronze artefacts of archaeological origin (U. Bafile, L. Bartoli, M. Celli, S. Siano, M. Zoppi) With respect to a thermal neutron source, there is an intrinsic advantage in using neutron diffraction on a pulsed source. In the former case, it is necessary to move part of the experimental setup in order to change the momentum transfer. In TOF diffraction, instead, the change in the momentum transfer is obtained by changing the wavelength of the incident neutrons and a static setup can be used. The difference assumes a fundamental importance when the sample has a non-symmetric geometric shape like in ancient, archaeological artefacts.

A preliminary test, carried out on the ROTAX diffractometer, has given extremely interesting results. This novel activity, which we predict will open an extensive research field, is carried out in cooperation with the local archaeological authorities (Soprintendenza Archeologica di Firenze: M. Miccio; Museo Archeologico di Chiusi: I.M. Iozzo; Soprintendenza Archeologica di Ancona: Dr. G. De Marinis) and with Dr. W. Kockelmann (RAL).

2 - R&D activity on neutron detectors.

(P. Fabeni, G.P. Pazzi, M. Pucci, M. Zoppi,) Research activity on new scintillation neutron detectors will be of fundamental importance for the development of the peculiarities of the European Spallation Source. In

practice, the neutron detection process reduces to the absorption of the particle by a nucleus and the following decay from the excited state with a energy release to the neighbouring atoms. In this process, one of the final stages of the decay chain is the transmission of an optical signal (photons produced by the energy decay) to a photomultiplier.

One important step, necessary in the optimisation of this process, is to understand the photon propagation in the solid matrix containing the neutron absorbers nuclei, and to study the global efficiency of the process as a function of the chemical and physical composition of the matrix. To date, the most used scintillation detectors use a glass matrix. The optical workshop of our Institute has gained, in the past years, an excellent reputation in building integrated optical devices and fibre coupling of optical signals.

Physics Department “E. Amaldi”- University Roma-Tre There is deep interest in neutron diffraction techniques applied to the field of cultural heritage, in particular on ancient potteries and bones of archaeological origin.

Some small angle neutron diffraction experiments have been already carried out and more experiments are planned on ROTAX (Prof. M.A. Ricci).

An important cooperation activity could also be established with the Department of Earth Sciences, finalised to the study of materials of geological interest at high pressures.

Physics Department - University of Roma Tor Vergata Research and Development of new high-energy neutron detectors is a current important activity carried out within the TECHNI project (Prof. C. Andreani) in strict cooperation with the University of Milano-Bicocca (Prof. G. Gorini). The possibility of using a test beam line looking at the ambient water moderator will be helpful in this research area.

Physics Department, University of Perugia There is a live interest in developing diagnostic techniques for testing and quality control of crystal monochromators for neutron spectroscopy. Test of microstrip Si detectors will be also an important activity, which is carried out in cooperation with the University of MilanoPolitecnico (Prof. C. Petrillo). Moreover the INES beam line could be extremely fruitful in testing low angle inelastic scattering. This possibility can be exploited thanks to the long evacuated incoming flight path (Prof.

F. Sacchetti).

Neutron diffraction represents a very promising archaeometric tool and the knowledge of its potential in the examination of artefacts of nearly all shapes and materials, in a truly non-destructive manner, is still at a

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very early stage of exploitation by the relevant scientific community. In particular, TOF neutron diffraction will be able to provide a combined information on phase identification, phase fraction determination, microstructure, and textures of archaeological objects (Prof. R. Rinaldi).

Physics Department, University of Modena Current research interests are magnetic interactions and structures in rare-earth intermetallics, compounds and alloys, permanent magnet materials, magnetic refrigerants. Neutron powder diffraction is extensively used for the determination of the magnetic structures of these materials. Most of these measurements are performed at ISIS using the diffractometers ROTAX and POLARIS. The availability of a dedicated diffractometer will result in the development of further collaborative research projects, for example with the Department of Earth Sciences (Prof. Baraldi), on the quantitative phase analysis of ancient ceramics originating from the Mutina (Modena) area (both pre-Roman and Roman) (Prof. O. Moze).

Materials Science Department, University Milano-Bicocca Extensive research activity is being carried out on the mechanisms of ion mobility in lithium and hydrogen ionic conductors, for which a structural characterisation by powder neutron diffraction is absolutely necessary.

This activity is currently performed on standard ISIS instrumentation. The new INES diffractometer is expected to give rise to novel opportunities for testing new science and/or explorative experiments that are now of difficult realization. (Prof. M. Catti).

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Department of Structural Chemistry, University of Milano Understanding the nature of the metal-hydrogen bond is of paramount importance in the study of catalytic processes involving hydrogen transfers such as hydrogenation reactions. In particular powder diffraction at medium to high resolution will play an extremely important role in the study of the mechanism of the hydrogen adsorption in inorganic complexes, binary and ternary metal hydrides (carried out in collaboration with IFAC-CNR), by characterising the nature of the adsorbed species (e.g. H vs. H2 ) and the structural changes induced upon hydrogenation and/or doping of the starting materials. These studies require structural determinations to be carried out at various temperatures (in the range 20 â&#x20AC;&#x201C; 400K) and possibly as a function of pressure (Prof. A. Albinati).

Mineralogy Department, University of Milano Texture analysis of precious and large or heavy objects in a complete stationary experimental set-up, which is possible on TOF neutron diffraction instruments equipped with a wide 3-dimensional detector arrangements, will allow neutron structural studies beyond the current threshold level. Combined texture and microstructural analysis of metal objects can give complementary information on the different manufacturing conditions and processes. This will have important consequences for archaeometric purposes. (Prof. G. Artioli).

Marco Zoppi IFAC - C.N.R.

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ACTIONS OF CNR IN SUPPORT OF THE SCIENTIFIC RESEARCH BASED ON NEUTRONS AND MUONS SOURCES The Italian scientific community, which uses neutrons and muons as probe for the microscopic analysis of matter will be forever indebted with the Consiglio Nazionale delle Ricerche (CNR). The latter has indeed sponsored these techniques since the early 80â&#x20AC;&#x2122;s, by signing agreements for the access of the Italian researchers from CNR, Universities and Industry to the neutron facilities in Europe and supporting their research with proper actions.

The CNR has trust a small community and given the necessary opportunities and funding for a harmonic growth in all areas where neutron spectroscopy can achieve deep contributions to the Science. Indeed neutron spectroscopy, a technique that can be used in multidisciplinary research, perfectly fits the mission of a Council such as CNR. When in 1997 the Istituto di Fisica della Materia (INFM) has agreed to finance and support primarily the neutron spectroscopy research performed at reactor based international facilities (ILL and LLB), the CNR has focused its action on the Italian participation to the research performed using neutrons and muons from accelerator sources. This has been achieved through the agreement between the CNR and the Council for the Central laboratory of the Research Council (CCLRC) for the access of the

Italian researchers to the ISIS facility and by signing the MoU for the development of the European Spallation Source (ESS) project. The beam time allocated by the ISIS panels to experimental proposal submitted by Italian scientists has been over the duration of the agreement even higher than what expected on the base of the participation percentage (see Figure 1), in acknowledgment of the scientific quality of the neutron research performed in Italy. In view of these successful results CNR has recently renewed the agreement for the access to the ISIS facility for the period 2003-2006.

It has to be stressed that the action of CNR in support of the research with neutrons and muons at ISIS is not limited to the funding for access to the facility. In particular the most incisive action is the financing of specific instrumentation, designed by Italian researchers in collaboration with their partners in the UK, built in Italy and installed at the facility. Participation to instrumental development has been essential in order to increase the expertise and robustness of our community and has been a qualifying prerequisite for the Italian participation to the ESS project and the access for funding from the European Community for R&D in neutron spectroscopy.

PRISMA and TOSCA have been the first two spectrome-

Figure 1.

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ters built in Italy within the agreement with ISIS and they are available for all the users since their first operation. A particular mention has to be made of the most recent instrumental development funded within the CCLRC-CNR agreement: the Italian Neutron Station INES. An agreement between CCLRC and the Istituto di Fisica Applicata “Nello Carrara” (IFAC-CNR) for the development and utilisation of this neutron test and development area has been signed at the beginning of this year. The INES area will be used for testing and developing equipment and neutron scattering techniques and for training and development. The facility will be available to the whole of the Italian neutron scattering community as represented by the “Commissione di Studio per il Coordinamento delle Attività di Spettroscopia Neutronica del CNR”, as well as other scientists accredited by CCLRC. Access to this facility will be decided, on about an equal basis, by a separate mutual agreement between CCLRC and IFAC. IFAC shall assign, from the start of the INES experimental equipment installation programme and for the duration of this Agreement, one scientist to work at CCLRC. This scientist shall be involved in the installation and responsible for the operation of the experimental equipment on INES (see article

by M. Zoppi in this issue for a description of INES).

As in previous case, a novel instrumental development will be associated to the latest CCLRC-CNR agreement signed last year. In consideration of the high impact that instrumental development has on the scientific commu-

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nity, the CNR Neutron Committee has individuated in the NIMROD diffractometer proposed for the second target the next project of interest for the Italian community (Annex II). NIMROD, as previously PRISMA and TOSCA will be built within a collaboration between ISIS, CNR and Universities researchers.

Promotion and formation of personnel are the other two significant tasks that complete the action of CNR in support of the research performed with neutrons and muons. Among this activities I want to mention the support for travel and subsistence expenses of researchers performing experiments at ISIS and the sponsorship of the Scuola di Spettroscopia Neutronica Francesco Paolo Ricci, held every two years in Palau.

Over the last eighteen years the partnership between CNR and CCLRC for the access to the ISIS facility has been fruitful and successful, in terms of increased collaborations between Italian and British researchers on both fundamental science and R&D for instrumentation. Consequently I want to conclude this report by congratulating with ISIS staff for the recent award of British Government funding for the second target (ISIS II project) and wishing that this will be an opportunity for consolidating our partnership.

M.A. Ricci Chairman of the CNR Neutron Committeeure

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Annex I ISIS SECOND TARGET STATION PROJECT Beamline Name: NIMROD External Co-ordinator: Dr. Neal Skipper Department of Physics and Astronomy University College London, Gower Street, London WC1E 6BT. Tel: 0207 679 3526 Fax: 0207 679 1360 n.skipper@ucl.ac.uk

ISIS Contacts: Prof. Alan Soper & Dr. Daniel Bowron ISIS Facility, Rutherford Appleton Laboratory, Oxon OX11 0QX. Tel: 01235 44 5543 Fax 01235 44 5720 a.k.soper@rl.ac.uk, d.t.bowron@rl.ac.uk

This proposal requests a Near and InterMediate Range Order Diffractometer (NIMROD) as a day one instrument on the Second Target Station at ISIS. Uniquely, NIMROD will provide continuous access to particle separations ranging from the interatomic (< 1Å) through to the mesoscopic (> 300Å).

