Neutron-damaged GaAs detectors for use in a Compton spectrometer

Detectors made of GaAs are being studied for use on the focal plane of a Compton spectrometer which measures 1 MeV to 25 MeV gamma rays with high energy resolution (1% or 100 keV, whichever is greater) and 200 ps time resolution. The detectors are GaAs chips (Cr-doped or un-doped) that have been neutron-damaged to improve the time response. The detectors are used to measure fast transient signals in the current mode. The properties of various GaAs detector configurations are being studied by bombarding sample detectors with short pulses of 4 MeV to 16 MeV electrons at the Linac Facility at EG&G Energy Measurements, Inc., Santa Barbara, California Operations. Measurements of detector sensitivity and impulse response versus detector bias, thickness, and electron beam energy and intensity have been performed and are presented.