UMN School of Physics and Astronomy magazine 2020

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Neutrinos at DUNE

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Multi-Messenger Astronomy

SCHOOL OF

Annual Magazine ISSUE 19 14

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Physics and Astronomy

Inside: Solar Explorers

With results from the Parker Solar Probe, and small satellites for solar research.

School Head

PAUL CROWELL

A letter from the Head of the School The School of Physics and Astronomy has faced some unprecedented challenges in the last eight months, as the COVID-19 pandemic forced us to transition to remote instruction in March and has also had a significant impact on our research activities. Our faculty, staff, and graduate students have risen to the task, however, and not only were we able to complete the spring semester successfully, but we began the fall with the benefit of innovations developed over the spring and summer. We have been able to offer all of our regular undergraduate and graduate classes, and, after adaptations for safety, research activities in the School have largely restarted. In a couple cases highlighted in this newsletter, resourceful faculty have initiated new efforts focused on either the pandemic itself or providing opportunities for students and the general public, who may have more time to participate in activities such as citizen science.

In spite of these challenges, the work of the School has gone on, and we have been lucky to do so with the benefit of four new faculty members: Michael Coughlin, Andrew Furmanski, Maxim Pospelov, and Nadja Strobbe, who are profiled in this issue along with Aleksey Cherman, who joined us a year previously. Michael is a member of the Minnesota Institute for Astrophysics, and Maxim has joined the William I. Fine Institute for Theoretical Physics. Nadja and Andrew are the newest members of our experimental high-energy physics group, and Alexey has joined our nuclear theory group. New programs are also underway, including the National Science Foundation Traineeship in multi-messenger astrophysics. As you will also read about Please send class notes, comments and mailing list changes to: Jenny Allan School of Physics and Astronomy University of Minnesota 116 Church St. S.E Minneapolis, MN 55455 spa-alumni@umn.edu Paul Crowell, Head, School of Physics & Astronomy Jenny Allan, Editor

in this issue, instruments such as the Parker Solar Probe have been completely unperturbed by the pandemic, and new data from it and other experiments are generating particular excitement in our Space Physics Group. I continue to be amazed by the research accomplishments of all of our faculty, staff, and students.

Three members of the faculty, Professors Yuichi Kubota and Larry Rudnick and Regents Professor Allen Goldman retired at the end of the academic year. We thank them for their collective 127 years of service to the School and University. Allen’s 55 years on the faculty also included 13 as Head of the School, and he mentored over 65 graduate students. Unfortunately, we also suffered the unexpected loss of Professor Misha Voloshin, who passed away in March. Misha, who held the Gloria Lubkin Chair in Theoretical Physics, was a pioneer in the theory of heavy quarks, and was widely admired by both theorists and experimentalists around the world. We will also miss Emeriti Hans Courant, Walter “Cork” Johnson, and Cecil J. “Jake” Waddington, who are also remembered in this issue.

This newsletter is, in effect, a double-issue, as the combination of the School’s leadership transition and the pandemic delayed publication. In the future, please look forward to a new format of shorter, quarterly updates that link directly to stories on the School’s new web page: cse.umn.edu/physics. Among other features, the web page includes Zoom links to the School’s colloquium and many of our seminars, in addition to updates on our research, teaching, and outreach activities. Please join us for any of our online events. Of course we are looking forward to the return of the face-to-face interactions that are so important to education and the advancement of physics and astronomy. I will be updating you in the months ahead as we meet the challenge of restoring normal activities. Your support in this effort is valued by all of us in the School. In the meantime, please stay well, and I look forward to seeing members and friends of the School in person again as soon as conditions permit.

SCHOOL NEWS New Traineeship focuses on intersection of astrophysics and data science Professor Vuk Mandic is the principal investigator of a National Science Foundation (NSF) Research Traineeship program designed to train graduate students in data science, in the context of the nascent field of multi-messenger astrophysics. The new training program will be conducted by an interdisciplinary group of faculty, cutting across two colleges and five programs and will provide a total of 30 annual stipends for graduate students, during 2020-2024, each in the amount of $34,000 plus tuition and fees.

In 2017, a merger of two neutron stars was simultaneously observed as a gravitational wave signal by the LIGO and Virgo detectors, and as a Gamma Ray Burst by Fermi and INTEGRAL satellites. The event was tracked through the electromagnetic spectrum by numerous terrestrial and space-borne detectors and telescopes. This event is regarded as the birth of multi-messenger astrophysics, where astrophysical events are observed by multiple messengers enabling previously impossible scientific inquiries. The 2017 event has demonstrated this science potential by enabling novel tests of gravity, measurements of

the expansion of the universe, probes of the state of matter in neutron stars, and understanding of the origin of the heaviest elements in the periodic table.

In the future, vast amounts of new data are expected from existing and upcoming gravitational wave detectors, telescopes, gamma ray detectors, and neutrino detectors.

The size, complexity, and diversity of the new datasets will be unlike anything seen before in astrophysics. The Traineeship program will teach processing and analysis by training graduate students in modern data science techniques. The Traineeship will use the nascent field of multi-messenger astrophysics as a training ground to prepare students for the challenges of the modern data-driven workforce in both industry and academia. The trainees will work in interdisciplinary trainee teams, mentored by interdisciplinary faculty mentoring teams. The best practices developed by this program will be made available to STEM graduate programs across the nation.

Faculty members involved are Dan Boley (Computer Science), Lucy Fortson (Physics), Jarvis Haupt (Electrical Engineering), Galin Jones (Statistics), Pat Kelly (MIfA), Vipin Kumar (Computer Science), Vuk Mandic (Physics), Claudia Scarlata (MIfA), and Xiaotong Shen (Statistics).

Puchner group makes breakthrough in understanding the way cells use fat

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A research team at the School has made a breakthrough in understanding the way cells use fats. This discovery will help scientists better understand this process, which is linked to a number of diseases including diabetes and obesity. Assistant Professor Elias Puchner’s group recently published a paper in Nature Communications describing a novel technique for super resolution microscopy that they used to study fasted living cells.

They discovered that cells when fasted will not absorb fatty acids. Fatty acids are then trapped in the cell membrane and are only used when nutrition is returned to the cell. Puchner says that he assigned two students, Santosh Adhikari, Joe Moscatelli, to perform what was considered a boring, routine control experiment. They were studying BODIPY, a type of dye which has about 100 variations and is used in traditional microscopy, typically with green laser light. The students were supposed to test the dye with red laser light just to show that there would be no background fluorescence that might affect their measurements. But the students found that if live cells were stained with the dye, and then exposed to red laser light, they gave off a brief but very bright signal.

Further testing showed that this was a universal effect that happened with all kinds of BODIPY dye conjugates and cells, including medically relevant mammalian cells.

The group found by looking through the literature on BODIPY dyes, that some chemists had observed this effect in test tubes and provided an explanation for the phenomenon. Puchner says that no one had ever tried to exploit the phenomenon for super-resolution microscopy and that they quickly discovered they could study the behavior of fatty acids in a fasted cell at a much higher resolution than ever before. This led to the discovery that fatty acids are rejected by the cell, while it is fasting and not used until nutrition is restored. Puchner explains that the reason for this is the fact that fatty acid cells have both a hydrophobic (repelling water) and hydrophilic (attracting water) nature. Too much fatty acid in a starved cell is like putting too much dish soap in a sink, Puchner says. “The cells will poison themselves. So they have a protective mechanism that keeps them in balance until nutrition is restored.”

Puchner’s group has teamed up with Professor Douglas Mashek at the University of Minnesota Medical School to further study the phenomenon.

The lead authors on the paper were Santosh Adhikari, Graduate Student at the University of Minnesota and Joe Moscatelli, an undergraduate at Middlebury College in Vermont. Other members of Puchner’s group who contributed to the paper were Elizabeth M. Smith and Chiranjib Banerjee, School of Physics and Astronomy, University of Minnesota.

SCHOOL NEWS

Physics Professor creating a smartphone device for COVID-19 testing Professor Jochen Mueller is part of a collaboration at the University of Minnesota that is building a device for smartphones that will help health care providers identify the COVID-19 virus, i.e., SARS-CoV-2. The collaboration is accelerating research during this unprecedented crisis directed at the development of a point-of-care diagnostic test for use by healthcare providers - particularly in resource poor locations - to rapidly identify the virus in under ten minutes.