This is the characteristic dimension of fullerenes and small protein molecules, i.e. the true nanoscale. As such, the instrument will open up major opportunities for novel and timely science, in areas where the primary aim is to relate molecularlevel structure to the phase and function of materials.

The properties of many scientifically and technologically important materials arise from a subtle balance between short-, medium- and long-range interactions. Traditionally the structural correlations on these length scales are probed using separate wide- and small-angle diffraction experiments. TS-II at ISIS now provides a unique opportunity to build a diffractometer that can probe a broad range of structural correlations simultaneously. This approach makes possible the development of a coherent picture of the complex relationship between structure and properties. The rationale is to relate changes in local molecular environment to larger scale processes, such as protein folding in solution, confinement in microporous media, and phase behaviour and nucleation. In summary: • NIMROD is a unique instrument specification, which relies on the longer wavelengths of TS-II to increase the upper limit of the accessible correlation lengths, while also extracting atomic resolution from the shorter wavelengths. The instrument bridges the traditional gap between SANS and wide-angle neutron scattering, by using a common calibration procedure for all Q-scales. The data obtained from NIMROD will therefore enable the development of detailed and wellconstrained models of complex scattering systems.

• NIMROD is backed by a broad-based, internationally recognised, user community. For example, in the recent International Assessment of University Research in Chemistry in the UK (EPSRC & RSC, 2003) its use

of central neutron facilities was highlighted: “UK chemists were among the first worldwide to exploit the power of neutron scattering and synchrotron radiation to probe the behaviour of complex systems: for example, the structure and dynamics of aqueous solutions, ionic liquids, and polymers at interfaces. Work in these areas continues to be competitive internationally.”

• NIMROD will strengthen the synergy between experiment and theory, and is supported by internationally leading theoreticians. Importantly, the instrument covers length scales that are only now being viewed as accessible to atomistic computer simulations. In this context, we note that our community is responsible for recent advances in quantitative data analysis of diffraction from disordered materials. Techniques such as Reverse Monte Carlo (RMC) and Empirical Potential Structure Refinement (EPSR) allow us to produce real-space molecular models of complex systems, which can be compared directly with the experimental data.

The beneficiaries from the design of this instrument include the principle scientific disciplines, as well as more applied areas such as chemical engineering, oil and gas recovery, environmental science, renewable energy, separation technology, food science, biomaterials and pharmacology.

Scientific Case.

NIMROD will enable new science and technology wherever the molecular and mesoscale structures of disordered, or partially disordered, materials are related to their properties and function. As such, the case for this instrument underpins the core science areas of TS-II: Advanced Materials, Soft Condensed Matter, Biomolecular Sciences, and Chemical Structures, Kinetics and Dynamics. In each of these areas, potential users of NIMROD describe specific new examples relevant to their research interests. This demonstrates broad-based enthusiasm for

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the instrument, and in the context of the TS-II timescale these letters of support also provide a forward-look into growth areas served by NIMROD. It is clear that understanding of disorder over the NIMROD length scales will, in the future, become increasingly necessary to resolve major scientific and technological challenges. Core issues centre on the behaviour of biological molecules in solution, and the need to control the properties of increasingly complex liquids, glasses and composite/template materials. In each case, the subÅngstrom resolution structural data available from NIMROD are a prerequisite to detailed understanding.

Further opportunities will stem from the ability of the

and chemical phenomena in reduced-dimensions, and as a test-bed for storage, separation, release, and catalysis technology. All of these areas demand structural information on the nanometer length scales that are targeted with NIMROD. When allied with high stability detector arrays, the instrument realistically opens the possibility for routine studies of ternary and higher complexity molecular mixtures, at chemically and biochemically relevant solute concentrations.

• Biological Molecules in Solution. NIMROD will excel in structural studies of biomolecules in solution, and will supersede the currently available worldwide suite of neutron instruments. It would, for the first time, en-

instrument to exploit site-specific isotope substitution on dilute species, to first and second order difference levels.

For example, measurement of the local and mesoscopic structure of the proton environment via H/D labelling is a key to understanding hydrogenbonding and associated liquids, and in developing hydrogen storage media.

able us to relate changes in solvent structure directly to biosolute conformation. In a recent example of such work, performed on SANDALS, it was shown that pressure induced unfolding of myoglobin in aqueous solution is associated with changes in the water structure. However, this work was frustrated by the upper length-scale accessible on the instrument, a limit that would be significantly increased on NIMROD. Another example of biomolecular relevance that has recently captured the interest of the user community is the study of disaccharides, and their utilization as bioprotectants through effects such as glassification.

• Confined Fluids. A large number of natural and industrial processes depend on the properties of confined fluids, with numerous fundamental and practical questions remaining unanswered. When combined with new classes of nanoporous materials, such as MCM silicas, studies on NIMROD are likely to be pivotal: all the relevant length-scales are accessible to this

Complex and Confined Liquids Complex fluids and solutions are ubiquitous in science and technology: NIMROD offers outstanding new opportunities for the study of these systems. We anticipate major drives to understand and control the solvent mediated interactions that lead to solute association and conformational changes, and to design chemically selective solvents. Further impetus is given by the recent synthesis of nanoporous media of well-defined geometry, which opens up new possibilities in studying important effects in confined fluids. These substrates have dual status as an arena in which to investigate novel physical

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one instrument. Confinement allows one to deeply undercool liquids, and thereby to enter regions of the phase diagram inaccessible to the bulk liquid. The community will exploit this to probe the role of structural frustration and adsorption of systems as diverse as complex liquids, glass-formers, polymer melts, and hydrogen. High-resolution (sub-Ångstrom) studies of the solid-liquid interface are planned within the twodimensional pores of lamellar hosts, such as clays.

Crucial questions centre on the nature and extent of layering and solvent density. Here again, the ability of NIMROD to extend atomic resolution over hundreds of Ångstroms will lead to qualitatively new science.

enable us to study much longer chain lengths, thereby giving access to new classes of ionic liquids. For example, by increasing the amphiphilic nature of the cation, ionic liquid crystals can be formed. These have extensive mesophase ranges, and are thermally very stable.

In addition, they have potential as oriented solvents that can impart selectivity in reactions by ordering the reactants.

• Molecular Liquids. Understanding multicomponent liquids is an increasingly important aspect of modern solution chemistry. As the number and complexity of molecular species increases, the necessity to probe longer length scales rises. Often, indirect in-solution

• Electronic Liquids. Current understanding of electron localisation/delocalisation in the liquid state is hampered by a dearth of structural information over the length-scales that are crossed as one moves from an insulating (electron localised) to conducting (electron delocalised) state. The study of electronic liquids, such as metal-ammonia type solutions or liquid semiconductors, is therefore an area in which NIMROD will play a leading role. Furthermore, this instrument would allow us to probe directly the structure of the exotic species that exist in these systems, for example polarons, bipolarons, electron channels, and excitonic atoms.

• Ionic Liquids and Mesophase Systems. Room temperature ionic liquids are an environment friendly medium, of very low vapour pressure, in which one can control the selectivity of many organic reactions. To date, detailed structural studies of such liquids have been limited to short chain materials. NIMROD would

molecular effects can play a critical role in chemical phenomena such as reaction product chirality, and polymorphism. The need to understand the role of intermediate range order in solvent media is another area of rising importance. Many chemical and biochemical processes require biphasic solvents for efficient operation, especially when reaction intermediates and products have different solubilities in nonpolar or polar media. No existing neutron instrument has the range of characteristics required to probe such processes: NIMROD will therefore make a unique contribution.

Functional and Composite Materials NIMROD will probe the important structural correlations in a wide range of disordered and partially disordered solids. This will allow us to understand the relationships between structure and properties, and increasingly to tailor materials to their function. Examples in-

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clude optically and biologically active glasses, ionic conductors, advanced polymers, electrode materials, and selective molecular storage/release media. The relevance of NIMROD also extends to many advanced composites, where nanometer-scale particles or inclusions are embedded in a solid or liquid matrix. This broad class of materials includes colloidal and liquid crystal dispersions, sol-gel systems, polymer-inorganic composites, magnetic media, and intercalation compounds. ·• Porous Media and Intercalates. The proposed development of NIMROD is particularly timely for studies of this class of materials, which includes templated glasses, nanoporous polymer networks, zeolites, and graphitic and inorganic intercalation compounds. Key targets in this research are the ability to control the architecture of the host material, and the host-guest interactions. This will have impact in applications such as hydrogen storage, battery electrodes, supercapacitors, and organic and radioactive waste containment.

Again the benefits of NIMROD are clear – it will enable us to expand the host superlattice to hundreds of Ångstroms while retaining atomic resolution.

• Optical, Biocompatible, and Conducting Glasses.

Amorphous and glassy solids find increasing application across a wide range of modern technological applications. Examples include materials such as a-Si:H as an amorphous semiconductor, rare-earth doped fibre optics in amplifiers or lasers, and amorphous magnetic materials. To date, there is little information on the key functional mesoscopic length scales which relate to the correlation lengths characteristic of conduction electron mean free paths, optical and compositional inhomegeneities, voids, and the length scale of magnetic interactions. Instrumental capabilities in this area are also expected to make a significant impact in improving our understanding of the glass transition in electrolyte glasses. An exciting emerging theme is that of bio-active and bio-compatible glasses, for use in tissue growth and replacement.

• Sol-Gel Materials and Colloidal Dispersions. Sol-gel systems are finding an increasing number of applications, including optical coatings, filters, or ultra low expansion materials. In addition to local structure, low-Q data are vital to obtain information about their composition, homogeneity and mesoscopic structure, and thereby to tailor their useful properties to specific tasks. Similar arguments make NIMROD well suited for studies of those colloidal dispersions of particles such as fullerides, and metallic and ice clusters, in which the characteristic structural correlations extend to a few hundred Ångstroms.

Phase Behaviour and Nucleation A forte of NIMROD is its ability to measure, on the same

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sample and at the same time, structure over a wide range of length scales in the region of a phase transition (liquid-liquid separation, crystallisation, metal-nonmetal transition, magnetic ordering, ionic conductivity in glasses), as a function of thermodynamic parameters or composition. This information is a prerequisite for unravelling the underlying mechanisms in numerous nucleation, growth and phase separation processes.

• Clathrate formation. Understanding the formation, decomposition and inhibition of gas clathrate hydrates is critical to tackling technological challenges posed by these materials, from pipe blocking to exploiting methane resources in sediments and permafrost. There is also new interest in the control of growth and luminescent properties of semiconductor clathrates. This area of research requires structural data from NIMROD, to follow disordered guest-host and guest-host-additive systems from the early stages of formation to the evolution of crystalline structures from these amorphous phases.

