Utilization of a GaGe CompuScope 1012 computer-based oscilloscope for pulse shape discrimination and radiation spectroscopy

Abstract

Systems for digitally processing pulse waveforms from radiation detectors are currently under development and are designed to replace conventional pulse height, analog-to-digital converters. These systems are capable of capturing a complete radiation-induced pulse in digital form. Subsequently, all the pulse features can be analyzed digitally (e.g., pulse validation, energy information through digital integration of the pulse, dynamic threshold determination, pulse duration, pulse shape analysis, and noise reduction). This paper describes implementation of such a system using a GaGe CompuScope 1012, 12-bit, 10-MHz computer-based oscilloscope card. This card is designed to function as a dual channel, 12-bit, 10-MHz, digital oscilloscope or a single channel 20-MHz oscilloscope. The system contains 1 megabyte of on-board memory and allows transfer of this data to computer memory at a rate of 1.5 megawords/s in a 486-class computer. The computational time required to perform digital pulse integration and cross-correlation pulse shape discrimination has also been determined. Combining the data transfer rate with this computational time results in throughput rates of approximately 7000 counts per second for typical data acquisition modes. Applications for this system include alpha/beta/gamma-ray discrimination in phoswich detectors, alpha/beta discrimination in CsI scintillators and neutron/gamma-ray discrimination in BF 3 probes, proton recoil gas-filled detectors, and organic liquid scintillation detectors.