ISOTOPICALLY ENRICHED GERMANIUM DETECTORS FOR ASTROPHYSICAL GAMMA-RAY SPECTROSCOPY

A study is presented of the instrumental background in astrophysical gamma-ray spectrometers using isotopically enriched germanium detectors. Calculations show that the beta-decay background, which is the largest component between ∼ 0.1 and 1.0 MeV in balloon-borne and satellite spectrometers, is dominated by the activation of 74Ge. This component can be reduced by an order of magnitude using detectors enriched to > 80% in 70Ge. The predicted reduction in the total background for current balloon-borne instruments is more than a factor of 1.7 between 0.2 and 1.0 MeV. For future satellite instruments, the reduction in this energy range is by more than a factor of 5. © 1990.