Low Background Liquid Scintillation Counting Using an Active Sample Holder and Pulse Discrimination Electronics

Abstract

A Packard low-level liquid scintillation counting system is described which provides superior low-background beta-counting capability for 3H and 14C. The design is based on a novel pulse-discrimination circuit that separates background from valid scintillation pulses. Background discrimination is further enhanced by adding a plastic vial holder that acts as an anticoincidence guard. When excited by background radiation, the scintillation properties of the plastic provide an increased burst of photons to the detection electronics, which discriminate based on the number of component pulses in the burst. Experimental data demonstrate the low-level counting capabilities of this counter.