Gamma-ray spectrometric equipment for detecting nuclear materials

Abstract

The paper describes a gamma-ray spectrometer and reports on its primary parameters. The base of the spectrometer is two cylindrical detectors filled with compressed xenon, whose energy resolution is 14-15 keV at 662 keV. Software developed to control the gamma-ray spectrometer and to process experimental data is also described in brief. Measurement results of gamma-ray radiation from isotopes of plutonium and uranium are given. Measurements were conducted for various time exposures. It is shown that using this equipment, one can detect and identify a single gram of plutonium within several seconds at a distance of 1 m. Possibilities of the gamma-ray spectrometer application in order to accomplish control over displacement of fissile materials are considered.

<title>Identification of hidden fissile materials using high-pressure xenon gamma-ray detectors</title>

“…Over the last twenty years, various types and configurations of HPXeD have been developed at Moscow State Engineering and Physics Institute (MEPhI) [3]. Today the HPXeD, based on cylindrical ionization chambers with a Frisch grid, seem to be the most promising detectors.…”

Simulation of Experiments with Pressurized-Xenon γ-Ray Detectors

“…One application developed on the basis of this method is the virtual gamma-spectrometric laboratory GammaLab [1, 2], which makes it possible to simulate the spectra obtained for point and volume sources with an arbitrary radionuclide composition using semiconductor and scintillation detectors. The resolution of the new detectors, based on LaBr, LaCl, or pressurized xenon and developed at the Moscow Engineering Physics Institute [3,4], is lower than that of detectors based on ultrapure germanium, but they are free of drawbacks such as the need for low-temperature cooling and high cost, and their resolution is approximately 5 times higher than that of NaI scintillation detectors.The present article analyzes the possibilities of using gamma spectrometers based on pressurized xenon for quantitative analysis of samples with a complex radionuclide composition using the GammaLab program system and presents the principles and results of the simulation of experiments using a pressurized-xenon gamma-ray detector.The simulation consists in calculating the radiation spectrum of a source at the position of the detector, converting the spectrum taking account of instrumental effects, and transferring it into an external program for display and further processing. A possible variant of a solution of this problem is to use the Monte Carlo method to play out the decay chain of the radionuclide and radiation transfer in the container and detector materials.…”

“…One application developed on the basis of this method is the virtual gamma-spectrometric laboratory GammaLab [1, 2], which makes it possible to simulate the spectra obtained for point and volume sources with an arbitrary radionuclide composition using semiconductor and scintillation detectors. The resolution of the new detectors, based on LaBr, LaCl, or pressurized xenon and developed at the Moscow Engineering Physics Institute [3,4], is lower than that of detectors based on ultrapure germanium, but they are free of drawbacks such as the need for low-temperature cooling and high cost, and their resolution is approximately 5 times higher than that of NaI scintillation detectors.…”