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"。
ObjectiveTo explore the causes of the crosstalk in the grossαand grossβmeasurement using an MPC 9604 low backgroundα/βcounter.MethodsWith 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 grossαand grossβexperiments,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 grossαand grossβmeasurement with an MPC 9604 low backgroundα/βcounter.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 theβchannel of the low backgroundα/βcounter.The same test with the shielding material of two layers of PE films showed that theαcount rate further decreased by about 36.5%,while theβcount rate hardly changed.The grossαand grossβexperiments andγspectrometry with the shielding material of stainless steel demonstrated that the characteristicγray peaking at 59.5 keV of the 241Am powder source did not generate one count in theβchannel.40K powder source experimental result:when the source was covered with steel of total thickness of 0.965 mm in the grossαand grossβexperiments,theγrays of 40K did not generate one count in theβchannel.Compared with naked 40K powder source,when source was covered with one and two sheets of copy paper,the grossαcount 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 otherαnuclides in 40K powder source.ConclusionsTheβcounting in theβchannel with the 241Am powder source using MPC 9604 low backgroundα/βcounter was,instead ofα-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
作者
许家昂
宋钢
李海亮
吴芳芳
金畅
闵楠
王小山
Xu Jiaang;Song Gang;Li Hailiang;Wu Fangfang;Jin Chang;Min Nan;Wang Xiaoshan(School of Preventive Medicine Sciences(Institute of Radiation Medicine),Shandong First Medical University(Shandong Academy of Medical Sciences),Jinan 250118,China)
出处
《中华放射医学与防护杂志》
CAS
CSCD
北大核心
2024年第11期965-970,共6页
Chinese Journal of Radiological Medicine and Protection
