Dual parameter analysis of CsI:Tl/PMT with a digital oscilloscope

Scintillation pulses from alpha-particle and gamma-ray excited CsI:Tl were recorded with a photomultiplier tube and digital oscilloscope card in single parameter (pulse shape or pulse height) and dual parameter (simultaneous pulse shape and pulse height) modes. A 2.8×1.3×1.3 cm3 CsI:Tl crystal was coupled to a Burle 8850 photomultiplier tube (PMT) and excited with 148Gd (Eα=3.18 MeV) and 137Cs (Eγ=0.662 MeV). The timing pulses (50 Ω terminated dynode signal) from the PMT base were directly input to a GaGe CompuScope 8012A/PCITM (12-bit, 50 MHz dual channel digital oscilloscope card) that resided in a P6-300 MHz personal computer. Individual digitized pulses were processed via a LabVIEWTM V 4.1 interface to the oscilloscope. The ratio of the charge collected over a short time interval to the total charge collected was used for the single parameter pulse shape spectrum while the total charge collected was used for the single parameter pulse height spectrum. The dual parameter spectrum was produced by displaying the pulse shape and pulse height information for individual pulses on a 2-D grid. The digital oscilloscope with LabVIEWTM interface offers a versatile data acquisition system for pulse shape, pulse height and dual-parameter analyses.