Using funding from the UMN Medical School’s Rapid Response Grants Program, Mueller and Prof. Louis Mansky, Director of the Institute for Molecular Virology at the University of Minnesota now have a working prototype.

Mueller and Mansky are keeping the required supplies and reagents to a minimum, in order to help the mass production of test devices beyond the prototype. This is particularly important, as one of the critical limitations with current tests is related to supply chain shortages.

Sensitive and accurate testing that minimizes the likelihood of false positives and false negatives is essential for a test to meaningfully contribute to the urgent need for testing that will help allow for safely lifting stay-at-home restrictions and to identify those who may later become exposed to the virus.

Most smartphones have a built-in camera with an image sensor of high quality. By adding an external lens, the smartphone can be reconfigured to work as a microscope.

The prototype created by Prof. Mueller’s research team uses a 3-D printed bezel to attach an inexpensive lens from a webcam to the back of a smartphone. A diode laser is incorporated into the bezel for detecting the virus by fluorescence, as well as a color filter to help improve the signal-to-noise ratio.

One of the challenges facing Mueller and Mansky has been accurate and sensitive virus detection. Mueller says that proteins on the surface of the virus particle are good targets for rapid virus detection. The SARS-CoV-2 spike protein is critical for virus entry into cells, and many copies of this protein decorate the surface of the virus particle, which visually creates a crown (i.e., corona) on the surface of the virus that can be seen by transmission electron microscopy. The SARS-CoV-2 spike protein interacts with the angiotensin converting enzyme 2 receptor protein, which is located on the surface of many cell types in the body, including the oral and nasal mucosa, nasopharynx, and lung.

Mansky and his research team are validating a virus detection assay that targets the SARS-CoV-2 spike protein using a fluorescently-labeled probe. The fluorescent label serves as the optical readout for the presence of the virus by the smartphone camera. Postdoc Rayna Addabbo is continuing this validation process in Dr. Mueller’s lab by using non-infectious virus particles carrying the spike protein.

John Kohler, a Ph.D. student in Mueller’s group, is using state-of-the-art fluorescence microscopy to help validate the sensitivity of the smartphone-based imaging device.

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Zooniverse experiences quarantine surge Zooniverse is the world’s largest and most successful citizen science platform, with over 2 million people contributing to research worldwide. It uses the web to bring together ordinary people and researchers who need help classifying data. Since the Covid-19 quarantine period began, Zooniverse has experienced a huge uptick in use by the public, around five times the usual number of classifications. Professor and Associate Head of the School, Lucy Fortson says that all the increased activity on Zooniverse research problems means that they are getting completed more quickly than expected.

“It’s a good problem to have,” Fortson says. For example, University Researcher Patrick Wilcox and others completed Muon Hunter 2 --which helps astronomers find elusive muons disguised as gamma rays-- ahead of schedule and

has launched Muon Hunter 3 earlier than expected. “We’re seeing that happen across many of our 100-150 live projects.”

Fortson is one of the co-founders of the Zooniverse as a platform. The Zooniverse began in 2007 with a single experiment called Galaxy Zoo, which used citizen scientists to sort galaxy images. At the time, Professor Fortson was VP for Research at the Adler Planetarium and had convinced them to start a Citizen Science Division. She met Galaxy Zoo founder, Chris Lintott, and joined forces, with Lintott serving as the first Adler Director of Citizen Science. When Fortson came to Minnesota in 2010, she brought Zooniverse with her, joining the University with the Adler and the University of Oxford as Zooniverse leads.

Her work has made the University one of the most active organizations using the platform with over 30 projects, attracting 50,000 participants in Minnesota alone.

SCHOOL NEWS

Shklovskii awarded Buckley Prize Professor Boris Shklovskii of the School and the William I. Fine Theoretical Physics Institute was awarded the Oliver E. Buckley Prize in Condensed Matter Physics. The prize recognizes his “pioneering research in the physics of disordered materials and hopping conductivity.” Shklovskii’s collaborator Alexei L. Efros as well as the late Elihu Abrahams were also awarded the prize. They were presented with the prize at a recognition ceremony at the 2019 meeting of the American Physical Society.

Mandic receives Distinguished McKnight Professorship Professor Vuk Mandic has been selected as a 2019 Distinguished McKnight University Professor. The award recognizes Mandic’s research in the field of experimental cosmology and astrophysics. Mandic will receive a grant of $120,000 to be used over a five year period. He will also retain the title of Distinguished University Professor as long as he remains at the University and his name will appear with other recipients of the Professorship on the Scholar’s Walk. The award recognizes outstanding faculty who have recently achieved full professor status. Only a handful of Distinguished McKnight University Professors are selected each year.

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Scarlata receives Taylor Research Award Associate Professor Claudia Scarlata won the 2019 College of Science and Engineering George W. Taylor Distinguished Research Award. The award comes with $3,000 to be used in Scarlata’s research in astrophysics. The Distinguished Research Award recognizes younger faculty members who have shown outstanding ability in research. Scarlata used the money to support an undergraduate student during the summer.

Scarlata’s current research is related to the problem of how the radiation that is able to ionize hydrogen can escape from galaxies and reach the intergalactic medium.

The student worked with data from the Hubble Space Telescope.

Cattell named Distinguished CSE Professor Professor Cynthia Cattell has been named a College of Science and Engineering (CSE) Distinguished Professor. She joins E. Dan Dahlberg, Allen Goldman, Ken Heller, Roberta Humphreys and Marvin Marshak as the sixth member of the SPA faculty to receive the distinction The professorship honors exceptional faculty for their efforts in and contributions to teaching and scholarly research and for their genuine commitment to the College of Science and Engineering and its activities. CSE Distinguished Professors receive a one-time award of $15,000 to be used for professional development or research.

Fortson receives Nicholson Medal Professor and Associate Head of the School Lucy Fortson has been awarded the 2019 Nicholson Medal for Outreach by the American Physical Society “for extraordinary work in bringing the excitement and discovery of scientific research to the public through her leadership of the Zooniverse project.”

The Nicholson Medal recognizes the humanitarian aspect of physics and physicists created through public lectures and public media, teaching, research, or science related activities.

It includes a stipend of $2,000, the Nicholson medal, and a certificate.

Fortson and Skillman named APS Fellows Lucy Fortson, Professor and Associate Head of the School, has been named a Fellow of the American Physical Society. She was cited for her “groundbreaking innovations to public engagement in astrophysics research, and for the fundamental advancement of understanding active galactic nuclei through leadership in high energy gamma ray astronomy.”

Professor Evan Skillman was elected a 2018 Fellow of the American Physical Society. He was cited for his contributions to “observational constraints on the primordial helium abundance and significant contributions to understanding the chemical evolution of galaxies.”

Each year, no more than one half of one percent of the Society membership is recognized by their peers for election to the status of Fellow in the American Physical Society. This year, 163 Fellows were selected and recognized for their contributions to science. The addition of Fortson and Skillman to this group, brings the total number of APS Fellows in the current faculty of the School to 42.

SCHOOL NEWS

Kakalios receives AAPT Award Professor James Kakalios of the School of Physics and Astronomy will receive the Klopsteg Memorial Lecture Award from American Association of Physics Teachers (AAPT). The award “recognizes outstanding communication of the excitement of contemporary physics to the general public.”

Fortson receives Taylor Award Professor and Associate Head of the School Lucy Fortson received the 2020 George W. Taylor Award for Distinguished Service from the College of Science and Engineering. The Taylor awards recognize outstanding faculty in the College. The Award comes with $3,000 to be used for professional development in teaching or research.

Janssen receives Taylor Award Professor Michel Janssen of the School of Physics and Astronomy received the 2020 George W. Taylor Award for Distinguished Teaching from the College of Science and Engineering at the University of Minnesota. The Taylor awards recognize outstanding faculty in the College. The Award comes with $3,000 to be used for professional development in teaching or research.

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Kapusta receives Graduate Teaching Award Professor Joseph Kapusta has received the 2020 Award for Outstanding Contributions to Graduate and Professional Education.

Kapusta has mentored 19 Ph.D. graduates and 25 postdocs since joining the faculty at the University of Minnesota. They have gone on to distinguished careers in academia, with many of them obtaining tenure at prominent research universities, as well as industrial positions. Kapusta was cited with praise for his “advising style and unique strengths as a teacher-scholar, focusing on each mentee’s needs while ensuring that they receive outstanding technical training and connections.”

