He jishu (Jun 2024)
Position resolution performance of a position-sensitive 3He proportional counter based on a time-difference method
Abstract
BackgroundNeutron localization technology can be used for monitoring spent fuel reprocessing to prevent nuclear criticality accidents.PurposeThis study aims to investigate the effects of different neutron emission modes, 3He pressure, tube diameter, and moderators on the position resolution and detection efficiency of a position-sensitive 3He proportional counter.MethodsFirstly, a 3He proportional counter with a tube diameter, tube length, and 3He pressure of 2.54 cm, 80 cm, and 405 300 Pa, respectively, was taken as object of study, and the Monte Carlo (MC) algorithm was employed to simulate the effects of neutrons with different energies, neutron emission modes, 3He pressures, tube diameters, and moderating bodies on the position resolution and detection efficiency of a position-sensitive 3He proportional counter. Then, the effects of the time difference of arrival (TDOA) on the location of a source in an active zone, source to tube distances, thickness of moderating body, and position resolution of the 3He proportional counter were investigated. Finally, a linear fitting analysis of the active region was performed, and the locations of inactive regions were estimated to determine the positioning ability of the 3He tube.ResultsSimulation results show that the position resolution of this 3He proportional counter is equal in all axial sections, and the position-resolution limit of thermal neutron source is 0.17 cm. When the thickness of the moderating body is 5 cm, and the 244Cm source is close to the external wall of the moderating body, the neutron detection efficiency is 3.0%, and the theoretical position resolution is 9.25 cm whilst experimental result of position resolution is 18.50 cm, half of the theoretical value, and the location resolution limit is 2.64 cm after processed by the linear fitting curve of the active location and a time-difference crest.ConclusionsMC simulation and experimental tests show that the position-sensitive 3He proportional counter exhibits better position resolution and detection efficiency for the 244Cm source when the thickness of the moderating body is 2~3 cm, hence suitable for practical applications.
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