Affiliation:
1. National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention, Key Laboratory of Radiological Protection and Nuclear Emergency, No.2 Xinkang Street, Deshengmenwai, Beijing 100088, China.
Abstract
Abstract
In the absolute measurement method of nuclide radioactivity by the internal gas proportional counter, the reasonable correction of the small pulse counting loss is the key to obtaining the measurement results accurately. Considering the decay type and energy of radioactive gas nuclides, the influence of the low-energy beta particles and the wall effect counting loss on the activity measurement results is different also. To this end, two typical radioactive gas nuclides (37Ar and 3H) are used to study the cause of counting loss based on the Monte Carlo simulation. The results show that the counting loss of small pulse in the activity measurement of 37Ar comes mainly from the wall effect generated by x rays. Within the given gas pressure of 60-300 kPa, the simulated wall effect correction factors are 1.063-1.021. The decay energy of β particles generated by 3H is very low, and there is no obvious wall effect. The small pulse counting loss mainly comes from the low-energy beta particles’ contribution with the energy below the counting threshold, which can be corrected by extrapolating the beta energy spectrum at a lower counting threshold (below 1 keV).
Publisher
Ovid Technologies (Wolters Kluwer Health)
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