• Nucleation. The ability to measure small- and wideangle diffraction simultaneously will allow us to focus on the mechanisms of a number of nucleation and growth processes, particularly the growth of crystals from pure liquids and solutions. The structure and properties of many solid materials is strongly dependent on the history of crystallisation, leading to polymorphs with widely different properties. Specific examples are that of ice formation in the presence of additives, such as sugars, and growth of metal crystals from the melt.

• Phase Behaviour of Multicomponent Liquids. There is currently no instrument that allows one to measure the mixing and phase behaviour of multicomponents.

Recent experiments point towards chemically relevant microsegregation between organic and aqueous phases, but the important length scales are missing from the picture. The instrument would also open up the new field of density-driven phase changes in liquids and amorphous solids at constant composition, and allow observation of structural transitions among surface layers of longer-chain hydrocarbons adsorbed from multicomponent solutions. The latter systems are common to many commercial detergents, as they are cheap and offer high performance. In this context, many of the restrictions on molecule size and shape would be lifted.

In summary, NIMROD is a unique instrument that bridges the accessible length scales traditionally covered by small-angle and wide-angle techniques. The instrument therefore opens up whole fields of qualitatively new science, and complements current initiatives for fabricating functional materials and nanometre scale devices.

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Outline Design Specification: The fundamental idea behind NIMROD is to obtain diffraction data over a wide range of Q, both low and high, in a single experiment. Target Station II, with its 10Hz repetition rate and optimised targetmoderator configuration, is an ideal source specification for NIMROD: • NIMROD requires an incident flight path of at least 20m, and a secondary flight path up to 7m, to achieve a sufficiently small beam divergence and penumbra that the smallest scattering angles are reached with adequate resolution. Building a shorter flight path instrument with the same Q coverage and resolution would significantly compromise the count rate at all Q values.

• As a consequence NIMROD will require a time frame of at least 68ms to access the full wavelength range, 0 10Å, in a single pulse. It is therefore ideally suited to the 100ms time frame of TS-II, without the need for the pulse removing and frame overlap choppers that would be needed on TS-I. • The low-Q capability of NIMROD is only possible by virtue of the excellent long-wavelength flux of the optimised coupled moderator available on TS-II. In the crucial low-Q region NIMROD outperforms SANDALS by a factor of up to 10 in count rate, even after taking account of the 1 in 4 pulse rate of TS-II compared to TS-I, and with better resolution. Such performance is not available on any of the TS-I moderators.

NIMROD will build on the successful SANDALS detector technology with specialised ZnS/glass sandwich detectors that are typically 70% more efficient than the equivalent 3He detector of the equivalent size. The detector electronics will follow the highly stable GEM design, which should deliver the required 0.1% stability over 24 hours as required to make full use of the available count rate on this diffractometer. This will increase the accessible concentration range for isotope difference experiments by a factor of 3 for second order difference experiments and a factor of 10 for first order difference experiments compared to SANDALS. NIMROD will view the coupled cold moderator, which produces excellent fluxes of cold neutrons. Given that the resolution requirement (DQ/Q) is ~2% for most of the Q range, and that at the low scattering angles of NIMROD the resolution is dominated by geometric considerations, the broad pulses of this moderator do not affect the resolution significantly. For disordered solids, it is proposed to build a 90° detector bank with resolution ~0.5% to significantly enhance the performance at highQ. The contributions from this higher angle bank have not been included in the performance characteristics given below, since detectors at 90° scattering angles can only be used for hydrogen-free samples.

Moderator Coupled cold Incident Wavelengths 0.05Å – 10Å Q-range 0.02Å-1 – 100Å-1 Resolution ~10%∆Q/Q, 2θ = 0.5°-5°; 2%∆Q/Q, 2θ = 12°-90°;0.5%∆Q/Q. Total Length 30m L1, L2 20m, 1-7m Flight path Straight/tapered Detectors 10 x 200 x 20mm in rows parallel to beam, and over full range of azimuthal angles, ±90°. <0.1% stability required.

Beam size 30mm wide x 30mm high Detector tank Vacuum, no beam windows visible by detectors Sample environment Standard, multi-position sample changer.

Performance The estimated count-rate and resolution of NIMROD is compared with the current SANDALS in the following graphs.

C-number measures the count rate expected for 1cm3 of vanadium placed at the sample position. The projected numbers are based on the most recent estimates of target/moderator performance for both target stations and takes account of the different frequencies of the two target stations. At low Q NIMROD outperforms SANDALS, while at high Q SANDALS is better by a factor of 2 or 3 compared to NIMROD. If a way could be found to extract an epithermal neutron beam directly from the reflector, and combine this with a guide for long wavelength neutrons, then the performance of NIMROD could be enhanced even further. In practice experience with liquids on SANDALS indicates that data beyond 20Å-1 are rarely needed, and up to this Q value NIMROD is still highly competitive.

Other Features One idea currently being investigated is the possibility of putting a Fermi chopper (and corresponding NIMONIC chopper) in the incident beam line, with a view to doing low resolution inelastic scattering measurements on some samples. Placzek (inelasticity) corrections remain an unsolved problem for hydrogen-containing materials and it could be a useful feature to have the ability to look at the inelastic response of some materials in the angle range being used by the diffraction pattern. In addition a rotating Debye-Scherrer collimator is proposed which will serve to reduce low angle backgrounds substantially. Some form of tapered neutron guide will almost certainly be needed in the incident beam to correct for gravity effects on the longer wavelength neutrons.

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Letters of support received Name Affiliation Area of interest Dr Ashok Adya University of Abertay Dundee Microporous media and electrolytes Dr. Christiane Alba-Simionesco Universite Paris-Sud Confined and supercooled liquids and glasses Dr. Paul Anderson University of Birmingham Porous media, composites and hydrogen storage Prof. Carla Andreani University of Rome Tor Vergata Hydrogenous molecular liquids, confined systems Dr Adrian Barnes University of Bristol Electronic liquids and liquid metal alloys Dr. Chris Benmore Argonne National Laboratory Functional and composite materials Dr. Daniel Bowron ISIS Hydrogen bonded liquids and solvation Dr Piers Buchanan Kings College London Superionic liquids and clathrate hydrates Prof. Eugene Bychkov Université du Littoral Functional glasses Dr. Stuart Clarke University of Cambridge Liquid adsorption and colloidal dispersions Dr. Jason Crain University of Edinburgh Phase behaviour of molecular liquids Prof. Roger Davey UMIST Nucleation and crysytallisation Prof John Dore University of Kent Liquids under confinement Dr. Sofia Diaz Moreno ESRF Molecular liquids and reaction media Dr. Luis Fernandez Barquin Universidad de Cantabria Magnetic nanaparticles and composite materials Prof. John Finney University College London Biomolecular liquids and nucleation Prof. Henry Fischer Laboratoire LURE, Paris Large molecules and biological solutions Prof Neville Greaves University of Aberystwth High temperature liquids and silicate glasses Dr. Alex Hannon ISIS Structure of glasses Prof. Jean-Pierre Hansen University of Cambridge Theory of liquids Dr. John Harding Chair, CCP5 Computer simulation of condensed matter Dr. Chris Hardacre University of Belfast Ionic liquids and nucleation Dr Simon Hibble University of Reading Functional materials and nucleation Prof. Robert Hillman University of Leicester Nanostructured and porous media Dr Diane Holland University of Warwick Advanced functional materials Dr. Uwe Hoppe Universitat Rostock

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Crystallisation of glass ceramics Dr. Kathy Johnson University of Liverpool Complex liquids and particles in solution Dr Dave Keen University of Oxford Framework structures and disordered magnetics Prof. Mike Klein University of Pennsylvania Computer simulation of complex systems Dr. Carolyn Koh King’s College London Clathrate hydrates Prof. Salvatore Magazu Università di Messina Cryoprotectants in biological solutions Prof. Robert McGreevy ISIS Disordered materials Prof. Paul McMillan Royal Institution Amorphous and nanocrystalline materials Prof. Geoff Mitchell University of Reading Functional polymers and organic materials Dr. George Neilson Bristol University Biological and electrolyte solutions Prof Bob Newport University of Kent Sol-gels and bioactive glasses Dr. Hugh Powell University of Durham Waste containment in clays Dr. Silvia Ramos ESRF Molecular liquids and ionic solutions Prof. Maria Antonietta Ricci, Chair CNR Complex liquids and disordered materials Prof. Rob Richardson University of Bristol Conformation in colloids and liquid crystals Prof. Peter Rossky University of Texas at Austin Modelling of complex and biological systems Dr Philip Salmon University of Bath Fast-ion conductors and polymer electrolytes Prof. Roger Sinclair University of Reading Poorly crystalline materials and magnetism Dr. Neal Skipper University College London Electronic liquids and confined fluids Prof. Mark Smith University of Warwick Sol-gels and bioactive glasses Prof. Alan Soper ISIS Liquids and disordered materials Dr. Jan Swensson Chalmers University Polymer composites and biomaterials Dr Matt Tucker University of Cambridge Mineral physics and radionuclide containment Dr Beau Webber University of Kent Mesostructured porous materials Prof. Adrian Wright Universiy of Reading Nanoheterogeneities in glasses Prof. Marco Zoppi CNR, Firenze Hydrogen storage and confined fluids

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BIG & SMALL INFM INITIATIVES FOR NEUTRONS DURING 2002 In his contribution to the Special Issue of this Notiziario (April 2002), Prof. Toigo – the INFM President – portrayed the role and the policy of INFM on Large Scale Facilities for Neutron Research. One year later, we are in the position to report on what happened, which initiatives and projects were supported, at both the level of large investments and disseminated support to the scientific community, and what has been the impact on the research in the field of neutron scattering. The actions undertaken by INFM in the field are sketched in the figure and are briefly reviewed here.

quota of beam time paid under the contract, and that the percentage of proposals approved by the international selection panels has typically exceeded the allowed quota reaching even levels of 5%. This data has to be taken as an indicator of the excellence of the Italian proposals that have successfully passed the panel selection. A second positive signal of the vitality of the Italian neutron community comes from the increased number of new users of the technique, which in 2002 registered a growth of about 15% compared with the period 1997-2001. It is also a promising data the wide scientific spread of the

Participation to ILL – The Institut Laue-Langevin in Grenoble, the world’s most productive neutron research centre, has just renewed its intergovernmental convention until the end of 2013. Nine countries are currently scientific partners of the ILL and INFM signed the partnership agreement for Italy in 1997. During 2002 the Italian participation to the ILL reached the level of 3.5%, thanks to a special contribution for the construction and installation of the new guide for cold neutrons on the H24 beam exit. The increased level of participation had an immediate and tangible response in the increased number of experimental proposals from the Italian community. I remark that all along the years of the ILLINFM agreement, i.e. since 1997, the proposals submitted by the Italian community have always doubled the

user community over the fields of Chemistry, Physics, Material Science and Biology.

