Time pickoff methods for BGO crystals in Ge-BGO Compton suppression spectrometer systems

Abstract

Three methods for generating the veto signals from BGO Compton suppression shields were compared. The methods utilized (a) a current pulse, (b) a fully integrated pulse and (c) a partially integrated pulse with time constants of 50, 100 and 200 ns, respectively. The counting efficiency for low energy γ-rays ( 241Am source), the time delay and the time jitter of the output pulse were measured. The comparison showed that triggering by the partially integrated pulse with a time constant of 200 ns is superior as it combines a high triggering efficiency with a short delay of the response and a small time jitter.