Brochure: Experimental High Energy Astrophysics Program

The University of Utah has a long standing tradition of excellence in cosmic ray research, extending back to the Park City mine experiments of the late 1960’s led by the late Prof.

Jack Keuffel.

This observatory searched for astrophysical sources of high energy neutrinos as well as phenomenological aspects of cosmic ray physics.

Since this experiment, the University of Utah has hosted numerous experimental astrophysics programs, including the Fly’s Eye Experiment (19761992), the Utah UHE surface array (1986-1990), CASA-MIA (Chicago Air Shower Array and Michigan muon Array), DICE (Dual Imaging Cherenkov Experiment), and BLANCA (Broad Lateral Non-imaging Cherenkov Array. Utah faculty have been involved with the design, construction, and operation of a series of next-generation instruments, including HiRes (the High Resolution Fly’s Eye, 1990-2006), Telescope Array, the Pierre Auger Cosmic Ray Observatory, the VERITAS gamma ray observatory, the Milagro gamma ray observatory, the MAGPIE balloon experiment, and the CGRO, AMS, and GLAST satellite experiments.

Observatories

Gamma Ray Astronomy/VERITAS www.physics.utah.edu/gammaray http://veritas.sao.arizona.edu HAWC Gamma-Ray Observatory www.hawc-observatory.org

Experimental High Energy Physics & Astrophysics

South Physics Observatory www.physics.utah.edu/observatory StarBase Observatory www.physics.utah.edu/starbase Telescope Array www.telescopearray.org W.L. Eccles Observatory www.physics.utah.edu/weo W.M. Keck Observatory www.telescopearray.org/tara/index.html 201 James Fletcher Bldg.

115 South 1400 East Salt Lake City, UT 84112-0830 (801) 581-6901

Dept of Physics & Astronomy University of Utah www.physics.utah.edu www.astro.utah.edu

TARA Array

Cosmic Ray Research The history of cosmic ray research is a story of scientific adventure. For over a century, cosmic ray researchers have climbed mountains, ridden hot air balloons, and traveled to the far corners of the Earth in order to understand these fast-moving particles from space. They have solved some scientific mysteries and revealed many more. With each passing decade, scientists are discovering higher-energy, increasingly rare, cosmic rays.

TARA Array The Telescope Array Radar (TARA) project is one way in which Telescope Array Scientists are looking towards the future of cosmic ray research. The goal of TARA is to create the world’s first radar observatory for ultra-high energy cosmic rays. Like radar systems used in tracking airplanes or cars on the highway, TARA works by detecting the deflection of radio waves by the cosmic ray-induced atmospheric ionization. TARA scientists will first try to identify the radar echoes of cosmic ray ionization trails. Then, they will use these echoes to test models of radar scattering and to learn to extract the astrophysically interesting characteristics of cosmic rays.

Telescope Array Project The University of Utah is the home institution for the Northern Hemisphere’s larges cosmic ray observatory.

Dubbed Telescope Array, the observatory aims to study the most energetic subatomic particles from space. Telescope Array was constructed and is maintained by over 100 physicists from Japan, the United States, Korea and Russia. Data taking began in 2007.

The highest energy cosmic rays pack as much energy as a golf ball driven down a fairway, and they strike Earth at a rate of one per square kilometer per century. Telescope Array currently covers 730 square kilometers of Utah’s West Desert in order to capture these rare particles. The cosmic rays are observed using three nitrogen fluorescence telescopes and a separate ground array consisting of over 500 scintillation detectors.

TALE While Telescope Array studies cosmic ray particles with energies above 1018 electron-volts (1 EeV), there remain unanswered questions about the cosmic ray energy spectrum and composition at lower energies. Enter the Telescope Array Low-Energy extension (TALE). TALE uses both fluorescence and surface array detectors - similar to Telescope Array - but with varied telescope pointing directions and surface array spacing so as to optimize the detection of particles with energies below 1 EeV. Together, TA and TALE aim to provide seamless coverage over four orders of magnitude in the cosmic ray energy spectrum.

VERITAS Gamma Ray Observatory VERITAS (Very Energetic Radiation Imaging Telescope Array System) is a ground-based gamma ray observatory with an array of four 12m Imaging Atmospheric Cherenkov Telescope (IACT) located at the Mt. Hopkins base camp site in southern Arizona.

The array allows images of the same shower to be recorded

from different view points. This leads to reconstruction of the primary particle with great precision and discrimination against cosmic rays.

The gamma ray sky brings us information about the most violent phenomenon in the universe, from super-novae and their possible role in cosmic ray acceleration to the accretion of material onto super massive black holes in distant galaxies. It is also a window through which the most intriguing questions of astrophysics can be addressed, such as the nature of dark matter and dark energy in the universe.

HAWC

The University of Utah is a partner of the High Altitude Water Cherenkov Observatory (HAWC) Collaboration. HAWC uses an array of large water tanks to detect charged particles created by gamma-rays and cosmic rays. These particles exist only at high altitudes, so the HAWC observatory is being constructed at 14,000+ ft above sea level in central Mexico. When particles from the shower pass through the water, they emit Cherenkov light because they travel faster than the speed of light in water. HAWC will be able to observe source of gamma-rays and cosmic rays both day and night, and during inclement weather, thereby expanding upon the capabilities of the optical detection technique employed by VERITAS.