Laboratory tests and simulations of pulse shape discrimination (PSD) technique for background reduction in germanium gamma-ray detectors

摘要

Abstract: For actively shielded, narrow aperture germaniumspectrometers at balloon or spacecraft altitudes, thebeta decay of radio-active nuclei is the dominantsource of background in the 0.2 to 2 MeV energy range.This component of the background is internal to thegermanium detectors (GeDs) and results from theactivation of Ge nuclei by cosmic ray secondaries. Thesensitivity of GeD spectrometers can be improved byrejecting beta-decay events, which deposit energy at asingle site in the detector, while retaining photonevents, which are predominantly multiple site at theseenergies. Pulse shape discrimination (PSD) techniquescan distinguish between single- and multiple-siteevents by analyzing the shape of GeDs' current pulses.Here we present results of laboratory tests of PSD witha newly developed narrow-inner-bore (0.6 cm diameter)coaxial GeD and compare them to numerical simulations.!12