The award was created in 1998 to recognize a select group of faculty members for their outstanding contributions to graduate and/or professional education.

Hanany receives Morse Award Professor Shaul Hanany has received the 2020 Horace T. Morse-University of Minnesota Alumni Association Award for Outstanding Contributions to Undergraduate Education.

Hanany was cited for having “driven significant changes in the School’s undergraduate program, and he launched a new initiative that impacts students’ professional lives through more informed career choices. He is an innovator in the classroom and an education role-model among colleagues. Hanany has mentored tens of undergraduate students in research, works to increase underrepresented populations in the sciences, and he imparts the fun of physics to tens of thousands of spectators every year through his leadership of the School’s Physics Force outreach program.” The Morse-Alumni Association teaching award was created in 1965 to honor a select group of teachers who reflect the University’s emphasis on the importance of high quality undergraduate education.

Glesener and Pribiag receive McKnight Awards Assistant Professor Lindsay Glesener was named as a 2020-2022 McKnight Land-Grant Professor.

The Professorship comes with $50,000 over two years to develop research. Glesener is a space physicist whose research focuses on high energy particles from the sun. Her group uses the novel method of focusing X-ray telescopes to investigate energy release and particle acceleration in solar flares. This involves building new telescopes and flying them into space to unravel the high energy mysteries of the Sun. Vlad Pribiag was named a 2019-2021 McKnight Land-Grant Professor. The program is designed to advance the careers of new assistant professors at a crucial point in their professional lives. Pribiag’s research is in novel low-dimensional quantum materials and devices for information processing. This research investigates new materials, aimed at transcending the limitations of traditional computers.

Gherghetta receives Simons Fellowship Professor Tony Gherghetta received the 2019 Simons Fellowship. The Simons Fellows program extends academic leaves from one term to a full year, enabling recipients to focus solely on research for the long periods often necessary for significant advances. Gherghetta is a theoretical physicist specializing in physics beyond the standard model.

SCHOOL NEWS

AGU Honors Pepin’s Distinguished Career in Planetary Science

Photo by Olivia Hultgren

Associate and eventually took over the lab when Signer returned to Switzerland a few years later.

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Professor Emeritus Robert Pepin will receive the 2020 Fred Whipple Award from the American Geophysical Union (AGU). The award recognizes “significant contributions to the field of planetary science from a midcareer or senior scientist.”

“I am definitely in the senior scientist category,” Pepin jokes. Such remarks are completely characteristic of Pepin and tend to bely his remarkably distinguished career in the field. His lab focused on analysis of “pretty much any extra-terrestrial material I could get my hands on” making many key measurements elucidating the noble gas compositions of the moon, Mars, interplanetary dust particles (IDPs), and comets. He began as a consultant to the Apollo missions in the sixties and seventies and remains active in that capacity with the Mars Curiosity rover. A detailed recent paper, published in 2019, was the culmination of the laboratory’s measurements over several years, carried out by Russ Palma and Dennis Schlutter, of dust grains returned to Earth in 2006 by the Stardust mission after it visited comet Wild and collected samples from the coma (the envelope of vaporized water and dust around a comet. Reflections of sunlight from the coma are typically what allow comets to be most readily observed by astronomers).

Pepin received his Ph.D. in 1964 from Berkeley under John Reynolds, measuring noble gases in meteorites.

Reynolds’ lab pioneered using mass spectroscopy to measure the distribution of these extraterrestrial gases that had never been seen before. When he graduated, Reynolds contacted University of Minnesota Professor Al Nier--sometimes referred to as the Father of Mass Spectroscopy--to see if Nier had a place for Pepin. Nier didn’t have any openings in his lab, but found a place for him working with Peter Signer, from Switzerland, who had come to Minnesota to do mass spectroscopy on meteorites. Pepin joined Signer’s lab as a Research

Pepin continued running Signer’s lab in Tate Laboratory until planning for lunar sample returns by the Apollo Missions became front and center in the mid 1960s. NASA put a lot of money into lab instrumentation and Minnesota got a cash infusion to create a special lab to analyze mission samples.

“We moved everything out of the sub-basement of Tate [Lab] to Shepherd Lab (then called the Space Science Center) to analyze lunar samples.” Pepin notes that their joint proposal to NASA to build the mass spectrometry equipment and analyze the samples was the one time that he and Professor Nier had their names on the same paper. His years as a NASA consultant and memberships on various committees resulted in some unique experiences such as attending a pre-flight geology field trip, and briefing astronauts how to collect and store lunar samples. He also sat as a science advisor in Mission Control for Apollo flights 14-17. He recollects that in four missions he was only called upon only once to make a sampling decision in real time. “On Apollo 15, the drill core got stuck, and the astronauts were having difficulty in pulling it out of the lunar soil. I was asked if we should keep them there or abandon it and go on with their traverse. I advised them to continue with their efforts to retrieve it, and they did eventually get it out. I took some flak from the crew for that decision, but when the core turned out to yield important insights into how and when the strata of lunar soil vs. depth were emplaced, everyone mellowed out.”

After Apollo ended in 1972, Pepin took an extended leave of absence from the University to serve as director of the Lunar Science Institute, a branch of the University’s Space Research Association funded by many universities (including Minnesota), located outside the gates of NASA in Houston. He returned to Minnesota in 1975, just in time to participate in interpretations of Viking data on the composition of the Martian atmosphere.

Later, the recognition that some of the meteorites in curatorial collections actually come from Mars, widened this atmospheric study enormously, first through the discovery by Don Bogard and colleagues at NASA/Houston that gases in one of these meteorites strongly resembled the Viking atmospheric measurements, and then by work at Minnesota that showed that nitrogen composition tallied with the unique Mars atmospheric N2 composition, and moreover showed that gases from the Martian atmosphere were implanted into these meteorites by severe shock, probably associated with the impact that ejected them from the planet. This established an acceptance of their Martian origin, a finding conclusively verified years later by Conrad, Pepin and others in their report of an almost identical xenon composition obtained by direct Continued on Page 16

ANDREW FURMANSKI, Assistant Professor

Faculty Profile

ANDREW FURMANSKI

NEUTRINOS AT DUNE

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Andrew Furmanski joined the faculty in Spring 2020. He comes to Minnesota to work on neutrino oscillation experiments.

“For the past 20 years or so, this field has been dominated by experiments in Japan and the US,” Furmanski says. “Two of the most successful and famous US-based experiments were both hosted jointly between Fermilab and UMN. They used big detectors in northern Minnesota to detect neutrinos sent from Fermilab. These experiments really put Minnesota on the map of neutrino physics so the group has some serious pedigree in this field!”

Prior to Minnesota, Furmanski worked on MicroBooNE at Fermilab. MicroBooNE is a short baseline neutrino experiment (Minnesota experiments DUNE, NOvA, and MINOS are “long baseline” neutrino oscillation experiments, looking for neutrinos changing type across hundreds, even thousands of miles.) There is some evidence that the same types of neutrinos might also change type across much shorter baselines. It turns out one explanation for this is additional neutrinos, which are known as sterile neutrinos, because they don’t interact with anything. The only evidence for them is these oscillations. However, Furmanski says “there is quite a lot of tension with other experiments that have looked for, and failed to find these oscillations.”

MiniBooNE was a short baseline experiment that ran at Fermilab. It saw a signature, but there was some question that it could be caused by something else. MicroBooNE is a new detector, smaller than MiniBooNE, using the same beam. MicroBooNE uses liquid argon, the same technology that the Deep Underground Neutrino Experiment (DUNE) will use. The DUNE far detector will be located the Homestake Gold Mine in Lead, South

Dakota and it will measure neutrinos beamed from Fermilab outside of Chicago, IL. Liquid argon gives better differentiation between photons and electron neutrinos.

Furmanski will be involved in the DUNE Near Detector, which is located at Fermilab. “What we’ve learned at MicroBooNE has already told us a lot about how we can build DUNE better. And how we can make better use of the data.” There are a few things that MicroBooNE showed for the first time. For example, in order to remove impurities from liquid argon, most people would suck all the air out of their cryostat before filling it with liquid argon, but when you build something the size of DUNE that’s impossible. “So we showed that you don’t have to do that. We slowly injected cold argon gas in the bottom of the detector, which pushes the air out of the top like a piston, because argon gas is heavier than air.” MicroBooNE showed that really high argon purity could be achieved and maintained it for 4 years (and counting). “Argon is just a gas in the air, so if you cool down air then you can extract pure argon as a cold liquid. Even MicroBooNE needs 180 tons of it, which means for DUNE, they will be cooling down something the volume of the empire state building. “We need to worry about the fact that we will be using up a large fraction of the total production capacity of liquid argon in the US. That will actually mean the price will go up while we’re filling DUNE.” DUNE is being built to further understand neutrino oscillations and their role in such key physics questions as the origin of the universe and the formation of black holes.

