The All Germanium Anti-Compton Spectrometer

A two crystal Ge(Li) detector system has been developed for use as an anti-Compton gamma-ray spectrometer. The basic components of this system are a pair of Ge(Li) detectors mounted in tandem. Coincidence techniques are used to require a gamma ray to interact by multiple processes (e. g. one or more Compton events followed by a photoelectric event) in each portion of the pair of detectors. The total energy deposited is then recorded. Energy absorbed by a single process (e. g. one Compton event) is not recorded. The resulting spectrum is made up of full energy peaks above a low and featureless background characterized by the absence of Compton edges. An investigation of the efficiency and peak-to-background ratio as a function of gamma ray energy has been made for this new gamma-ray spectrometer.