CRGs at the ILL – An aspect of primary interest, which characterizes the INFM participation to the ILL, is the opportunity, through the CRG (Collaborative Research Group), to build, develop and run an instrument installed on the neutron beams provided by the ILL High Flux Reactor. Under the CRG, the neutron spectrometer is operated at ILL through an INFM-funded and ILL-independent management team, that also runs its own research programme made up by specific proposals from the Italian scientific community. At present, INFM is leading two CRGs, namely IN13 (CRG-A and IT/FR cooperation) and BRISP (CRG-B and IT/D cooperation), that make available 50% and 30% of the beam time, re-

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spectively, to ILL for public allocation. While IN13, an inelastic high-resolution backscattering spectrometer, is successfully running after the upgrading phase, BRISP, a thermal neutron Brillouin spectrometer, is under construction. So far, the BRISP project has been on schedule with respect to the forecast and the commissioning phase is expected to begin by the end of 2003. I want to emphasise that CRGs bring significant benefits to the Italian scientific community in a number of different ways: CRGs provide a framework within which innovative teams can operate, expanding the human and scientific resources; thanks to the reserved beam time, CRGs offer more opportunities for exploring new techniques and for carrying out difficult experiments; finally, because of the flexible organisation, CRGs provide more opportunities for training young scientists and PhD students in neutron-based research. Exploiting the benefits of running a CRG, the Italian community has the opportunity of capitalizing those human and scientific resources which are the indispensable ground for the advance and the expansion of the neutron scattering community and technique in our country.

LLB – During 2002, the collaboration between INFM and the Laboratoire Leon Brillouin in Saclay has been maintained at a cost which does not reflect the beam time effectively allocated to Italian users. This favourable situation is partly the result of long-date, well-established and very active scientific collaborations between LLB scientists and groups belonging to several Italian Universities, that carry out research programmes of common interest. I want to emphasize that the characteristic for the LLB Reactor of being a medium-size installation, joined to the existence of diffused collaboration programmes, that is the established presence of a rather large user community mostly focused on SANS (Small Angle Neutron Scattering) and Material Science (DIANE), make this source an ideal candidate for developing bilateral agreements within the European Community.

Accelerator Sources – On the recognition that future large-size neutron sources may only be based on accelerators, INFM signed the MoU for the development of the ESS project for the years 2001-2003 and contributed to the technical programme on the neutron target, by investing human resources on the ESS-Central Project Team based at the Forschungszentrum in Juelich. I wish to remark that, at present, the ISIS source is the worldleading accelerator-based source and that the Italian community has profited of the access to the ISIS infrastructures thanks to the agreement signed by CNR and ISIS and established since 1985. Through EU funding under FP-5, and now FP-6, programmes, INFM has contributed to the construction of advanced instrumentation installed at ISIS and has promoted research projects

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based on ISIS instruments by appointing young scientists under post-doc and contract positions.

Personnel – One of the major goals of the INFM policy in support of the neutron research has been the appointment of qualified young researchers, in schedule with the planned development programme. During 2002 and beginning 2003, five new researchers have been appointed to work on the CRGs projects and INFM can now count on seven researchers involved in the development of IN13 and BRISP. Support – Among the small-budget initiatives of INFM, that however have a primary impact on the growth of the neutron community, are the numerous support & promotion programs among which I want to recall the yearly grant for neutron-oriented PhD projects, the financing of research stages for degree students at the major neutron installations, the financial support to the users of ILL and LLB during the execution of the experiments, the awards for the finest thesis and PhD thesis in the field of fine structure of matter investigated by neutron techniques. During 2002, INFM contributed, together with CNR, to the organization of the VI-edition of the national neutron scattering school in Palau.

As a final comment, I want to bring to the attention of the reader the evidence of a lively community of Italian researchers which make use of the neutron techniques, and whose scientific necessities are still not completely covered by the complementary and different international agreements managed by INFM and CNR.

C. Petrillo Chairman of the NFM Neutron Committee

ATTIVITA’ ITALIANA

STATO DELLA COOPERAZIONE ITALO-AUSTRALIANO SUI LABORATORI DI LUCE DI SINCROTRONE Recentemente il Governo di Victoria ha programmato la realizzazione del primo sincrotrone australiano che comporterà sicuramente una svolta storica nella ricerca australiana ed in particolare nel campo della fisica dei materiali. L’iniziativa raccoglie le esigenze di ricercatori e scienziati delle università e dei centri di ricerca australiani, i quali, principali attori dello sviluppo congiunto di piani nazionali di ricerca di base ed applicata, intendono, grazie al nuovo laboratorio, sviluppare maggiormente attività di ricerca di tipo precompetitivo.

In questa logica, l’Ufficio Scientifico di questa Ambasciata ha ritenuto opportuno investire in una attività di cooperazione scientifica e tecnologica fra i due Paesi.

questa Ambasciata in collaborazione con il Governo di Victoria, il Commonwealth Department of Education Science and Training di Canberra, Australian Academy of Technological Sciences and Engineering, il CSIRO e La Trobe University di Melbourne.

Tale iniziativa è il risultato di un’azione maturata nel corso della Mostra Convegno IATICE di Melbourne lo scorso marzo ed, in particolare, durante un incontro tra il Laboratorio di Luce di Sincrotrone Elettra di Trieste, le Università La Trobe e Monash di Melbourne ed il CSIRO (Department of Manufacturing Science & Technology). Da tale incontro é nata una prospettiva di collaborazione che coinvolge diverse

versità di Roma Tor Vergata, Dott.

Lorenzo Avaldi del CNR (Istituto di Metodologie Inorganiche e dei Plasmi di Roma), Dott. Giorgio Paolucci Direttore della Divisione Sperimentale del Laboratorio Elettra di Trieste e dal Laboratorio Elettra la Dott.ssa Giuliana Tromba, il Dott. Kevin Prince e il Dott. Andrea Goldoni.

Alla conferenza hanno partecipato circa quaranta ricercatori e docenti delle principali università e centri di ricerca australiani che operano nel settore della fisica in generale e dell’uso del sincrotrone in particolare.

Tema principale della conferenza è stato la presentazione delle attività del Laboratorio Elettra di Trieste mirato ad un confronto tra metodologie e strumenti sviluppati, nell’ambito di laboratori di sincrotrone, nelle seguenti aree di ricerca: - Spettroscopia di nuovi materiali e in fase gassosa; - microscopia per nanotecnologie, biologia e scienze ambientali; - radiografia ed immagini di riscontro utilizzate in ambito medico; - litografia a raggi x.

Numerosi sono stati gli interventi finalizzati a individuare aree strategiche di comune interesse che sfruttano soprattutto le potenzialità della struttura italiana; rilevante é stato, inoltre, l’interesse australiano nel collaborare con l’Italia sia nella sua componente scientifica e tecnologica che imprenditoriale.

1. Conferenza Italo-Australiana "Future Directions in Spectroscopy and Imaging with Synchrotron Radiation" Dal 2 al 5 febbraio scorso si è tenuta a Lorne (cittadina nel Victoria), la Conferenza "Future Directions in Spectroscopy and Imaging with Synchrotron Radiation", promossa ed organizzata dall’Ufficio Scientifico di

Università ed alcuni centri di ricerca dei due Paesi e che vede, nel workshop di Lorne, il momento di confronto finalizzato all’avvio di una proficua attività.

La delegazione Italiana era costituita da: Prof. Fulvio Parmigiani dell’Università Cattolica di Brescia, Prof.

Maria Novella Piancastelli dell’Uni-

2. Conferenza Australiana "Australian Synchrotron Users Workshop" La conferenza di Lorne è stata programmata nel periodo succitato per consentire ai ricercatori italiani di partecipare anche al workshop organizzato dal Governo di Victoria dal titolo "Australian Synchrotron Users Workshop" tenutosi a Melbourne

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ATTIVITA’ ITALIANA

dal 29 al 31 gennaio u.s.. Infatti, il Governo di Victoria ha programmato la realizzazione del primo sincrotrone australiano e il convegno di Melbourne è stato organizzato al fine di informare l’intera comunità scientifica australiana delle specifiche del nuovo "laboratorio di luce" e le relative nuove opportunità scientifiche e tecnologiche che ne deriverrebbero.

La realizzazione del "Laboratorio di luce" nasce dalla necessità di effettuare esperimenti nei settori della biologia, della geologia, della fisica e della farmaceutica che fino ad oggi sono condotti presso altri centri internazionali quali: APS (Advanced Photon Source) in USA, Spring8 in Giappone, Hsinchu in Taiwan e Bessy in Germania.

L’evento di Melbourne, a cui hanno partecipato oltre 300 fra scienziati, ricercatori, esperti internazionali ed imprenditori dell’industria high tech del settore, è stato aperto dal Premier dello Stato del Victoria Steve Bracks e dal Ministro per l’Innovazione John Brumby. La conferenza è stata organizzata dalla "Australian Synchrotron Team", organismo preposto, per conto del Governo di Victoria, alla gestione della realizzazione del nuovo sincrotrone, dall’attuale fase di progetto alla costruzione del laboratorio.

Nel corso dei tre giorni si sono evidenziate e discusse le opportunità che il nuovo Centro di ricerca potrà garantire, in particolare nelle seguenti aree tematiche: - cristallografia di proteine; - biofisica, in particolare per lo studio di proteine legate alla patologia dell’Alzheimer, ed in generale alle malattie muscolari; - radiografia ed immagini di riscontro utilizzate in ambito medico; - nuovi materiali, nanotecnologie, semiconduttori, litografia e micromeccanica, nuove memorie per computer, etc; - scienze ambientali, analisi dell’inquinamento, e del suo effetto sulle

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specie vegetali; - scienze della terra, geologia, chimica dei minerali etc.

Il progetto del sincrotrone a Melbourne attualmente può contare su un finanziamento approvato dal Governo di Victoria di circa 157 milioni di dollari Australiani a cui si aggiungeranno circa 50 milioni di A$ dalle Università del Victoria e un ulteriore finanziamento, non ancora definito, dal Governo Federale di Canberra. Il Laboratorio sarà realizzato nei pressi della Monash University a circa 10 Km dalla City e sarà operativo entro il 2007.

3. Conclusioni In questo contesto è stato ritenuto opportuno che il Laboratorio Elettra di Trieste, ritenuto il centro di eccellenza italiano nel settore, potesse non solo partecipare alla presentazione del sincrotrone australiano ma che potesse presentare la sua facility alla comunità scientifica australiana ed, in particolare, che potesse essere considerato come modello per il nuovo Laboratorio di sincrotrone di Melbourne.

In effetti dal punto di vista scientifico, l’impressione generale è che la ricerca australiana nei campi oggetto del workshop di Lorne soffra di un ritardo rispetto al panorama internazionale ed anche a quello italiano, dovuto all’assenza di un’infrastruttura di ricerca come Elettra e non colmato dalle ridotte esperienze dei ricercatori australiani in altri paesi.