It will also search for signs of proton decay or the theory that protons decay into lighter, sub-atomic particles, which was hypothesized more than fifty years ago.

ProtoDUNE: the 600 ton prototype for the 40,000 ton DUNE detector.

Faculty Profile

MICHAEL COUGHLIN, Assistant Professor

MICHAEL COUGHLIN

MULTI-MESSENGER ASTRONOMY

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Michael Coughlin is a new faculty member in astrophysics.

Coughlin is originally from the Twin Cities and became involved in the Laser Interferometer Gravitationalwave Observatory (LIGO) Scientific Collaboration while a student at Carleton College in Northfield, working with Professor Vuk Mandic. After doing his Masters at Cambridge in the UK and his Ph.D. at Harvard, he spent time at the California Institute of Technology as a post-doc before returning home to Minnesota.

He is still a part of LIGO, and gravitational waves play a large part in his many research interests. Coughlin’s research uses techniques in multi-messenger astrophysics.

The principal behind “multi-messenger” research is to coordinate observations of objects with multiple types of observation tools. These could be groundbased telescopes, space satellites and telescopes, or interferometers like LIGO. The benefit for this coordination is to discover as many aspects of the same phenomenon as possible.

While in graduate school, Coughlin started working in optical instrumentation on a forthcoming telescope, the Vera C. Rubin Observatory in Chile. “Part of my Ph.D was working on the camera and calibration for that telescope. I got interested in combining the work I was doing in LIGO with the optical instrumentation.” Coughlin, at that point, began looking for optical counterparts to gravitational waves, in other words using LIGO sources to find the same object or phenomenon with a telescope. For example, the merger of either two neutron stars or a neutron star and a black hole, which can be detected by LIGO, produces an optical signature known as a kilonova. Using LIGO data combined with optical instruments to pinpoint a kilonova

could help astronomers gain better understanding not only of the phenomenon, but of how heavy elements are produced in the Universe. A kilonova creates a hot dense environment, and cosmologists believe this type of environment was what created heavy elements, such as gold. “With gravitational waves, I’d never be able to tell you what elements formed in the aftermath. In order to say what came afterwards, you really want to be looking at these other wavelengths, probing a different part of the process.”

The whole point of using all these different tools to look at the same object is to get a more complete understanding of them than you could with just one. It’s a fairly simple concept, but it requires the ability to cross different fields of science. “I didn’t start out doing astronomy, I started out as a physicist working on LIGO. Now I’m working on a camera for a telescope. It’s interesting to see if you can bring the instruments together and also the people in the community. Someone who studies the kilonova in detail will think of the problem very differently than LIGO people would. It’s a challenge to bring those communities together.” Coughlin is also working with a collaborator on a book about Multi Messenger Astronomy. “It’s really inspiring, to talk to the towering giants in their field.”

Coughlin is teaching a new class this spring in multi messenger astronomy. He is co-teaching with Michael Steinbach in Computer Science. The class will address one of the biggest challenges in multi-messenger astronomy: dealing with huge data sets that come with combining multiple areas of astronomy.

Coughlin is also in the process of building a low resolution spectrograph, the SED Machine #2, to assist with multimessenger projects. “We’re studying binary white dwarfs, and we’re building the spectrograph to look at them as well as transient sources. When we do LIGO follow-up, we find all sorts of things we weren’t looking for..” The low resolution spectrograph will help them characterize the objects quickly, sorting out the things they don’t care about and studying those in detail that they do.

NADJA STROBBE, Assistant Professor

Faculty Profile

NADJA STROBBE

SEARCHING FOR SUPERSYMMETRY Nadja Strobbe is a new faculty member in experimental high energy physics at the School. She is a member of the Compact Muon Solenoid (CMS) Experiment at the Large Hadron Collider (LHC) in Switzerland. Originally from Belgium, Strobbe comes to Minnesota via Fermilab where she was a Research Associate.

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The main focus of her research is looking for phenomena of supersymmetry using new avenues that haven’t been tried yet. Supersymmetry is a theoretical extension of the Standard Model that aims to fill some of its gaps. It predicts a partner particle for each particle in the Standard Model.

These new particles would solve a major problem with the Standard Model – fixing the mass of the Higgs boson. To date, there has been no evidence for supersymmetry, though experiments at the LHC have ruled out some of the simplest models.

well as provide more accurate detection and faster signal collection.

After the phase two upgrade, Strobbe will change her approach to doing really precise standard model measurements to look for Supersymmetry. “In the next 10-15 years we will have very precise measurements and we’ll be able to tell if there is something there. With these very precise searches, you could see the effect on other observable particles. For example, looking at the way the Higgs Boson decays, there may be places where it differs from the expected path. To do that you need a lot of data. By the end of the high luminosity period (2025-2035) we should have 20 times more data.”

Strobbe is excited to be back in an academic environment for the first time since she finished her Ph.D in 2015. “It’s nice in the HEP group. There are people working on neutrino physics and dark matter. I’m excited to be in an environment with more interaction with other areas in particle physics. At Fermilab everyone is separated into their own floor, and their own projects. You interact with the people in your project, which is a vibrant community, but the people working on neutrinos have their own coffee machine so we don’t see them often. Having a smaller group of people here will make it easier to interact with people outside of CMS.” Strobbe is also looking for graduate students to join her research.

The LHC is a 17-mile-round ring of magnets that accelerates two beams of protons in opposite directions, each to 99.999999999% the speed of light, and forces them to collide at the centers of CMS and the LHC’s other experiments.

Strobbe’s past work on the LHC included testing components for the multi-year phase one upgrade, which will improve the detector as well as replacing parts that have aged due to exposure to radiation during the accelerator’s operation from 2015-2018. After shutting down for the upgrades, the accelerator is scheduled to run again from 2021-2024. Strobbe is currently working on another upgrade, phase two, which will begin in 2025. “The accelerator will have upgraded power; our detectors need to be upgraded to match.”

Strobbe joined the CMS group at Minnesota, working with Professor Jeremy Mans on the endcap calorimeter. The existing calorimeter, which measures the energy of particle collisions, will not be able to withstand the radiation of an upgraded accelerator. The new sensors will be silicon based and should be able to withstand the increased radiation, as

CMS Image showing an event that is a possible candidate for new physics.

ALEKSEY CHERMAN, Assistant Professor

Faculty Profile

ALEKSEY CHERMAN

NEW TOOLS SHED LIGHT ON AN OLD PROBLEM

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Aleksey Cherman is a faculty member in the nuclear theory group. He may be relatively new to the faculty, but he is not new to the School.

Cherman worked as a postdoctoral researcher with the Fine Theoretical Physics Institute from 2012-2015 before returning to Minnesota in Fall of 2018.

Cherman has set out to study one of the most important questions in nuclear theory in the last thirty years. At the core of matter are protons and neutrons, and inside those are particles called quarks. “If you look at stars, old stars, neutron stars, you can find matter in extreme conditions.

It’s very very dense. It’s better to describe it not in turns of atoms, because they get smashed, but to describe it in terms of protons and neutrons.” Densities are so great that physicists don’t know whether to describe matter as protons and neutrons; or quarks. If you squeeze matter enough, the protons and neutrons look like quarks. “We don’t know if neutron stars are dense enough to do this.

As you squeeze does this soup change in a smooth way or are there jumps?” Cherman asks. The jumps would be phase transitions, similar in concept to those studied by condensed matter physicists. For thirty years physicists have wondered about this relatively sharp change in the phase of matter at the core of neutron stars.

After all this time, it looked like there was no phase transition. “There was no reason to require a phase transition so people thought there wasn’t one.” Most efforts have focused on using quantum field theory-- a tool for describing quarks and other particles. Cherman’s work has been to attack the problem using powerful new tools developed by theoretical condensed matter physicists and high energy particle theorists to set out to look for a phase transition in dense matter. “Now we are seeing that there is good evidence that there could be a phase transition. If neutron stars are dense enough it could be relevant to the physics of neutron stars.”

