Preliminary testing and analysis of crosstalk in gross α and gross β measurement using an MPC 9604 low background α/β counter
10.3760/cma.j.cn112271-20231205-00198
- VernacularTitle:MPC 9604型低本底α、β计数器总α和总β测量串道的初步测试与分析
- Author:
Jiaang XU
1
;
Gang SONG
;
Hailiang LI
;
Fangfang WU
;
Chang JIN
;
Nan MIN
;
Xiaoshan WANG
Author Information
1. 山东第一医科大学（山东省医学科学院）预防医学科学学院（放射医学研究所），济南 250118
- Keywords:
MPC 9604;
Gross α;
Gross β;
Crosstalk
- From:
Chinese Journal of Radiological Medicine and Protection
2024;44(11):965-970
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To explore the causes of the crosstalk in the gross α and gross β measurement using an MPC 9604 low background α/β counter.Methods:With the A4 copy paper (70 g/m 2), polyethylene (PE) films (8.7 g/m 2), and 304 stainless steel seperately as shielding materials, the gross α and gross β experiments, gamma spectrometry experiments and solid state nuclear track detection (SSNTD) experiments were conducted by using 241Am and 40K standard materials. A comprehensive analysis encompassing statistical analysis and nuclear physics analysis was performed to reveal the impact of contributing factors on the crosstalk in the gross α and gross β measurement with an MPC 9604 low background α/β counter. Results:241Am powder source experimental result: when two sheets of copy paper were used in the experiment, α-rays did not generate one count in the β channel of the low background α/β counter. The same test with the shielding material of two layers of PE films showed that the α count rate further decreased by about 36.5%, while the β count rate hardly changed. The gross α and gross β experiments and γ spectrometry with the shielding material of stainless steel demonstrated that the characteristic γ ray peaking at 59.5 keV of the 241Am powder source did not generate one count in the β channel. 40K powder source experimental result: when the source was covered with steel of total thickness of 0.965 mm in the gross α and gross β experiments, the γ rays of 40K did not generate one count in the β channel. Compared with naked 40K powder source, when source was covered with one and two sheets of copy paper, the gross α count rate decreased approximately from 3.30 × 10 -3 to 1.50 × 10 -3 and 1.75 × 10 -3, respectively. The SSNTD indicated the presence of other α nuclides in 40K powder source. Conclusions:The β counting in the β channel with the 241Am powder source using MPC 9604 low background α/β counter was, instead of α-rays, caused by the internal conversion electrons and the characteristic X rays of 11.870-22.402 keV emitted from the 241Am powder source, thus this is not a true α/β crosstalk. The α counting in α channel with the 40K powder source, except the contribution of impurity α nuclides, was mainly attributed to the α signals arising from β particles when the amplitude of the piled-up β pules exceeded the discrimination threshold of the detector, therefore it is a true crosstalk.
