Pulse shape discrimination system for room-temperature semiconductor detectors

Easily adjustable pulse shape discrimination (PSD) system effectively opera ting in the wide range of registered energies is offered. Shape distortions of the detector output signal due to charge losses are clearly visible if one carries out shape analysis of the spectrometric signal for pulses resto red up to the rectangular shape. The essence of the method consists in the analysis of difference of a restored signal form from rectangular. For this purpose the area of a pulse is measured within the given interval at once after incoming pulse and within the same time interval delayed concerning f irst. In case of an inequality of these areas, the signal is considered def ormed and is not exposed to further analysis. Schematic decision and operat ion mode of PSD system is analysed, pulses diagrams are presented. The deve loped PSD system was applied in gamma-spectrometer with planar geometry CdT e detector with dimensions 5 x 5 x 3 mm(3). Detector had m-s-m structure wi th gold electrode. Initial energy resolution of the detector was 17keV at 6 62keV and peak-to-Compton ratio equal to 1.8. The PSD application improves energy resolution up to 3.2 keV and peak-to-Compton ratio to about 5.0. At this essential reduction of count rate (up to 75%) in a maximum of a total absorption peak is observed. But the energy resolution of about 6 keV can b e received at insignificant (not more than 20%) reduction of count rate. Sp ectra of Cs-137 and Ba-133 obtained with and without PSD system application are shown. Diagrams of energy resolution at 662 keV line as well as count rate in the total absorption peak maximum versus pulse shape discrimination level are presented. (C) 2001 Elsevier Science B.V. All rights reserved.