Segmentation and Pulse Shape Discrimination Techniques for Rejecting Background in Germanium Detectors

We examine the possibility of rejecting the internal ß-decay background in coaxial germanium detectors by distinguishing between the multi-site energy losses characteristic of photons and the single-site energy losses of electrons in the range 0.2 - 2 MeV. The photon transport was modeled with a Monte Carlo routine. We investigate background rejection by both multiple segmentation and pulse shape discrimination techniques. The efficiency of a six 1 cm-thick segment coaxial detector operating in coincidence mode alone is compared to that of a two-segment (1 cm and 5 cm) detector employing both front-rear coincidence and PSD in the rear segment to isolate photon events. Both techniques can provide ¿95% rejection of single-site events while accepting ¿80% of the multi-site events above ~500 keV.