SIMULTANEOUS COUNTING OF ALPHA-RAYS, BETA-RAYS AND GAMMA-RAYS WITH PHOSWICH DETECTORS

Phoswich detectors for simultaneous counting of alpha, beta and gamma rays have been developed, which were prepared by combining two or thre e scintillators, ZnS(Ag), NE102A and/or BGO or NaI(TI), with different rise times from each other. In order to adjust the pulse height ascri bed to each scintillator within a dynamic range, a sheet of Au-Mylar w as used, if necessary, as an optical neutral density filter for loweri ng the transmittance of scintillation of the ZnS(Ag). Characteristics of these phoswiches were examined by a pulse shape discrimination tech nique. Excellent discrimination among the radiations was attained for the prepared phoswiches.