Questo porta ad una scarsa definizione dei progetti da implementare sulla nuova macchina australiana e quindi l’intervento della comunità scientifica italiana, in particolare dal laboratorio Elettra, potrebbe portare loro un grande beneficio.

Anche dal punto di vista tecnologico-imprenditoriale sarebbe necessario un intervento di ditte altamente qualificate, come quelle cresciute con l’esperienza del Laboratorio Elettra e quindi, come

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richiesto dagli australiani, sono state individuate, e riportate nei proceedings, alcune imprese italiane che operano nel settore del sincrotrone e pertanto inserite nel contesto delle attività del Laboratorio Elettra.

A conclusione dei due eventi è stato istituito un gruppo di lavoro italo australiano che consentirà la programmazione di alcune attività di cooperazione, quali la ricerca di finanziamenti per scambio di esperti e di studenti e, in particolare, la verifica, nelle rispettive realtà locali (Stato di Victoria, Regione Friuli Venezia Giulia, Università, Centri di Ricerca ed imprese ad alto contenuto tecnologico del territorio), della possibilità di creare a Melbourne, in concomitanza della realizzazione del sincrotrone australiano, una joint venture italo-australiana finalizzata a fornire consulenza nel settore.

Robert Leckey Giorgio Paolucci Nicola Sasanelli

PROGETTO E.S.S.

ESS: THE DISCUSSION CONTINUES The ESS project is going through a difficult phase, however the discussion continues on the political level across Europe. Several critical political events happened in this period, causing the change in the timing and pace of the project.

The assessment by the German Science Council ranked the ESS behind two other major investments in infrastructure in Germany, and aired some rather critical comments about the use for neutrons in the future.

The latter has been strongly criticized in the press and the WR has declared its readiness to re-evaluate ESS. But while the Bonn documents, which are the product of a huge effort of a large number of the best scientists throughout Europe, have not been evaluated at all, it seems that a full new proposal is required for such a re-evaluation. In December 2002 at a meeting between the WR, the secretaries of state of the three German Länder involved and the German partners FZJ and HMI agreed on a procedure whereby the WR would first assess the science case, based on a number of specific questions, and only later discuss site aspects of the potential German sites. The questions received by the ESS last January 2003, however, are not specific at all, deal with site aspects as well, and are in fact virtually the same as the questions received in 2001. As a consequence, the situation with respect to a new evaluation is still very much open. There are pressure for a fast re-assessment of the ESS project, but this is still debated within the German partners.

The European long and medium term need for neutron scattering facilities was first class large scale facilities to be discussed by a newly formed European forum ESFRI (European Strategy Forum on Research Infrastructures). To prepare for this

discussion ESFRI created a Working Group on Neutron Sources to analyse the european situation and specifically look at three specific scenarios for the future provision of neutrons: 1. Build ESS with two 5 MW target stations as proposed in Bonn 2002.

2. Build the 5 MW long pulse target station first.

3. Build either a 1 MW upgrade of the short pulse ISIS facility or a 1 MW version of AUSTRON. In all of the above mentioned options the Millennium Programme at ILL and the second target station at ISIS, were considered as part of the baseline option. The Working Group Report on neutrons clearly demonstrated that the full ESS or a staged approach starting with the long pulse Target Station were affordable and the most cost-effective solutions. Other scenarios would bring Europe in a competitive, but not leading position relative to the

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US and Japan until they would realise their plans for upgrading their facilities, which could start immediately after the end of construction.

On January 16, 2003, ESFRI met to discuss the results of this study.

There was basically no discussion of the report, as the representatives of Germany and UK expressed their unwillingness to support the ESS in the short term. The meeting was instead devoted to prepare the following recommendations: ESFRI: (a) notes that there exists a “baseline” option, which has potential for growth through a series of plans for facility upgrades, to support scientific activities in the medium term; (b) understands that there is not sufficient support from the Member States for the realisation of a next generation European Spallation Source in the short term; (c) recognises that a major new Euro-

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PROGETTO E.S.S.

pean neutron facility is necessary in the long term, therefore a decision is necessary in the medium term; (d) therefore draws attention to the need for continuing work on the scientific and technical capabilities to underpin future developments in this and related areas; (e) the final report of the WGNS will be made available to the public (e.g. through the ESFRI website).

The ESFRI meeting had direct consequences on ESS. The Council of the European Spallation Source met in Zürich on January 22, 2003, to discuss the implications of these conclusions. The Council decided to reduce the technical work and concentrate efforts on political attempts to get an earlier decision. According with the new circumstances of the project, the private company ESS GmbH, thought to facilitate the management of the ESS project, has not been established.

In Germany the three Länder interested to host ESS, North-Rhine Westfalia, Sachsen and Sachsen-Anhalt, still pursue their aims. In the federal Parliament, motions have been introduced to reproach the federal government for not being transparent and not discussing its proposals in Parliament before taking any decision. A hearing took place on April 2 in the Parliament in Berlin, where the representatives of the majority party were asked not to attend.

The Scandinavian bid is still alive and 4 Ministers of the swedish government are involved in the fight for the next generation spallation source. However, the ESS Scandinavian Consortium thinks that a period of time of some years would be the most appropriate one for a decision.

The Yorkshire bid is also alive and trying its best for having ESS at Selby, but they are now facing a strong opposition by the central government representatives, since the second target station at ISIS have been

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funded officially on April 8, 2003.

The intention of the UK authorities is not to have a new neutron source on their agenda until after the next Government Spending Review – meaning a delay of up to 5 years.

The Committee for Industry, International Trade, Energy and Research of the European Parliament will devote a session to ESS on May 22 in Brussels, where ESS representatives will describe scientifical, social, political and economical aspects of the ESS project.

In the short term, the ESS organization will assist everyone who can contribute to clarify in their country the decision making and the decisions made or not made about ESS, or more generally the ESFRI report and to press for proper assessment in the event of any decisions. That pertains to Germany, the UK but also others. In addition, ESS must prepare for how to continue if the view that there will be no short-term decision about a new major facility in Europe prevails, the evident interest is to try and limit the delay in getting a decisions as much as possible, to be involved in designing and building instruments for the most advanced facilities and to maintain the technical capabilities to build at a later time the world’s best spallation source. This requires a ‘home’ for ESS and a small organization that can liaise with politics, co-ordinate activities, and carry out the planning according to a new time schedule.

Consultations are being carried out at present to make sure that as soon as the present ESS Council will cease to exist and the new organization will take over.

Letters of support for the ESS project has been sent by the Neutron Round Table and the European Neutron Scattering Association to all the European governments and the European Commissioner Busquin. The letters want to be a clear sign of the support of the European users for the ESS, which represents the future

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of the activity in Europe and the world lead in this field. This is extremely important for the future of the young generation of european scientists, which will be most affected by these political decisions.

F. Carsughi

SCUOLE E CONVEGNI

CONGRESSO SISN Genova, 26-27 Giugno 2003

Il 26 e 27 Giugno 2003 si è svolto, presso l’Istituto Nazionale di Fisica della Materia a Genova, il Congresso SISN per la durata di quattro giornate di comunicazioni orali di 20 minuti ciascuna più una mezza giornata dedicata all’Assemblea. Durante l’Assemblea, si sono anche svolte comunicazioni di interesse e discussioni di argomenti di politica neutronica, sia nazionale che internazionale.

Presente anche una sessione Poster dedicata ai giovani con premiazione dei migliori.

Gli argomenti scelti per due mezze giornate sono stati: - Applicazioni della neutronica ai beni culturali (organizzata da Alberto Albinati: e-mail: alberto.albinati@unimi.it ) - Biofisica e neutronica (organizzata da Alessandro Paciaroni: e-mail: paciaroni@fisica.unipg.it)

Scientific Committee A. Albinati, F. Aliotta, C. Andreani, U. Bafile, F. Barocchi, F. Carsughi, A. Paciaroni Secretary SISN Francesco Aliotta Consiglio Nazionale delle Ricerche Istituto per i Processi Chimico-Fisici Via La Farina 237, 98123 Messina Fax: 090 2939 902 Tel: 090 2939 528 (*522, *183, *693) e-mail: Francesco Aliotta aliotta@adam1.its.me.cnr.it L’organizzazione del congresso SISN è stata curata da Roberta Rossi presso l’INFM di Genova.

PROGRAMMA 26th June 8:30-9:00

Registration

9:00-9:15

Welcome

9:15-9:45

R. Felici

9:45-10:15

R. Rinaldi "Neutron scattering on archaeological

10:45-11:15 11:15-11:45

S. Siano "Neutron diffraction studies of ancient

A. Botti "SANS on archaeological artefacts: limits and perspectives"

11:45-12:15

M. Zoppi "The Italian station INES, applications to

artefacts" 10:15-10:45

Coffee Break

Cultural Heritage " 12:15-12:45

Instrumentation Projects (15 minutes each talk)

bronzes"

BRISP Spectrometer at ILL IN13 Spectrometer at ILL

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SCUOLE E CONVEGNI

12:45-14:30

Lunch

14:30-15:00

L. Bove

15:30-16:00

C. Mondelli "Inelastic neutron study of molecular nanomagnets"

"Collective dynamics of liquid gallium

15:00-15:30

at 315 K and 973K"

16:00-16:15

Coffee Break

A. Pietropaolo

16:15

Assemblea Soci

"A novel technique for neutron spectroscopy at the eV energies"

27th June 9:00-9:45

K. Ross

12:45-14:15

Lunch

"Neutron scattering from hydrides" 9:45-10:30

Instrumentation Projects

G. Zaccai "Dynamical-Functional relations in

14:15-14:30

proteins, membranes and cells investigated by inelastic neutron " 10:30-10:45

at ISIS 14 :30-15:00 A. De Francesco

A. Deriu

"Lysozyme picosecond dynamics during

"Biophysics at future high intensity

protein unfolding in non-aqueous

neutron sources: from model systems

environment"

towards complex macromolecular a assemblies" 10:45-11:15

Coffee Break

11:15-11:45

F. Natali

15:00-15:30

systems"

16:30-17:00

D. Colognesi

interaction in model systems"

"Phonon density of states from a

R. Cordone

crystal-analyzer inverse-geometry

"Structure-dynamics coupling in tehalose

spectrometer: molecular and ionic

coated MbCO: a comparison between

solids"

FTIR and neutron (IN16 and IN13) data" A. Orecchini "Effect of the environment on the picosecond protein dynamics"

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S. Imberti "Solvation of ion OH- in water"

"Neutron investigation of lipid-protein

12:15-12:45

F. Mariani "SANS investigations of biological

15:30-16:00

11:45-12:15

VESUVIO and e.VERDI Spectrometers

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SCUOLE E CONVEGNI

JOINT CONGRESS AIC-SILS Trieste, 21-25 July 2003

Scientific Committeee Lucio Randaccio Paola Spadon Adriana Zagari Nicola Lovergine Gilberto Artioli Simona Quartieri Gianluca Cascarano Riccardo Spagna Giuseppe Filippini Maddalena Pedio Massimo Altarelli Giorgio Paolucci Carlo Maria Bertoni Claudio Furlani Settimio Mobilio Gianni Stefani Vincenzo Lombardi Antonio Franciosi Paolo Perfetti Calogero Natoli

ITALIAN CRYSTALLOGRAPHIC ASSOCIATION (AIC) (XXXIII NATIONAL CONGRESS) ITALIAN SYNCHROTRON LIGHT SOCIETY (SILS) (XI NATIONAL CONGRESS)

The XI SILS National Congress is held as a Joint Congress together with the XXXIII National Congress of the Italian Crystallographic Association (AIC). The meeting is organized in common microsymposia between the two Societies and in indipendent sessions.

