Technical Physics [1]. However, this method does not permit identifying either the material itself or its isotopes. The identification can be made from measurements of the spectrum of the γ rays emitted by the material in the energy range 0.1-1 MeV [2]. Methods for detecting and identifying γ-emitting fissioning material and its isotopes, including under field conditions, on the basis of analysis of the measurements of the neutron and/or γ rays in wells drilled near the proposed location of the material have been developed at the Russian Federal Nuclear Center -All-Russia Scientific-Research Institute of Technical Physics. In the mathematical simulation of the experiment, and choosing the form of the material and the intensity of the radiation, the PRIZMA.D program with the BAS library and the MCNP program with the ENDF-BV library, which were verified on calibrated experiments, were used to obtain the best agreement between the computed and experimental dependences obtained by detecting neutrons and γ rays.The calibration experiments (2001 and 2003) on detecting fissioning material in soil were performed under laboratory conditions using measurement cavities with sand simulating "infinite" soil. In the experiments, the density of the sand was measured, the chemical composition of the sand was investigated, the water content was determined, and the measurement errors were estimated. The γ-ray source was assembled from several small objects of fissioning material. A γ spectrometer with a coaxial semiconductor detector GX3019 made of 50 × 50 mm germanium with energy resolution 0.8 keV/channel (E γ = 122 keV), relative detection efficiency 32%, and a γ spectrometer with a scintillation detector with 40 × 40 mm NaI(Tl) single crystal with energy resolution ~10% in the energy range 350-450 keV (BDÉG-20R), and an analyzer based on an ATsP-8K-2M spectrometric amplitude-to-digital converter, were used for detection.The semiconductor spectrometer gives better energy resolution and makes it possible to detect and identify fissioning material at large distances, but it requires expensive hardware and software, and the detector must be cooled with liquid nitrogen. The scintillation spectrometer with a NaI(Tl) crystal makes it possible to use relatively simple hardware in a wide temperature range, it is smaller and can be used in small wells, but its energy resolution is worse. To search for fissioning material under field conditions, the neutron method and both spectrometers should be used; the scintillation spectrometer is best used for rapid detection of anomalies in the background radiation and the semiconductor spectrometer is best used for careful identification of these anomalies. When the counting rate of the scintillation detector exceeds the background in the
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.