A PORTABLE, PHOTON ANALYSIS SPECTROMETER FOR THE ASSAY OF X-RAY AND GAMMA-RAY EMITTING RADIONUCLIDES

A portable, battery-powered, multichannel analyzer (MCA) for use with Ge spectrometers has been developed for in-field use for the assay of x- and gamma-ray emitting radionuclides. The spectrometer is capable o f operating to rates greater than 150,000 counts per second. The analy zer is a Canberra InSpector MCA, that is equipped with the INEEL ultra -stable dual-energy pulser, and pulse injection with subsequent remova l (PISR) circuitry. PCGAP, a set of MCA control and spectral analysis programs, was developed for use on a PC with a Windows NT Operating Sy stem. It includes an interactive peak analysis program as well as auto matic spectral analysis programs for the X- and gamma-ray regions, and a number of utility programs. The pulser peaks are calibrated with ra dioactive sources in terms of energy (i.e., their energy equivalents a re measured) using the PCGAP spectral analysis package so that energy shifts, including those due to changes in temperature or count rate, d o not cause a loss of energy calibration. The number of injected low- and high-energy-equivalent pulses is known so the stored pulser pulses can be used for a dead-time and random summing correction. The pulser peaks are also used to monitor any deterioration in spectral quality caused by noise, ground loops, etc. The results of performance tests t o demonstrate the capabilities of this pulser-equipped InSpector are r eported.