Before he could do this, the tools needed to be modified to work on this problem. Cherman’s recent efforts focus on making sure that his tools are calibrated correctly. “Any time you propose a new theoretical tool, you really have to find examples to show that this tool isn’t misleading you.”

In the past, Cherman has developed techniques applying quantum field theory to questions in condensed matter, high energy and nuclear physics. And Cherman sees this exchange of tools as being a two-way street. “One of the things I’d like to do is to take some of the ideas that we developed in studying dense nuclear material, that were gleaned from condensed matter physics, and look at condensed matter problems and see if we could learn something new with these modified tools.”

Cherman’s work has benefitted by returning to Minnesota. “One of my favorite things about the department is that there are very strong nuclear, condensed matter and particle groups. I get to interact with everyone and benefit from this broad strength across all these groups because my interests cross these boundaries.

Diagram shows that in super-dense superfluid quark matter, superfluid vortices trap color magnetic fields, leading to an Aharonov-Bohm effect for particles moving through the superfluid.

MAXIM POSPELOV, Professor

Faculty Profile

MAXIM POSPELOV

OUTSTANDING PUZZLES Maxim Pospelov is a new faculty member in high energy physics at the Fine Theoretical Physics Institute. “I was a post doc at FTPI twenty years ago and now find myself replacing, if such a thing were possible, my mentor, Arkady Vainshtein.

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Pospelov says that in the intervening years he’s learned to be broad. “Obviously the discovery of the Higgs was a big thing, but now we’re entering this stage where it’s not entirely clear where the new break will come. We have a few outstanding puzzles, Dark Matter, Dark Energy, and outstanding irregularities in particle physics.” His interests have expanded to include cosmology, CP violation, flavor physics, and Dark Matter.

“Back 20 years ago, when I was a postdoc, it would be ok for a young theorist to write a paper to propose a new model and make a prediction.” It was said that theory was twenty years ahead of experiment in the field. “Now people say ‘so what’ you have a new model, but what are we going to do to test this? Whatever theoretical idea you have needs to have experimental verification.” In the last 10 years, theorists have been dreaming up new experimental ideas to test theoretical models. Pospelov has collaborated with experiments attempting to branch out and look for the signature of particle physics that the LHC hasn’t yet found.

Pospelov is interested in the strong CP problem (A long-standing physics problem caused by the fact that a predicted violation in Charge-Parity or CP symmetry could occur in strong interactions, but has never been observed to do so) and the problem of flavor (above certain energies, a particle’s flavor is behaves differently than in the Standard Model of particle physics.)

One area of interest is in developing new ways to look for Dark Matter, by looking for the signatures of Dark Matter’s interactions, so-called Dark Radiation, in experiments designed to study very different interactions . One of the ways this signature could be detected is in neutrino detectors, such as the Deep Underground Neutrino Experiment (DUNE), in which many members of the high energy experimental physics group at Minnesota are involved. Pospelov hopes that theorists will be able to propose experiments with DUNE to look at physics beyond the Standard Model.

He is also interested in more conventional uses for DUNE, which is to understand the anomalies in neutrino physics.

To that end, he has a post doc--Dr. Matheus Hostert, who came to Minnesota last year--working on anomalies in theoretical neutrino physics. “You make a prediction and if the measurement varies by 1% that’s not an anomaly but if it varies by a lot, there are statistical ways to characterize it.” In neutrino physics there are several observations that don’t fit the theory. They could be new physics or errors in experiment. Pospelov says it’s fairly common for experimentalists to underestimate the amount of error in an experiment. That can lead to doubt about the quality of the experiment, but as the experiment continues, and data piles up, that doubt goes away.

“Theorists are good at providing some alternative explanations. It may well be that some are missing processes that weren’t accounted for and those missing processes could be new particles that we didn’t know exist.

There are some that could be very subtle effects with known particles that could be the reason. It’s everyone’s job to think how it can be resolved, it’s not necessarily theory or experiment.”

CHARITABLE GIVING TO THE SCHOOL Why We Give: 2020 Scholarship Winners Thank you to you, our alumni, faculty and friends who contribute to the School of Physics and Astronomy. I hope you and yours are staying safe and doing well.

During this unprecedented time, your support is more important than ever. Please consider a gift to help keep our students’ higher education goals within reach. We have many scholarships and fellowships listed on the website: cse.umn.edu/physics/ giving-school-physics-and-astronomy. You’ll notice the most recent scholarship established in honor of Professor Marvin Marshak and his wife Anita Kolman. Additionally, the Physics General Fund provides flexibility to fund new ideas and address needs within the department.

Shannon Weiher

Gifts of all sizes make a tremendous difference to our program. The recently passed CARES Act provides several opportunities to make a tax-advantaged gift that creates lasting support. More information is available at give.umn.edu/stories/cares-act. Donor Advised Funds, gifts that provide income, and non-cash assets like real estate or tangible personal property can also maximize your gift intentions.

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Please feel welcome to contact me with your questions regarding charitable giving opportunities at (612) 624-5534 and seweiher@umn.edu.

Shannon Weiher External Relations cse.umn.edu/college/give-cse

Alfred O. C. Nier Scholarship Amanda Gatto Lamas Allen M. Goldman Fellowship Dmitry Chichinadze Anatoly Larkin Fellowship Sarunas Nedzinskas Verner Aneesur Rahman Award Andrew Miller, Sharan Banagiri Anita Sue Kolman and Marvin L. Marshak Scholarship Alec Nilson, Spencer Swanson Basford Family Scholarship Joseph Dill, Ben Leiran, Jack Zwettler Craig R. Holt Scholarship Kiet Pham Edmond B. Franklin Scholarship Jesse Donahue, Sylvia Griffitt, Thomas Richardson, Rory Spanier, Tien (Anthony) Vo, Chenyu (Kole) Yu Hagstrum Award Tobey Haluptzok Harry and Viola St. Cyr Scholarship Sauviz Alaei Hazel V. Swanson Scholarship Daniel Ubanski, Hannah Bjorklund, Ramona White Hoff Lu Fellowship Theodore Jacobson J. Morris Blair Scholarship Jason Bassil, Haoyang Li Karlis Kaufmanis Lectureship Samuel Corey, Kekoa Lasko, Mason Huberty Laverne & Ted Jones Astrophysics Scholarship Arunn Suntharalingam, Anne Duerr, Ian Morrissey Outstanding TA Award Bryan Crossman, Wen-Han Kao (Kao), Sarunas Nedzinskas Verner, Swetlana Swarup, Tien (Anthony) Vo Oswald Scholarship in Physics Zi Wang Robert E. Greiling Jr. Fellowship Yaren Aksel, Kivanc Bugan, Onuray Sancar Robert O. Pepin Fellowship Santosh Adhikari

CLASS NOTES 1962 Larry Finger (B.S. Physics) I have fond memories of my years at Minnesota. In particular, I remember the freshman lab where they taught us how to propagate errors before we had calculus. Although the TA’s did not call it differential calculus, that was what we were doing. Physics was so interesting that I transferred from Electrical Engineering to Physics at the end of my first year. The upper-class lab where we repeated famous experiments was also memorable. For the Cavendish experiment, we were given keys to the building so that our results would not be disturbed by the elevator or other activities. The MXP courses described in Issue 18 are intriguing. Although I left formal physics after 4 years, I only strayed into crystallography as taught in the Geology Department. My physics background was invaluable there and in the research career that followed.

2003 Ricky Egeland (B.S. Physics) Roger Rusack (Advisor) I have accepted a Project Scientist position at the National Center for Atmospheric Research High Altitude Observatory. I am currently working on Hinode spectropolarimeter data analyses and operations, spectropolarimetric inversions for the upcoming 4-meter DKIST solar telescope, and applications of machine learning to solar spectropolarimetry.

2011 Mari Núñez Valdez (Ph. D Physics) In 2013 I went to do postdoctoral work at the ETH in Zürich, CH. In 2015 I became a research fellow at the Moscow Inst. of Physics and Technology in Russia. In 2017 I moved to Germany after winning W2 funding for excellent female scientists from the Helmholtz Association. Now I work for the Helmoltz-Zentrum Potsdam (GFZ) and I am a W2-Professor for “atomistic modeling of (geo)materials” at the Goethe University Frankfurt am Main. I always remember the UMN and everything that I learned from the physics department during my grad school years and the TA experiences I had.