During the common microsymposia aspects of interest for both the Societies will be treated, therefore they will be dedicated mainly to the study of the structural properties of the matter. In particular one microsymposium will be dedicated to studies in Archeometry and another to spectroscopies applied to structural properties.

The independent session of the SILS “Studies with Synchrotron Radiation” will be dedicated to the presentation of the best results achieved with synchrotron radiation during the last years, mainly in fields not

Organizing Committee Gilberto Vlaic Ennio Zangrando Silvano Geremia Letizia Pierandrei Michela Bassanese Andrea Goldoni Ilde Weffort

covered by the microsimposia of the Joint Meeting.This session will be held on Wednesday 23rd July 2003 and forsees contributed oral talk (20 minutes) and a poster session.

Further Information on Congress: http://www.elettra.trieste.it/AICSILS/

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SCUOLE E CONVEGNI

PROGRAM

The congress program will consist of plenary lectures (60 min), invited (30 min) and contributed (20 min) talks.

It will be divided into the following seven microsymposia.

Tuesday July 22nd 1) Diffraction in Materials Science 2) Progress of Structural Biology Promoted by Synchrotron Sources Wednesday, July 23rd 3) Structural Crystallograpy 4) Experiments, Modelling and Theories on Crystal Growth Mechanisms at the Atomic- and Nano-scaleâ&#x20AC;?

5) Studies with Synchrotron Radiation These microsymposia will be held in parallel sessions.

Thursday, July 24th 6) Spectroscopic Methods for Structural Investigations Friday, July 25th 7) Archeometry

POSTERS Posters will be exposed during all the period of the Congress.

A formal poster session will be held on Wednesday 23 rd .

Best posters will be awarded during the social dinner, on Thurdsday 23 rd evening.a

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SCUOLE E CONVEGNI

VII SCUOLA NAZIONALE DI LUCE DI SINCROTRONE Santa Margherita di Pula (Cagliari), 15-26 Settembre 2003

La SILS (Società Italiana di Luce di Sincrotrone) organizza la VII I Direttori della Scuola Prof. Settimio MOBILIO Dip. di Fisica "E. Amaldi" Università di Roma Tre Via della Vasca Navale 84 00046 Roma Tel. 0655177097 Prof. Gilberto VLAIC Dip. di Scienze Chimiche Università di Trieste Via Giorgieri 1 - 34127 Trieste Tel. 0405583931 - Fax 0405583903 e Laboratori Nazionali di Frascati Via E. Fermi 40 00044 Frascati (Roma) Tel. 0694032288 - Fax 0694032304 E-mail: mobilio@lnf.infn.it Sincrotrone Trieste SCpA Settore Esperimenti S.S. 14 Km. 163.5 34012 Basovizza, Trieste Tel. 0403758030 - Fax 0403758565 E-mail: vlaic@elettra.trieste.it

Scuola Nazionale di Luce di Sincrotrone, Santa Margherita di Pula (Cagliari) 15 – 26 settembre 2003 Le lezioni copriranno in maniera approfondita le singole tematiche; non è comunque necessaria nessuna conoscenza preliminare della Luce di Sincrotrone e delle sue applicazioni. La lingua ufficiale sarà l'italiano, solo alcune lezioni saranno eccezionalmente tenute in lingua inglese.

SCOPI DELLA SCUOLA Come per le sei edizioni precedenti (1990, 1992, 1995, 1997, 1999 e 2001) la Scuola intende offrire a persone già operanti nel campo della Luce di Sincrotrone o interessate ad entrarvi una panoramica attuale delle caratteristiche e potenzialità dell'uso della stessa. Le possibilità di ricerca con L. S. saranno affrontate sia da un punto di vista teorico che sperimentale e viste nella loro connessione a varie discipline (chimica, fisica, biologia, scienze della terra) e a diversi tipi di materiali.

Iscrizioni Il numero di partecipanti alla Scuola é limitato a 50 persone. Le domande verranno accettate in ordine cronologico di arrivo ai Direttori della Scuola. La tassa di iscrizione é fissata in 260 euro.

Scadenze temporali 30-5-2003 Invio della domanda di iscrizione ai Direttori della Scuola 31-6-2003 Invio ai partecipanti da parte dei Direttori della Scuola del programma definitivo e della scheda di prenotazione alberghiera 30-7-2003 Pagamento Tassa di Iscrizione; prenotazione alberghiera Borse di Studio "Carla Cauletti" La SILS, per facilitare la frequenza della Scuola, mette a disposizione alcune borse di studio intitolate alla memoria di Carla Cauletti; le borse saranno assegnate da una apposita Commissione SILS dopo la chiusura delle iscrizioni. Chi intende richiedere un sostegno economico è pregato di inviare il proprio curriculum-vitae al Prof. Gilberto Vlaic. Il numero delle borse a disposizione e la loro entità non può essere al momento quantificato, vista la contingente situazione economica del finanziamento alla ricerca in Italia.

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PROGRAMMA La Scuola si articolerà in circa 70 ore di lezione, in cui verranno trattati i seguenti argomenti: - Produzione e proprietà della L. S. - ELETTRA e ESRF: descrizione delle facilities; attività italiana a ESRF - Interazione radiazione-materia - Assorbimento di raggi X (EXAFS e XANES) - Diffrazione di raggi X (cristallo singolo, polveri, scattering anomalo, MAD, DAFS) - Spettroscopie di fotoemissione da livelli di valenza e di core (solidi e gas); fotoemissione risolta in tempo e in spin - Scattering a basso angolo - Scattering anelastico - Onde stazionarie - Dicroismo magnetico e naturale - Tecniche di microscopia e microspettroscopia con L. S. - Le applicazioni delle singole spettroscopie a vari tipi di materiali, tra i quali: biomolecole; materiali magnetici; catalizzatori; superfici (proprietà elettroniche e strutturali).

Sessione Poster Ci sembra utile organizzare in modo del tutto informale una sessione poster riguardante i lavori che ciascuno svolge o intenderebbe svolgere utilizzando la L. S., in modo da favorire gli scambi di idee e la nascita di collaborazioni tra i partecipanti alla Scuola.

Sede della Scuola Sala congressi Hotel Flamingo, Santa Margherita di Pula (CA) S.S. 195, Km. 33.800.

Sistemazione alberghiera I partecipanti saranno alloggiati presso l'Hotel Flamingo o presso l'Hotel Mare e Pineta. I due alberghi sono in riva al mare, situati all'interno di un parco privato di pini marittimi e di eucaliptus e distano tra loro circa 5 minuti a piedi. Il complesso è dotato di piscina, spiaggia privata, minigolf e campi da tennis. La Direzione dell'Albergo ci ha riservato 15 camere al Flamingo e 30 camere al Mare e Pineta. I pasti saranno serviti presso il Flamingo.

Prezzi di pensione completa per persona in camera doppia con servizi (bevande escluse): Hotel Flamingo**** 69 euro/giorno (supplemento singola 11 euro/giorno) Hotel Mare e Pineta*** 57 euro/giorno (supplem. doppia uso singola 15 euro/giorno) Riduzione tripla/quadrupla 25% Le condizioni di miglior favore praticate ai partecipanti saranno valide anche nel fine settimana precedente e in quello successivo alla Scuola. Le prenotazioni alberghiere e le spese di soggiorno andranno regolate esclusivamente con la Direzione dell'Albergo. Carte di credito accettate: American Express.

Hotel Flamingo & Mare e Pineta Hotel SS 195 KM. 33.800 09010 S. Margherita di Pula (CA) Tel. 0709208361 - Fax 0709208359

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SCUOLE E CONVEGNI

Altre informazioni Il tempo in Sardegna a settembre é generalmente buono; le temperature medie oscillano tra i 18 e i 28 °C. Poiché si tratta di un periodo di alta stagione turistica é consigliabile (specie se si viaggia con auto al seguito) prenotare i viaggi con largo anticipo.

VII Scuola Nazionale di Luce di Sincrotrone Santa Margherita di Pula (Cagliari) 15 – 26 settembre 2003

SCHEDA DI ISCRIZIONE Da spedire via fax o e-mail al Prof. Mobilio o al Prof. Vlaic

Nome e cognome

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Qualifica

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Indirizzo

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Telefono E-Mail

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Fax .........................................................................................................................

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Eventuale richiesta motivata di finanziamento (*) .................................................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................................................. ..................................................................................................................................................................................................................................................................................

Prevedo di partecipare alla sezione poster con un lavoro dal titolo: .................................................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................................................. ..................................................................................................................................................................................................................................................................................

Verserò la somma di euro 260 quale tassa di iscrizione appena ricevuta conferma della mia ammissione da parte degli organizzatori (entro il 30 luglio 2003). Entro la stessa data provvederò a inviare la scheda di prenotazione alberghiera (che mi sarà fornita dalla Direzione della Scuola). (*) La SILS mette a disposizione alcune borse di studio intitolate alla memoria di Carla Cauletti.

Inviare curriculum vitae al Prof. Gilberto Vlaic.

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CALENDARIO

August 3-8, 2003

SAN DIEGO, CALIFORNIA

September 8-18, 2003

SPIE Symposium on Nanocrystal Optics 2003 URL: http://www.infm.it

August 4-7, 2003

Eighth Oxford Summer School on Neutron Scattering Contact: Chick Wilson e-mail: c.c.wilson@rl.ac.uk URL: http://www.isis.rl.ac.uk/conferences/osns2003

VENEZIA, ITALY

Polarised Neutrons and Synchrotron X-rays for Magnetism.

A satellite of the International Conference of Magnetism, Rome 2003.

