Bulk GaAs as a solar neutrino detector

A GaAs detector may offer the unique possibility to independently study neu trino properties and solar physics. The ability to measure the flux of p-p, Be-7 and pep solar neutrinos would allow one to approach a solution of the "solar neutrino problem", i.e, the explanation of the significant deficit in observed capture rate of solar neutrinos. A large GaAs solar neutrino de tector would allow to measure parameters for possible Mikheyev-Smirnov-Wolf enstein neutrino oscillations with unprecedented precision. A model-indepen dent test for sterile neutrinos is also possible. A direct measurement of t he temperature profile of the sun center appears feasible. A GaAs detector would also provide the ability to observe neutral current interactions in a ddition to addressing a wide range of other interesting physics. In order to measure the p-p, pep and Be-7 neutrinos a detector is required with low threshold (< 350 keV), good energy resolution (< 2 keV) and low ba ckground. A GaAs solid-state detector could meet the listed requirements. A large GaAs detector would be composed of approximately 40,000 intrinsic Ga As crystals, each weighting 3.2 kg. Such a detector would have a mass of 12 5 ton and would contain 60 ton of Ga occupying a volume of roughly 3 m on o ne side. Previous efforts by many groups have resulted in producing very sm all detectors with reasonably good resolution. However, it has thus far pro ved impossible to make large detectors with good resolution. Thus, a solar neutrino detector such as the one described above is obviously very ambitio us, but the scientific motivation is sufficiently high that we have begun a research and development program with the goal of determining the technica l feasibility of constructing large GaAs crystals with the requisite electr onic properties to serve as particle detectors. <(c)> 2001 Elsevier Science B.V. All rights reserved.