I particularly enjoyed the lectures from Professors Shklovskii, Kamenev, Peloso, Vainshtein and Voloshin, and TAing for Professors Poling, Heller, Kakalios and Courant.

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2014

Sean Bartz (Ph.D. Physics) joined Indiana State University as an Assistant Professor of physics in 2018.

He is working with undergraduate students on projects in nuclear theory and high-power rocketry.

2018 Sarah Stangl (B.S. Physics and Astrophysics) Terry Jones, (Advisor) I am worked at LANL as a graduate research assistant in the summer, and am working on my PhD during the school year

In Memoriam Charles B. Archambeau (B.S. Physics 1955) 1933-2020, 87, was a professor at the California Institute of Technology (1966-1974) and was a professor and member of the scientific research staff at the University of Colorado (1974-1998). He was a scientific consultant to numerous companies. He was a research fellow at the Cooperative Institute for Research in Environmental Sciences (CIRES) and a visiting fellow at the Center for Seismic Studies. In 1986 he designed an experiment which used seismography to confirm that the Soviets were testing nuclear weapons underground. He was the recipient of a MacArthur Genius Grant in 1988. Since 1995, he was president and chief research scientist of Technology Research Associates Corporation, a research company specializing in the area of passive seismic transmission and emission tomography.

Carlos P. Avery (Ph.D. 1967), 1938-1981, 81, former CIA physicist who spent his spare time researching and writing about the designer of notable Baltimore landmarks. Carlos was born in Hutchinson, Minnesota.

At the School he met his future wife, Sara Lynn Torvik.

Carlos joined the Central Intelligence Agency in Langley, Virginia. He spent his career at the agency in various roles, in the areas of Soviet science, technology, and strategic defense weapons, as well as Y2K and Iraq, marking 50 years of service in March of 2017. In the 1970s, he began studying railroad architecture in Baltimore and became an expert on local history and architecture.

Paul Aanond Knutson (B.S. Physics 2002, Ph.D. Physics 2011) 1939-2019, 80, of Minneapolis, MN died peacefully from complications from pneumonia on Feb. 13th, 2019. Paul Graduated from Concordia College, in Moorhead, MN in 1960. His advisors were Fred Finley from the Department of Curriculum and Instruction and Ken Heller from the School.

Brian J. Mitchell (B.A. Physics 1962) 1936-2018, Brian was born in Minneapolis, where he also received his M.S. degree in geophysics from the University. He did his Ph.D. in geophysics at Southern Methodist University in 1970. He was appointed to the faculty at Saint Louis University in Missouri, in 1974 and remained there until his retirement as Professor Emeritus in 2012. His research focused on seismological investigations of propagation and attenuation of Rayleigh-wave fundamental modes and overtones, and he became a widely recognized authority, publishing more than 70 papers on these topics. He was the Chief Editor of Pure and Applied Geophysics.

Continued on Page 16

Alumni Profile STUART BALE

STUART BALE

Stuart Bale is an alumnus of the School of Physics and Astronomy. He received his B.A. in Physics in 1989, his Master of Science in Physics in 1992, and his Ph.D. in Physics in 1994, all from the U. His advisor was Paul Kellogg. He is a principal investigator on the Parker Solar Probe, which launched in 2018.

Do you have any advice for new graduates just getting their start in physics?

Bale: I tell my new research (PhD) students to find an interesting corner of the field that’s not oversubscribed and dig in deep. Work hard for about five years and publish what you find. In the end, a physics education really just teaches you how to learn new things and think quantitatively about them. It’s a great education. Our students go off to start companies, work on ‘Big Data’ at Google. go into other scientific fields, etc.

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Do you see Space physics as the next big thing or is it still in the category of “not oversubscribed”?

Solar/coronal physics is going to have a golden age in the next decade. NASA, ESA, and NSF together have invested a few billion dollars. It’s not as popular as some fields. It depends where you’re working, I think, and in which subfield. We get substantial interest from new students at Berkeley. We have a very active program here that is also bringing in a lot of undergrads. It’s very encouraging to see and it makes my job easier.

There has already been substantial and exciting new research out of the Solar probe. Can you speak about that?

Ah, well, it’s a spectacular mission. A spacecraft to fly into the solar corona! We’re seeing a lot of exciting stuff. The solar wind near the Sun is much more structured and the plasma is generally unstable. Lots of small scale fluctuations, like it’s foaming or something. We can see the large-scale structure of the magnetic fields and locate their sources on the surface of the Sun. This tells us where the solar wind is emerging from. And we measure these big ‘spikes’ of s-shaped magnetic field. They’re everywhere. Probably a big piece of the puzzle of solar wind acceleration.

The FIELDS instrument appears to be holding up great. If you would have gotten that funding 20 years ago, would the group have been ready to do this or did you need the intervening years to prepare for it?

Oh - we would have figured it out. The big thing is that we

Stuart Bale (left) with Keith Goetz, University of Minnesota Research Scientist, in the clean room prior to launch, conducting final checks to make their instrument ready for flight aboard the Parker Solar Probe. Courtesy: NASA.

needed a spacecraft to get us there! So NASA had to step up and pay for that.

Is there any part of your job that you didn’t expect when you were a student?

There’s a kind of ‘business development’ side that I didn’t really appreciate. It’s like running a small company. You have to come up with ideas, sell them, generate funds, deliver on the promises, etc. Also, the ‘media’ side of things, especially for Solar Probe. I didn’t really expect that anyone outside my little sphere would be that interested in what we’re doing.

What would you advise for students wanting to learn more about “business development” or “media relations”?

Oh, I don’t know. The ‘business’ side of it is important. I come from a family of business people, so maybe I absorbed some of that along the way. The media stuff? What can prepare you for that? Acting classes? I think it’s a nice opportunity. But it makes my heart race, when I have to do it myself.

In Memoriam continued from page 14

with their pets.

Geofrey Francis Mitchell (B.S. Astrophysics 2004), 1982 - 2019, 27,Geof was born in Florissant, MO and grew up in St. Charles, MO. After graduating, he stayed in Minneapolis to work for his beloved Twins and then moved back to the St. Louis area. Geof married his wife, Elisha, in 2016. They loved cooking together, gardening, watching movies, visiting with family, and spending time

Earl William Prohofsky, (B.S. 1957), 1935 – 2019, 84, of Lakewood Ranch, Florida. Earl was born in St. Paul.

He received his Ph.D. in Physics from Cornell University in 1963. It was at Cornell where he met his wife, Susan Kaye Shapiro and they married in 1960. He taught at Purdue University for 48 years. He was honored to be a Fellow of the American Physical Society, SecretaryTreasurer of the Division of Biological Physics, and a member of the Editorial Board of AIP Books in Biological Physics. His research interests included theoretical studies of dynamics of biological macromolecules, including the critical melting of the double helix and drug attachment and dissociation. Following retirement, Earl was named Professor Emeritus at Purdue University. Earl was very active in his Jewish communities in Indiana and Florida.

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James Bernard Mehl (B.S. Physics 1961, M.S.Physics 1964, Ph.D Physics 1966 ), 1939-2019, 80, of Orcas Island, OR. Jim was born in Minneapolis, Minnesota.

Jim met his wife Joan at the University of Minnesota and they married in 1961. Jim was an Emeritus Professor of Physics, retired from the University of Delaware, where he led laboratory programs in various fields of acoustics. He also served as Department Chair and Associate Dean for Research. Since 1999, he had lived on Orcas Island in Washington State, where he continued to do computational and theoretical work in acoustic standards as well as applications of acoustic and electromagnetic resonance methods for industrial applications.

Dr. Walter C. Stolov (M.S. Physics 1951) 1928-2018, Born in Bronx, New York. Walter skipped several grades and at 16, entered The City College of New York, graduating with a BS in physics in 1948. While pursuing a Ph.D. in physics at the School, his advisor, Frank Oppenheimer, was called to testify in front of the House Committee on Un-American Activities. He was encouraged to find a new advisor, and switched to medicine.

Walter married his wife Anita in 1953. Their daughter Nancy was born in 1956, and Amy in 1959. The family moved to Seattle in 1960 where Walter joined the University of Washington’s Department of Rehabilitation Medicine, where he remained for 50 years. His research included groundbreaking work in muscle properties, electrodiagnostics, neuropathy and post-polio syndrome. He authored or co-authored more than 100 publications. He received the Distinguished Clinician Award from the American Academy of Physical Medicine and Rehabilitation in 1987 and a Lifetime Achievement Award from the American Association of Neuromuscular and Electrodiagnostic Medicine in 2001.