URL: http://venice.infm.it URL: http://www.icm2003.mlib.cnr.it

September 14-18, 2003

ARGONNE, IL, USA

Fifth National School of Neutron and X-ray Scattering Contact: Ray Osborn or dean Haeffner e-mail: nxschool@dep.anl.gov URL: http://www.dep.anl.gov/nx

August 21-22, 2003

PRETORIA, SOUTH AFRICA

African Neutron Diffraction meeting Contact: Andrei Ventre or Chick Wilson e-mail: amventer@aec.co.za; c.c.wilson@rl.ac.uk URL: http://www.sacrs.org.za/andm.index.html

August 26-30, 2003

GRENOBLE, FRANCE

Highly Frustrated Magnetism 2003 Contact: H.Mutka e-mail: HFM2003@ill.fr URL: http://www.grenoble.cnrs.fr/hfm2003/

September 3-6, 2003

STARA LESNA, SLOVAKIA

SSPD ‘03: Structure Solution from Powder Diffraction Data

September 15-26, 2003S.M.DI PULA, CAGLIARI, ITALY VII Scuola Nazionale di Luce di Sincrotrone E-mail: mobilio@lnf.infn.it vlaic@elettra.trieste.it

September 22-25, 2003

TRIESTE, ITALY

DyProSo XXIX Conferente/Elettra (Dynamical Properties of Solids) Contact: Ilde Weffort (secretary) e-mail: ilde.weffort@elettra.trieste.it URL: http://www.elettra.trieste.it/dyproso

October 15-18, 2003

BADAJOZ, SPAIN

First International Meeting on Applied Physics (APHYS-2003)

MONTPELLIER, FRANCE

ECNS2003: 3rd European Conference on neutron Scattering URL: http://www.ldv.univ-montp2.fr:7082/~ecns2003/ September 8-9, 2003

SORRENTO, NAPOLI, ITALY

EUCAS 2003: 6th European Conference on Applied Superconductivity URL: http://www.infm.it

September 14-19, 2003 August 10-24, 2003

OXFORD, ENGLAND

MANCHESTER, U.K.

2nd International Conference MECA-SENS: Stress Evaluation by Neutron and Synchrotron Radiation URL: http://www.mecasens.org

October 20-21, 2003 LOS ALAMOS NEW MEXICO, USA Sixth LANSCE User Group Meeting Contact: lance_user@lanl.gov URL: http://lansce.lanl.gov/conferences/LUG6/index.htm

Nov 28 - Dec 2, 2005

SYDNEY, AUSTRALIA

2005 International Conference on Neutron Scattering More information to follow soon

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SCADENZE

Scadenze per richieste di tempo macchina presso alcuni laboratori di Neutroni

Scadenze per richieste di tempo macchina presso alcuni laboratori di Luce di Sincrotrone

BENSC

ALS

Le scadenze per il prossimo call for proposals sono il 15 settembre 2003 e il 15 marzo 2003

Le prossime scadenze sono il 15 marzo 2004 (cristallografia macromolecolare) e il 1 giugno 2004 (fisica)

ILL BESSY

La scadenza per il prossimo call for proposals è il 26 febbraio 2004

Le prossime scadenze sono il 4 agosto 2003 e il 15 febbraio 2004

ISIS DARESBURY

Le scadenze per il prossimo call for proposals sono il 16 ottobre 2003 e il 16 aprile 2004

Le prossime scadenze sono 31 ottobre 2003 e il 30 aprile 2004

LLB-ORPHEE-SACLAY La scadenza per il prossimo call for proposals è il 1 ottobre 2004 per informazioni: Secrétariat Scientifique du Laboratoire Léon Brillouin, TMR programme, Attn. Mme C. Abraham, Laboratoire Léon Brillouin, CEA/SACLAY, F-91191 Gif-sur-Yvette, France.

Tel: 33(0)169086038; Fax: 33(0)169088261 e-mail: abraham@bali.saclay.cea.fr http://www-llb.cea.fr

ELETTRA Le prossime scadenze sono e il 31 agosto 2003 e il 28 febbraio 2004

ESRF Le prossime scadenze sono il 1 settembre 2003 e il 1 marzo 2004

GILDA (quota italiana) Le prossime scadenze sono il 1 novembre 2003 e il 1 maggio 2004

SINQ Le scadenze per il prossimo call for proposals sono il 15 Maggio ed il 15 Novembre 2003 To be addressed to Scientific Coordination Office WHGA/147 Paul Scherrer Institute CH-5232 Villigen PSI, Switzerland Phone: +41 56 310 2087 Fax: +41 56 310 2939 e-mail: sinq@psi.ch

HASYLAB (nuovi progetti) Le prossime scadenze sono il 1 settembre 2003, il 1 dicembre 2003 e il 1 marzo 2004

LURE La prossima scadenza è il 30 ottobre 2004

MAX-LAB La scadenza è approssimativamente febbraio 2003

NSLS Le prossime scadenze sono il 30 settembre 2003, il 31 gennaio 2004 e il 31 maggio 2004

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FACILITIES

LUCE DI SINCROTRONE SYNCHROTRON SOURCES WWW SERVERS IN THE WORLD (http://www.esrf.fr/navigate/synchrotrons.html) ALS Advanced Light Source Berkeley Lab, 1 Cyclotron Rd, MS6R2100, Berkeley, CA 94720 tel: +1 510.486.7745 fax: +1 510.486.4773 http://www-als.lbl.gov/ Tipo: D Status: O

ANKA Forschungszentrum Karlsruhe Institut für Synchrotronstrahlung Hermann-von-Helmholtz-Platz 1 76344 Eggenstein-Leopoldshafen, Germany tel: +49 (0)7247 / 82-6071 fax: +49-(0)7247 / 82-6172 http://hikwww1.fzk.de/iss/

APS Advanced Photon Source Bldg 360, Argonne Nat. Lab. 9700 S. Cass Avenue, Argonne, Il 60439, USA tel:+1 708 252 5089 fax: +1 708 252 3222 http://epics.aps.anl.gov/welcome.html Tipo: D Status: C

ASTRID ISA, Univ. of Aarhus, Ny Munkegade, DK-8000 Aarhus, Denmark tel: +45 61 28899 fax: +45 61 20740 http://www.aau.dk/uk/nat/isa Tipo: PD Status: O

BESSY Berliner Elektronen-speicherring Gessell.für Synchrotron-strahlung mbH BESSY GmbH, Albert-Einstein-Str.15, 12489 Berlin, Germany, tel +49 (0)30 6392-2999 fax +49 (0)30 6392-2990 http://www.bessy.de Tipo: D Status: O

BSRL Beijing Synchrotron Radiation Lab. Inst. of High Energy Physics, 19 Yucuan Rd.PO Box 918, Beijing 100039, PR China tel: +86 1 8213344 fax: +86 1 8213374 http://solar.rtd.utk.edu/~china/ins/IHEP/bsrf/bsrf.html Tipo: PD Status: O

CAMD Center Advanced Microstructures & Devices Louisiana State University, Center for Advanced Microstructures & Devices, 6980 Jefferson Hwy., Baton Rouge, LA 70806 tel: (225) 578-8887 fax. (225) 578-6954 Fax http://www.camd.lsu.edu/ Tipo: D Status: O

CHESS Cornell High Energy Synchr. Radiation Source Wilson Lab., Cornell University Ithaca, NY 14853, USA tel: +1 607 255 7163 fax: +1 607 255 9001 http://www.tn.cornell.edu/ Tipo: PD Status: O

CLS Canadian Light Source, University of Saskatchewan, 101 Perimeter Road, Saskatoon, SK., Canada. S7N 0X4 http://www.cls.usask.ca/ Tipo:D status:C

DAFNE INFN Laboratori Nazionali di Frascati, P.O. Box 13, I-00044 Frascati (Rome), Italy tel: +39 6 9403 1 fax: +39 6 9403304 http://www.lnf.infn.it/ Tipo:P Status: C

DELTA Universität Dortmund,Emil Figge Str 74b, 44221 Dortmund, Germany tel: +49 231 7555383 fax: +49 231 7555398 http://prian.physik.uni-dortmund.de/ Tipo: P Status: C

DIAMOND Diamond Light Source Ltd, Rutherford Appleton Laboratory, Chilton, Oxon OX11 0QX http://www.diamond.ac.uk/ Tipo:D status:C

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FACILITIES

ELETTRA Sincrotrone Trieste, Padriciano 99, 34012 Trieste, Italy tel: +39 40 37581 fax: +39 40 226338 http://www.elettra.trieste.it Tipo: D Status: O

Kurchatov Kurchatov Inst. of Atomic Energy, SR Center, Kurchatov Square, Moscow 123182, Russia tel: +7 95 1964546 Tipo: D Status: O/C

ELSA Electron Stretcher and Accelerator Nußalle 12, D-5300 Bonn-1, Germany tel:+49 288 732796 fax: +49 288 737869 http://elsar1.physik.uni-bonn.de/elsahome.html Tipo: PD Status: O

LNLS Laboratorio Nacional Luz Sincrotron CP 6192, 13081 Campinas, SP Brazil tel.: (+55) 0xx19 3287.4520 fax: (+55) 0xx19 3287.4632 http://www.lnls.br/ Tipo: D Status: C

ESRF European Synchrotron Radiation Lab. BP 220, F-38043 Grenoble, France tel: +33 476 882000 fax: +33 476 882020 http://www.esrf.fr/ Tipo: D Status: O

LURE Bât 209-D, 91405 Orsay ,France tel: +33 1 64468014; fax: +33 1 64464148 http://www.lure.u-psud.fr Tipo: D Status: O

EUTERPE Cyclotron Lab.,Eindhoven Univ. of Technol, P.O.Box 513, 5600 MB Eindhoven, The Netherlands tel: +31 40 474048 fax: +31 40 438060 Tipo: PD Status: C

MAX-Lab Box 118, University of Lund, S-22100 Lund, Sweden tel: +46 46 109697 fax: +46 46 104710 http://www.maxlab.lu.se/ Tipo: D Status: O

HASYLAB Notkestrasse 85, D-2000, Hamburg 52, Germany tel: +49 40 89982304 fax: +49 40 89982787 http://www-hasylab.desy.de/ Tipo: D Status: O

NSLS National Synchrotron Light Source Bldg. 725, Brookhaven Nat. Lab., Upton, NY 11973, USA tel: +1 516 282 2297 fax: +1 516 282 4745 http://www.nsls.bnl.gov/ Tipo: D Status: O

INDUS Center for Advanced Technology, Rajendra Nagar, Indore 452012, India tel: +91 731 64626 http://www.ee.ualberta.ca/~naik/accind1.html Tipo: D Status: C

NSRL National Synchrotron Radiation Lab. USTC, Hefei, Anhui 230029, PR China tel +86-551-5132231,3602034 fax +86-551-5141078 http://www.nsrl.ustc.edu.cn/en/enhome.html Tipo: D Status: O

KEK Photon Factory Nat. Lab. for High Energy Physics, 1-1, Oho, Tsukuba-shi Ibaraki-ken, 305 Japan tel: +81 298 641171 fax: +81 298 642801 http://www.kek.jp/ Tipo: D Status: O

