He jishu (Oct 2021)
Efficiency calibration of lanthanum bromide scintillation detector and analysis of influencing factors of the detection efficiency
Abstract
BackgroundActive efficiency calibration of radiation detector requires the multiple standard radioactive sources with different energies, and the measurement condition of the standard sources need to be consistent with sample sources. Due to the limitation of these experimental conditions, it is difficult to achieve efficiency calibration of detectors effectively in ordinary laboratories.PurposeThis study aims to solve the above problems by simulation and experimental test.MethodsFirst of all, Monte Carlo software MCNP (Monte Carlo N Particle Transport Code) was used to explore the influences of detection efficiency for a lanthanum bromide scintillation detector corresponding to the simulated energy of 0.662 MeV of 137Cs source. Influencing factors such as Al shell thickness, MgO reflector thickness and crystal size of LaBr3:Ce (ø3.18 cm×10.16 cm) detector on full-energy peak efficiency were calculated. Then, passive full-energy peak efficiency calibration of the detector was carried out by the MCNP, and the simulation results were compared with the ones of theoretical calculation and measurement.ResultsThe full-energy peak efficiency decreases with the increase of thicknesses of the Al shell in end-face and the MgO reflector, and thickness of the cylindrical Al shell has little effect on that. The full energy peak efficiency raises with the increase of the crystal length and radius of the detector, and the effect of the radius on the full-energy peak efficiency is more obvious than that of the length. The errors between the simulation and the theoretical calculation as well as the measurement results are within 7% and 6%, respectively.ConclusionsThe accurate of simulation results proves the correctness of efficiency calibration in this study which provides reference for the laboratory to perform passive efficiency calibration.
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