RESUMEN
Objective To establish a sourceless efficiency calibration method by coupling Monte Carlo simulation with analytical calculation. Methods Monte Carlo simulation was used to calculate the point-to-point detection efficiency of specific detectors to establish a detection efficiency grid. The detection efficiency of point source, disc, cylindrical, beaker, spherical, U-tube and Marlin cup samples was analyzed using numerical integration method after detection efficiency grid interpolation. Results The above coupling method was used for sourceless efficiency calibration. Within the energy range of 0.2–3 MeV, the relative deviation of calibration between coupling method and Monte Carlo simulation was mostly less than 10%, the maximum relative deviation was 18.06%, and the computation time was reduced by at least 86%. The above coupling method was used for sourceless efficiency calibration of an HPGe detector manufactured by ORTEC for point source detection, which was in good agreement with the experimental calibration, and the relative deviations were less than 10%. Conclusion This method can be generalized and used in the sourceless efficiency calibration of HPGe, LaBr3, and NaI detectors.
RESUMEN
Objective To optimize the Marinelli beaker with the simulation of Laboratory Sourceless Object Calibration Software (LabSOCS), to investigate the detection efficiency of HPGe detector in measuring noble gas, and to provide a reference for the measurement and optimization of noble gas effluent from nuclear power plants. Methods LabSOCS was used to establish a Marinelli beaker model to investigate the relationship of gamma ray detection efficiency of noble gas with gas components, gas density, size and volume of the Marinelli beaker, and the shape of source container. Results The gas components had little effect on the detection efficiency of the noble gas in the Marinelli beaker. The gas density had a relatively great effect on the detection efficiency of low-energy gamma ray. The Marinelli beaker of appropriate height and radius enabled the HPGe detector to get better measurement results. For the BE5030 HPGe detector, the highest detection efficiency of the Marinelli beakers of different volumes were observed at the location where the radius/height ratio was 0.7, and the optimal values of height and radius were given for the Marinelli beakers of different volumes. Conclusion Choosing Marinelli beaker of the appropriate size can improve the detection efficiency of noble gas in the effluent from nuclear power plants.
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Objective To explore the effeetiviness of the method of LabSOCS(Laboratory sourceless calibration software)efficiency calibration in laboratory rapid analysis for emergency monitoring of nuclear incidents.Methods The detection efficiency of three kinds of environmental samples in emergency monitoring Wag calculated bY using the LabSOCS efficiency calibration method,and compared with the values that were obtained by way of radioactive source calibration method.Results The maximum relative deviation of the detection efficiency between the two methods was less than 15%,and the values with relative deviation less than 5%accounted for 70%.Conclusions The LabSOCS efficiency calibration method might take the place of radioactive source efficiency calibration method,and meet the requirement of rapid analysis in emergency monitoring of the nuclear incidents.
RESUMEN
Objective To establish an efficiency calibration method without a radioactive source for Inspector 2000 gamma spectroscopy system.Methods At the fwst step,geometry parameters of the detector were properly specified by comparisons of FEPE(Full Energy Peak Efficiency)between Monte Carlo(MC)calculations and the average measured values of HPGe and NaI detectors using point sources(137 Cs).The differences between calculations and measurements were generally within ±10% for gamma rays.Then,Monte Carlo simulation was used to evaluate the counting efficiency of Nal(TI)and HPGe detectors for BOMAB phantoms.Corresponding efficiency curves and functions were fitted.Results The counting efficiency received from the fitted efficiency functions had a good agreement with those from MC simulation.The bias for Nal detector ranged from-19% to 18%,while the bias for HPGe detector ranged from-11% to 17%.The above errors were totally acceptable in the on-site deployment during nuclear and radiological emergency events.Conclusions Monte Carlo method is simple,time and laborsaving in determing the counting efficiency of gamma spectroscopy system.