Pepin continued from page 7 measurement by the Curiosity rover mass spectrometer.

Pepin describes the papers that detailed that work to be among the most significant of his career.

The work on Mars samples continued through the eighties and early nineties. In 1993 Pepin began working on IDPs collected in the stratosphere by high altitude airplanes; this paralleled similar research that Al Nier and Dennis Schlutter had been conducting on IDPs for some years. Pepin’s lab merged with Al Nier’s after the later’s death in 1994. Using the noble gas profiles these labs had honed in thirty years of experience, they were able to screen out contamination by non-extra-terrestrial matter that often comprises a significant majority of the collected samples.

Pepin is in the unusual position of having worked with the man for whom the Whipple award was named. “Fred Whipple and I served together on a National Academy committee.” Meeting Whipple is partly what got Pepin interested in comets, which are likely to contain the most primordial material of anything in our solar system.

In the new millennium, Pepin began work consulting on the Mars rover missions. Curiosity closed the loop on his earlier work on Mars. When asked about the future of his field, he says that Mars will continue to play a key role. The next rover planned will take samples from around the planet and place them in a cairn where they will be loaded by another robot into a rocket for return to Earth. This mission could be a decade away, but scientists will finally have physical samples for detailed laboratory study whose origin on the planet they will know exactly. This will help them piece together some final pieces of the puzzle of Martian geology.

Ordinarily the Whipple Award is presented at the Annual Meeting of the AGU in December. Since the meeting has been cancelled, Pepin will deliver the lecture associated with the award via the internet.

Martian sunset captured by Curiosity Rover. Courtesy: NASA

A new era of solar exploration School plays key role in two new programs to study our star.

The Parker Solar Probe, launched on August 12, 2018, is traveling closer to the surface of the Sun than any previous spacecraft. Space physicists from the School contributed to the design and construction of instruments on the probe.

Instruments were designed and built by Research Director Keith Goetz and retired Researcher Steve Monson. Visiting Scholars Josh Lynch and Jason Hinze developed software for the probe. Professors Cindy Cattell, Paul J. Kellogg, and John Wygant were involved with the probe’s development.

Stuart Bale, (see profile) an alumnus of the School, is the Principal Investigator of one of the instruments on the mission.

anything that goes aboard one of those missions. At a lower tier of cost and a higher tier of risk is NASA’s suborbital programs, which include sounding rockets and high altitude balloon payloads. “Sounding rockets” are (relatively) small rockets that do not reach orbital or escape velocity. They fly straight up, launching the payload that then returns to the earth. They’re called “sounding rockets” because they use experimental instrumentation, used to develop new telescope instruments, to sound out new technologies and discovery spaces.

Professor Lindsay Glesener is Principal Investigator of the

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The University was most deeply involved with the FIELDS instrument suite which will make the first in situ measurements of the solar corona, a region of the Sun only seen in visible light from Earth when the Moon blocks out the Sun’s face during a total solar eclipse. Though the probe is only the size of a car, it was launched by the Delta rocket, one of NASA’s most powerful, because the launch energy to reach the neighborhood of the Sun is 55 times that required to get to Mars, and twice that needed to get to Pluto.

Parker Solar Probe is currently in the midst of the seventh of twenty-four planned orbits over nearly seven years. Each orbit brings the probe closer to the sun. The spacecraft will fly through the Sun’s atmosphere as close as 3.8 million miles to our star’s surface, more than seven times closer than any spacecraft has come before. (Earth’s average distance to the Sun is 93 million miles.) The journal Nature declared this “the Golden Age of Solar Exploration” in an article detailing findings from the first year of the Probe’s operation.

The School has not only contributed to the Parker Solar Probe, but is involved in solar exploration in numerous projects. There are three levels of spacecraft for solar observation: one is the big budget NASA mission, like the Parker Solar Probe. These are very restricted, in that only NASA certified technicians and experienced experts in the School such as Keith Goetz are allowed to assemble

Glesener and others at the FOXSI sounding rocket launch.

Feature Story

SOLAR EXPLORATION

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FOXSI experiment, which is a sounding rocket payload.

These payloads make short flights of 5-6 minutes and are relatively high risk, since new technology is being tested.

Still they have expectations to gather significant scientific data, and missions are planned carefully to ensure that happens. The NASA sounding rocket program has about an 85% success rate for its experiments, which represents the relatively high risk tolerance for the program. A success rate much higher would likely indicate that the experiments are not all that novel or groundbreaking. This is space physics at the graduate level, with high levels of participation from graduate students and postdoctoral scientists. Another level is the Cubesat program, which are small satellites about the size of shoeboxes. “These are ambitious efforts that often involve large student teams, and there is always the chance that something goes wrong.,” Glesener says. Undergraduates play significant roles on these projects, and indeed the most recent Cubesat, SOCRATES, was entirely student designed and built. A significant fraction of these satellites fail to respond during their flight. SOCRATES, for example has not communicated with the small satellite group. Glesener said this is pretty typical for the first Cubesat built by a university.

FOXSI is a focusing instrument that studies high energy X-rays, which normally move through objects. “For decades there was no traditional telescope that could reflect or refract high energy X-rays, but then technology developed to do direct focusing of these X-rays,” Glesener says.

FOXSI is direct focusing using mirrors with small angles of incidence. FOXSI was the first instrument to measure a focused image of the sun using high-energy X-rays.

Glesener’s group is currently working on data from FOXSI III, which launched in 2018. The team is also preparing to build FOXSI IV. This new launch is particularly exciting because it will use a sounding rocket launch facility in Alaska that allows multiple rockets to be ready on the launch pad to try to capture a major solar flare while it’s happening. The concept is to use a trigger from NASA that will indicate when a solar flare is just starting so that rockets can be launched to try to get a payload into space to capture the flare. It’s a tricky operation given that the flight time is so short and a solar flare is difficult to predict.

Glesener says that space physicists who study the aurora use this method to capture their data, but this will be the first time the method will be applied to observe solar flares.

Glesener is also working with Cindy Cattell, who is leading a paper that uses data from the Parker Solar Probe and data from extreme ultraviolet (EUV) and X-ray observations to pin down a periodic phenomenon in solar plasma. Cattell is using data from the Parker Probe and comparing it with

Glesener’s remote sensing X-ray and EUV data to confirm that the phenomenon occurs throughout the heliosphere.

Glesener says that Parker has changed everything in the field. In addition to discovering phenomena which were a complete surprise, it has prompted a new look at lots of old data.

Five Important Findings from the Parker Solar Probe Dust free zone: Parker saw evidence that there is a dust-free zone surrounding the Sun. Switchbacks: Parker has returned never before seen details about the solar wind, which contains solar energetic particles which can endanger astronauts and spacecraft. For the first time ever, Parker went to the source of solar wind. The probe observed whiplike magnetic field lines that can flip 180 degrees in a matter of seconds, these so-called “switchbacks” come in clusters and may generate clumps of plasma in the solar wind.

Turbulence: For the first time turbulence was confirmed within the solar wind, created by particles that fall back toward the sun in clumps. It has been theorized that these falling clumps of particles might be the cause of the magnetic field distortion switchbacks.

Transition zone: The solar probe observed that there is a transition point between solar winds which rotate around the sun and those that flow straight. Scientists were surprised to see this transition occurring further away from the sun than expected.

Detailed observations of solar particles: The probe showed that the Sun produces many more tiny energetic particle events than was previously believed.

Solar Switchbacks: Artist NASA’s Goddard Space Flight Center/ Conceptual Image Lab/Adriana Manrique Gutierrez

In Memoriam Walter “Cork” Johnson, 1926-2019

Hans Courant , 1924- 2019 Hans Courant was a professor at the School and founding member of the High Energy Research group. His presence extended far beyond his 34 years as a professor (1963-1997).

Professor Emeritus Walter “Cork” Johnson passed away in Minneapolis on September 24th at the age of 91. Cork was an expert on precision mass spectroscopy. A native of Minneapolis and a student of Al Nier, he received his BA, MA and PhD in Physics from the University.

After a brief stint at General Electric, Cork joined the faculty of the School in 1958 and retired in 1993.

