overview
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I received my B.S. from the Massachusetts Institute of Technology in 1981, and my Ph.D. from the University of California, Berkeley in 1986.  I joined the UCI Physics Department in 1990.  I was awarded the NSF Young Investigator Award in 1992, and the UCI Research Faculty Fellowship in 1991 and 1993.

research summary
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Collaborators at UCI: Patrick Mock, Rodin Porrata, and Eric Schneider

My research program investigates questions in the interdisciplinary fields of cosmic rays, neutrino astro-physics, and ultra-high-energy (UHE) gamma ray astronomy. Do astro-physical sources of high-energy neutrinos exist? What is the most cost-efficient way to construct large neutrino detectors, since unprecedented sensitivities will be required to search for astrophysical sources of neutrinos? How can the sensitivities of air shower arrays be improved? What can the spectra of cosmic ray antimatter tell us about dark matter? Our group uses a variety of experimental techniques to help answer these questions. First, we will measure the flux of cosmic ray positrons and antiprotons using a balloon-borne spectrometer called HEAT (High-Energy Antimatter Telescope). Second, we are constructing a large neutrino telescope at the South Pole. The primary science objective of the HEAT project is to measure the energy spectrum of positrons in the cosmic radiation between 5 GeV and 50 GeV. The existing data on the positron spectrum exhibits an unexpected increase at energies greater than 10 GeV. Several explanations have been postulated for this spectral feature by introducing new primary sources of positrons such as (1) pair production by gamma rays in the strong magnetic fields of pulsars, or (2) positron- electron pair production from the annihilation of dark matter in the galactic halo. Our group at UCI is responsible for the design and construction of an electromagnetic calorimeter in the HEAT payload. It is designed to reject hadrons at the few percent level and measure the positron energy to about 10 percent. The first of two launch missions is planned for early 1994.

The field of neutrino astrophysics has grown dramatically over the past decade, but due to its relative youth, no telescope exists that is dedicatedto the study of high- energy neutrinos from astrophysical sources. It is for this reason that we are constructing the AMANDA (Antarctic Muon and Neutrino Detector Array) detector which will have a sensitive area that is over one order of magnitude larger than the largest of present generation detectors. We will embed an array of sensors within the polar ice cap to sense the Cherenkov light emitted from neutrino-induced muons. The AMANDA technique provides an intriguing way to search for astro-physical sources of high-energy neutrinos because it relies on an abundant and natural resource, south polar ice. Recent measurements by physicists at UCI and collaborators from UC Berkeley and the University of Wisconsin, Madison, of South Polar ice at depths of 800 meters suggests that the maximum attenuation length of ice exceeds 24 meters. These studies also indicate that the ice has no sources of background light and that our optical sensors survive deployment. Five prototype AMANDA sensors have been in continuous operation for more than a year. These results are so encouraging that NSF has recently approved our AMANDA proposal to construct a neutrino detector with an effective area of 10,000 m^2. We expect to complete the construction by 1995.

:: Neutrino Astronomy on the 1 km2 scale, S. W. Barwick et al., J. Phys. G: Nucl. Part. Phys. 18, 225 (1992).

:: HEAT: High Energy Antimatter Telescope, D. Muller et al., Proceedings of the 22nd International
   Cosmic Ray Conference, p. 177.

:: Transparency of Antarctic Ice: First Results, S. W. Barwick et al., to appear in Proceedings of
   Workshop on High Energy Neutrino Astrophysics, p. 291.

:: Hardware design and Prototype Tests of the AMANDA Neutrino Detector, D. Lowder et al., Proceedings
   of the 23rd International Cosmic Ray Conference.

AMANDA South Pole, water Cerenkov neutrino detector