Sample Sandwiched Plastic Scintillators for Activation Measurements by Use of Fast Neutrons

Abstract

Plastic scintillator plates sandwiched between thin radioactive samples were viewed with two photomultipliers and the coincident outputs were measured. For β - -rays, the pulse-height distributions showed approximately triangular shapes and the pulse-height endpoints were proportional to their maximum energies. Similar characteristics were also found in the case of γ-rays. The counting efficiencies were empirically determined as functions of radiation energies in both cases. The sandwich scintillators having aluminium, copper or silver foils as samples were exposed to 14 Mev neutrons and the induced activities of the samples only were counted effectively. Thus the Al 27 ( n , p ), Cu 63 ·( n , 2 n ) and Ag 107 ( n , 2 n ) reaction cross sections were obtained with small standard deviations. Other applications are suggested.