Hans was born in Gottingen, Germany, the son of mathematician Richard Courant and musician Nina Runge, (whose father was wellHans at Los Alamos known mathematician, Carl Runge).The Courant family fled Nazi Germany, arriving in New York in 1934. Family lore has him shouting “Guten Morgen, Tante Liberty!” as their ship came into the harbor.

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Hans attended Fieldstone School upon the recommendation of family friend J. Robert Oppenheimer. Hans left in his junior year to attend MIT, but a year into his education, he was drafted into the army. He was transferred to New Mexico to work as a Special Engineer on the Manhattan Project. Hans described his work on the project as soldering circuit boards and other low level tasks.

He was a witness to the Manhattan Project’s Trinity Test in 1945.

Back at MIT after the war, he completed both undergraduate and graduate work, studying cosmic ray physics with cloud chambers. His thesis contributed to sorting out the decay modes of “S-particles” i.e. those that stopped in one of the several metal plates in the cloud chamber.

After a Fulbright Fellowship in Paris, an Assistant Professorship at Yale, and a fellowship at CERN, in Geneva, Hans joined the University faculty in 1963 with the mission to found a high-energy physics research group. After the bubble chamber technique became obsolete, Hans began working on computerized counter experiments for high energy physics. For many years, Hans served as the School’s resident resource on the application of physicsrelated toys to lecture demonstrations. Courant continued to teach for years after his so-called retirement and continued to come into work every day until the last year of his life. For younger generations of students, he’s perhaps best known as the professor who would dress as Einstein every Halloween and visit physics classes. For generations of staff he was known to make the rounds daily dispensing chocolates and friendly chit chat.

Hans loved skiing, making annual ski trips with his family through the age of of 89. In his fifties, he took up running marathons and participated in major marathons in New York and Boston.

Hans was married twice: to Maggie (Spaulding) Courant, from whom he was divorced in 1979; and to Dixie (Cardarelle Hayday) Courant, who died in 2017. He is survived by seven children and stepchildren, by 1l grandchildren and by one great-grandchild.

Cork in his lab in the 1980s.

In addition to his scientific accomplishments, Cork was dedicated to the University of Minnesota and his community. He served as Acting Head of the School of Physics and Astronomy (1969-70 and 1982-83), as well as Associate Dean (1971-77) and then acting Dean of the Institute of Technology (now CSE) from 1977-1979. Cork was one of the founders of the Honors Program in the College. He lived in the Marcy-Holmes neighborhood for almost his entire life and was very active in community affairs before and after retirement. “Cork was a stellar teacher,” said Paul Crowell, Head of the School of Physics and Astronomy. “Everyone who worked with him has commented on his dedication to the complete mission of the University.”

After retiring in 1993, Cork enjoyed traveling with his wife Harriet. He also volunteered as Treasurer of SE Seniors for 10 years, served on the Board of Faculty Volunteers, and helped with the building committee of the University Baptist Church.

His interests in art and woodworking were seen in his annual handmade Christmas cards, and in his boat building projects at the family lake cabin. His sons Bradford and Lee, daughter in law, Jessica, and grandchildren Alex and Sydney provided many opportunities for using his photography skills through the years.

Cork moved to Walker Place Methodist in South Minneapolis two years ago and enjoyed a new neighborhood, new friends, and living near the lakes. He is survived by his wife, Harriet; sons, Bradford, and Lee (Jessica); grandchildren, Alexander and Sydney; and brother, Bruce (Debbie).

In Memoriam Mikhail Voloshin, 1953-2020 Professor Mikhail Voloshin of the School of Physics and Astronomy passed away on March 20, 2020 from heart failure. He had been fighting lymphoma for some time. Misha was born in Bucharest, Romania, in 1953, and grew up in the former Soviet Union. At age 17 he won a gold medal for the Soviet team at the International Physics Olympiad.

He attended Moscow School 57 (a secondary school known for its specialized curriculum) and graduated with a physics degree in 1970. He received his Masters in physics from the Moscow Physics and Technology Institute in 1976 and his Ph.D. the following year from the Institute of Theoretical and Experimental Physics (ITEP) in Moscow. In graduate school he became one of the world pioneers of quantum chromodynamics (QCD) and one of the creators of heavy quark theory.

S C H O O L O F P HY S I C S & A S TR O N O MY ❈ 2 0

Misha joined the faculty at the William I. Fine Theoretical Physics Institute (FTPI) at the University of Minnesota in 1990, while continuing his affiliation with ITEP. His research topics over the years included: quantum properties of semiclassical field configurations, decay of a metastable vacuum, QCD sum rules, nonperturbative gauge dynamics, physics of heavy quarkonium, properties of hadrons with open heavy flavor, and nonstandard properties of neutrinos. His most recent work is a continuation of the studies of the properties of hadrons containing heavy quarks and also studies of properties of semiclassical field configurations.

His colleague Mikhail Shifman wrote of him, “Misha’s career started right around the time of the discovery of the J/psi in November 1974 (The November Revolution). He became one of QCD’s leading practitioners. He was a standard bearer in this area till his last days. He was a resource for both experimentalists and theorists throughout the world. He combined extremely high standards and principles with passion for physics as an experiment-based science. He hated questionable arguments and unsubstantiated assumptions.”

Misha received the USSR Academy of Sciences Medal and Award in 1983, the J.J. Sakurai Prize for Theoretical Particle Physics from the American Physical Society (APS) in 2001, and the Alexander von Humboldt award for a senior U.S. scientist in 2003. He was made an APS Fellow in 1997. He authored 265 academic papers and served as the director of FTPI for six years.

Misha is survived by his wife, Natalia and his two sons Alexei and Mikhail, all of whom live in the Twin Cities.

Friends and colleagues of Misha have established a fellowship in his memory to benefit graduate students in theoretical or experimental high energy physics. For more information, please visit the William I. Fine Theoretical Physics Institute’s homepage at https://cse.umn.edu/ftpi.

Cecil “Jake” Waddington, 1929-2020 Emeritus Professor Jake Waddington of the School of Physics and Astronomy passed away on October 1, 2020. He was 91 years old. Jake was born on July 6, 1929 in Cambridge, England.

He attended Summerhill, a famous progressive school, graduating in 1947. Jake earned his B.Sc in 1952 and doctorate in 1956. His thesis was on the use of nuclear emulsions to study cosmic rays, under the guidance of C.F. Powell and Peter Fowler. His wife, Jean earned her B.Sc in 1956 and they married that same year.

In 1957 Jake came to the University as a research assistant. He joined a strong group of space physicists including Ed Ney, Phyllis Freier, Jack Winckler and Paul Kellogg. During this period he began a long collaboration with Professor Phyllis Freier that continued after Jake spent a year back in Bristol and six months at the Goddard Space Flight Center in Washington. Jake returned to Minnesota in 1962 as an Associate Professor and was promoted to full Professor in 1968. He continued working on cosmic ray research, mostly based on balloon flights from Fort Churchill, Canada, Texas, and India. He also began a research program to look for gamma ray sources, using spark chambers and electronic counters flown in balloons.

In 1972, Jake returned to England for a sabbatical year at Imperial College London, where he studied heavy cosmic ray nuclei. Upon returning to Minnesota, he began working on a detector to be flown on NASA’s High Energy Astronomical Observation satellite (HEAO). There were several generations of this detector through the 1970s. Jake became one of the world’s leading experts in fragmentation of relativistic heavy nuclei as a result of his work on this program.

In 1980 Jake received a medal from NASA for his service to the HEAO program and continued to work as a consultant to the agency during the following decade. In retirement, he remained active in research, including balloon-borne experiments in the Antarctic. Over the years Jake published over 190 scientific papers and helped guide many graduate students through the program at the University. Perhaps owing to his slightly unorthodox education at Summerhill, Jake adopted a teaching style which encouraged a hands-on approach to learning and was more reflective of the real world of physics. For example, students were expected to read current journal articles and present the information to the class, something that wasn’t typical at the time. This was sometimes controversial, but its effectiveness was evidenced by several absolutely glowing letters from students sent to various department heads over the years. Jake was particularly pleased that he had successfully nurtured so many women graduate students to careers in physics.

Jake was a dedicated sailor and held the title of “Commodore” at the Calhoun Yacht Club. He and his wife Jean, who survives him, gave an annual Christmas party for the faculty of the School.