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Pohang Pohang Inst. for Science & Technol., P.O. Box 125 Pohang, Korea 790600 tel: +82 562 792696 fax: +82 562 794499 http://pal.postech.ac.kr/english.html Tipo: D Status: C

FACILITIES

Siberian SR Center Lavrentyev Ave 11, 630090 Novosibirsk, Russia tel: +7 383 2 356031 fax: +7 383 2 352163 http://ssrc.inp.nsk.su/english/load.pl?right=general.ht ml Tipo: D Status: O

SSRL Stanford SR Laboratory 2575 Sand Hill Road, Menlo Park, California, 94025, USA tel: +1 650-926-4000 fax: +1 650-926-3600 http://www-ssrl.slac.stanford.edu/welcome.html Tipo: D Status: O

SLS Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI http://sls.web.psi.ch/view.php/about/index.html Tipo: D Status: O SPring-8 2-28-8 Hon-komagome, Bunkyo-ku ,Tokyo 113, Japan tel: +81 03 9411140 fax: +81 03 9413169 http://www.spring8.or.jp/top.html Tipo: D Status: C

SRS Daresbury SR Source SERC, Daresbury Lab, Warrington WA4 4AD, U.K. tel: +44 925 603000 fax: +44 925 603174 E-mail: srs-ulo@dl.ac.uk http://www.dl.ac.uk/home.html Tipo: D Status: O

SOLEIL Centre Universitaire - B.P. 34 - 91898 Orsay Cedex http://www.soleil.u-psud.fr/ Tipo: D Status:C

SOR-RING Inst. Solid State Physics S.R. Lab, Univ. of Tokyo, 3-2-1 Midori-cho Tanashi-shi, Tokyo 188, Japan tel: +81 424614131 ext 346 fax: +81 424615401 Tipo: D Status: O

SURF III B119, NIST, Gaithersburg, MD 20859, USA tel: +1 301 9753726 fax: +1 301 8697628 http://physics.nist.gov/MajResFac/surf/surf.html Tipo: D Status: O

TERAS ElectroTechnical Lab. 1-1-4 Umezono, Tsukuba Ibaraki 305, Japan tel: 81 298 54 5541 fax: 81 298 55 6608 Tipo: D Status: O

UVSOR Inst. for Molecular ScienceMyodaiji, Okazaki 444, Japan tel: +81 564 526101 fax: +81 564 547079 Tipo: D Status: O

SRC Synchrotron Rad. Center Univ.of Wisconsin at Madison, 3731 Schneider DriveStoughton, WI 53589-3097 USA tel: +1 608 8737722 fax: +1 608 8737192 http://www.src.wisc.edu Tipo: D Status: O

SRRC SR Research Center 1, R&D Road VI, Hsinchu Science, Industrial Parc, Hsinchu 30077 Taiwan, Republic of China tel: +886 35 780281 fax: +886 35 781881 http://www.srrc.gov.tw/ Tipo: D Status: O

D = macchina dedicata

D = dedicated machine

PD = parzialmente dedicata

PD = partially dedicated

P = in parassitaggio

P = parassitic

O = macchina funzionante

O = operating machine

C = macchina in costruzione

C = machine under construction

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FACILITIES

NEUTRONI NEUTRON SCATTERING WWW SERVERS IN THE WORLD (http://www.isis.rl.ac.uk) FRG-1 Geesthacht (D) Type: Swimming Pool Cold Neutron Source.

Flux: 8.7 x 1013 n/cm2/s Address for application forms and informations: Reinhard Kampmann, Institute for Materials Science, Div. Wfn-Neutronscattering, GKSS, Research Centre, 21502 Geesthacht, Germany Tel: +49 (0)4152 87 1316/2503; Fax: +49 (0)4152 87 1338 E-mail: reinhard.kampmann@gkss.de http://www.gkss.de

Atominstitut Vienna (A) Facility: TRIGA MARK II Type: Reactor. Thermal power 250 kW. Flux: 1.0 x 1013 n/cm2/s (Thermal); 1.7 x 1013 n/cm2/s (Fast) Address for information: 1020 Wien, Stadionallee 2 Prof. H. Rauch Tel: +43 1 58801 14111; Fax: +43 1 58801 14199 E-mail: boeck@ati.ac.at http://www.ati.ac.at Wap: wap.ati.ac.at

HMI Berlin BER-II (D) Facility: BER II, BENSC Type: Swimming Pool Reactor. Flux: 2 x 1014 n/cm2/s Address for application forms: Dr. Rainer Michaelsen, BENSC, Scientific Secretary, Hahn-Meitner-Insitut, Glienicker Str 100, 14109 Berlin, Germany Tel: +49 30 8062 2304/3043; Fax: +49 30 8062 2523/2181 E-mail: michaelsen@hmi.de http://www.hmi.de/bensc

NRU Chalk River Laboratories The peak thermal flux 3x1014 cm-2 sec-1 Neutron Program for Materials Research National Research Council Canada Building 459, Station 18 Chalk River Laboratories Chalk River, Ontario Canada K0J 1J0 Phone: 1 - (888) 243-2634 (toll free) Phone: 1 - (613) 584-8811 ext. 3973 Fax: 1- (613) 584-4040 http://neutron.nrc-cnrc.gc.ca/home.html

IBR2 Fast Pulsed Reactor Dubna (RU) Type: Pulsed Reactor.

Flux: 3 x 1016 (thermal n in core) Address for application forms: Dr. Vadim Sikolenko, Frank Laboratory of Neutron Physics Joint Institute for Nuclear Research 141980 Dubna, Moscow Region, Russia.

Tel: +7 09621 65096; Fax: +7 09621 65882 E-mail: sikolen@nf.jinr.dubna.su http://nfdfn.jinr.ru/flnph/ibr2.html

Budapest Neutron Centre BRR (H) Type: Reactor. Flux: 2.0 x 1014 n/cm2/s Address for application forms: Dr. Borbely Sándor, KFKI Building 10, 1525 Budapest, Pf 49, Hungary E-mail: Borbely@power.szfki.kfki.hu http://www.iki.kfki.hu/nuclear

FRJ-2 Research Reactor in Jülich (D) Type: Dido reactor. Flux: 2 x 1014 n/cm2/s Prof. D. Richter, Forschungszentrums Jülich GmbH, Institut für Festkörperforschung, Postfach 19 13, 52425 Jülich, Germany Tel: +49 2461161 2499; Fax: +49 2461161 2610 E-mail: d.richter@kfa-juelich.de http://www.kfajuelich.de/iff/Institute/ins/Broschuere_NSE/

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ILL Grenoble (F) Type: 58MW High Flux Reactor.

Flux: 1.5 x 1015 n/cm2/s Scientific Coordinator Dr. G. Cicognani, ILL, BP 156, 38042 Grenoble Cedex 9, France Tel: +33 4 7620 7179; Fax: +33 4 76483906 E-mail: cico@ill.fr and sco@ill.fr http://www.ill.fr

FACILITIES

IPNS Intense Pulsed Neutron at Argonne (USA) for proposal submission by e-mail send to cpeters@anl.gov or mail/FAX to: IPNS Scientific Secretary, Building 360 Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439-4814, USA Phone: 630/252-7820, FAX: 630/252-7722 http://www.pns.anl.gov/

IRI Interfaculty Reactor Institute in Delft (NL) Type: 2MW light water swimming pool.

Flux: 1.5 x 1013 n/cm2/s Address for application forms: Dr. A.A. van Well, Interfacultair Reactor Institut, Delft University of Technology, Mekelweg 15, 2629 JB Delft, The Netherlands Tel: +31 15 2784738; Fax: +31 15 2786422 E-mail: vanWell@iri.tudelft.nl http://www.iri.tudelft.nl

ISIS Didcot (UK) Type: Pulsed Spallation Source.

Flux: 2.5 x 1016 n fast/s Address for application forms: ISIS Users Liaison Office, Building R3, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX Tel: +44 (0) 1235 445592; Fax: +44 (0) 1235 445103 E-mail: uls@isis.rl.ac.uk http://www.isis.rl.ac.uk

JAERI (J) Japan Atomic Energy Research Institute, Tokai-mura, Naka-gun, Ibaraki-ken 319-11, Japan.

Jun-ichi Suzuki (JAERI); Yuji Ito (ISSP, Univ. of Tokyo); Fax: +81 292 82 59227 telex: JAERIJ24596 http://www.ndc.tokai.jaeri.go.jp/

JEEP-II Kjeller (N) Type: D2O moderated 3.5% enriched UO2 fuel.

Flux: 2 x 1013 n/cm2/s Address for application forms: Institutt for Energiteknikk K.H. Bendiksen, Managing Director, Box 40, 2007 Kjeller, Norway Tel: +47 63 806000, 806275; Fax: +47 63 816356 E-mail: kjell.bendiksen@ife.no http://www.ife.no

LLB Orphée Saclay (F) Type: Reactor. Flux: 3.0 x 1014 n/cm2/s Laboratoire Léon Brillouin (CEA-CNRS) Submissio by email at the following address : experience@llb.saclay.cea.fr http://www-llb.cea.fr/index_e.html

NFL Studsvik (S) Type: 50 MW reactor. Flux: > 1014 n/cm2/s Address for application forms: Dr. A. Rennie, NFL Studsvik, S-611 82 Nyköping, Sweden Tel: +46 155 221000; Fax: +46 155 263070/263001 E-mail: user.admin@studsvik.uu.se http://www.studsvik.uu.se

NIST Research Reactor, Washington, USA National Institute of Standards and Technology-Gaithersburg, Maryland 20899 USA Center Office: J. Michael Rowe, 6210, Director NIST Center for Neutron Research mike.rowe@nist.gov http://www.ncnr.nist.gov/

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FACILITIES

NRI Rez (CZ) Type: 10 MW research reactor.

Address for informations: Zdenek Kriz, Scientif Secretary Nuclear Research Institute Rez plc, 250 68 Rez Czech Republic Tel: +420 2 20941177 / 66173428 Fax: +420 2 20941155 E-mail: krz@ujv.cz / brv@nri.cz http://www.nri.cz

PSI-SINQ Villigen (CH) Type: Steady spallation source.

Flux: 2.0 x 1014 n/cm2/s Contact address: Paul Scherrer Institut SINQ Scientific Coordination Office CH-5232 Villigen PSI Phone: +41 56 310 2087 Fax: +41 56 310 2939 E-mail: sinq@psi.ch http://sinq.web.psi.ch

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SPALLATION NEUTRON SOURCE, ORNL (USA) http://www.sns.gov/

TU Munich FRM, FRM-2 (D) Type: Compact 20 MW reactor.

Flux: 8 x 1014 n/cm2/s Address for information: Prof. Winfried Petry, FRM-II Lichtenbergstrasse 1, 85747 Garching Tel: 089 289 14701 Fax: 089 289 14666 E-mail: wpetry@frm2.tum.de http://www.frm2.tu-muenchen.de