| 许家昂,宋钢,李海亮,等.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[J].中华放射医学与防护杂志,2024,44(11):965-970.Xu Jiaang,Song Gang,Li Hailiang,et al.Preliminary testing and analysis of crosstalk in gross α and gross β measurement using an MPC 9604 low background α/β counter[J].Chin J Radiol Med Prot,2024,44(11):965-970 |
| 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 |
| Preliminary testing and analysis of crosstalk in gross α and gross β measurement using an MPC 9604 low background α/β counter |
| 投稿时间：2023-12-05 |
| DOI：10.3760/cma.j.cn112271-20231205-00198 |
| 中文关键词: MPC 9604 总α 总β 串道 |
| 英文关键词:MPC 9604 Gross α Gross β Crosstalk |
| 基金项目: |
|
| 摘要点击次数: 1190 |
| 全文下载次数: 451 |
| 中文摘要: |
| 目的 探索MPC 9604型低本底α、β计数器总α与总β测量串道产生的原因。方法 采用241Am和40K标准物质,以A4复印纸(70 g/m2)、聚乙烯(PE)膜(8.7 g/m2)和304不锈钢等为屏蔽材料,进行总α和总β测试、γ能谱测试和固体核径迹测试,使用原子核物理学方法分析MPC 9604型低本底α、β计数器总α与总β测量串道的影响因素。结果 241Am粉末源实验结果显示,2张复印纸屏蔽测试发现α射线不在低本底α、β计数器β道产生计数,进一步用PE膜屏蔽测试表明,2层比1层PE膜的α道净计数率降低约36.5%,而β道净计数率未再降低。304不锈钢屏蔽条件下总α和总β测试和γ能谱测试发现,241Am 59.5 keV特征γ射线不在β道产生计数。40K粉末源实验结果中,用厚0.965 mm 304不锈钢屏蔽条件下总α和总β测试,发现40K产生的γ射线在β道没有产生计数;用1和2张复印纸屏蔽进行总α和总β测试,发现α道计数率占总计数率的比值由未屏蔽时的3.30×10-3分别降至1.50×10-3和1.75×10-3;进一步对40K粉末源进行固体核径迹测试发现,40K粉末源含有杂质α核素。结论 MPC 9604型低本底α、β计数器测量241Am粉末源在β道产生的计数不是由241Am源衰变α射线产生的,而是由241Am源内转换电子和11.870~22.402 keV特征X射线造成的,不是真正意义上的“串道”。测量40K粉末源在α道“串道”产生的计数,除杂质α核素影响外,主要是多个电子在探测器产生β脉冲堆积超过α甄别阈而被记录为α信号,存在真正意义上的“串道”。 |
| 英文摘要: |
| 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/m2), polyethylene (PE) films (8.7 g/m2), 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. |
| HTML 查看全文 查看/发表评论 下载PDF阅读器 |
| 关闭 |
|
|
|