The calibration of transfer standards for the measurement of 222Rn at NIM

Changhao Sun; Zihao Fan; Zhijie Yang; Meiling Liu; Juncheng Liang; Haoran Liu; Jian Zhang; Xiangping Qiu

doi:10.1016/j.apradiso.2023.110971

The calibration of transfer standards for the measurement of ²²²Rn at NIM

Appl Radiat Isot. 2023 Oct:200:110971. doi: 10.1016/j.apradiso.2023.110971. Epub 2023 Aug 2.

Authors

Changhao Sun¹, Zihao Fan², Zhijie Yang¹, Meiling Liu¹, Juncheng Liang³, Haoran Liu¹, Jian Zhang¹, Xiangping Qiu¹

Affiliations

¹ Division of Ionizing Radiation Metrology, National Institute of Metrology, Beijing, 100029, China.
² Division of Ionizing Radiation Metrology, National Institute of Metrology, Beijing, 100029, China; China Institute of Atomic Energy, Beijing, 102413, China.
³ Division of Ionizing Radiation Metrology, National Institute of Metrology, Beijing, 100029, China. Electronic address: liangjc@nim.ac.cn.

PMID: 37611497
DOI: 10.1016/j.apradiso.2023.110971

Abstract

A high-purity germanium (HPGe) gamma-ray spectrometer and an Alpha-GUARD radon monitor are the activity and activity concentration transfer standards of ²²²Rn, respectively. The gaseous ²²²Rn standard source traceable to the NIM's absolute standardization apparatus of ²²²Rn was developed for calibrating these transfer standards. The calibration results of HPGe detector at three different distances show that the uncertainties of experimental efficiency are less than 0.77% (k = 1). Meanwhile, the Monte Carlo (MC) simulation was carried out at wider distances range for the HPGe calibration as well, and the deviation at same three distances between experiments and simulations results is within ±3.0%. The advantage of calibration using MC simulation and the possible reasons for the deviation were discussed in detail in this article. In addition, a reference activity concentration environment based on the gaseous ²²²Rn standard source was also developed to calibrate the radon monitor, and the typical uncertainty for calibration factor of Alpha-GUARD radon monitor could be reduced to 1.9% (k = 1).

Keywords: Calibration; Gaseous (222)Rn standard source; Radon; Transfer standard.