Standardization of sup(241)Am by means of coincidence system using 4 pi plastic scintillator detector

Abstract

A 4nt (a,(3)- y coincidence system using a plastic scintillator detector in 47t geometry has been developed and applied for the standardization of 241Am. The scintillator shape and dimensions have been optimized for maximum charge particle detection efficiency, while keeping background low and a nearly constant gamma ray efficiency for different points at the radioactive source. The gamma ray events were measured with 3" x 3" NaI(Tl) scintillation counter. The electronic system for processing pulses consisted of logic gates and delay modules feeding a Time to Amplitude Converter with output to a Multichannel Analyser. The alpha detection efficiency measured with 241Am resulted around 95% and the beta detection efficiency measured with 60Co was around 60%. Activity measurements of 241Am were compared with a conventional system employing a 4it proportional counter and showed good agreement.