外推电离室关键参数测量方法的研究  

Study of measurement method for key parameters of extrapolation chamber

作　　者：杭仲斌 田丽霞[1] 宋明哲[2] 王红玉[2] 刘川凤 唐伟伟 HANG Zhongbin;TIAN Lixia;SONG Mingzhe;WANG Hongyu;LIU Chuanfeng;TANG Weiwei(East China University of Technology,Nanchang 330013,China;National Key Laboratory for Metrology and Calibration Techniques,China Institue of Atomic Energy,Beijing 102488,China)

机构地区：[1]东华理工大学,江西南昌330013 [2]中国原子能科学研究院计量校准与技术重点实验室,北京102488

出　　处：《中国测试》2021年第5期1-5,23,共6页China Measurement & Test

基　　金：国家自然科学基金项目(12075056)。

摘　　要：为实现外推电离室对β辐射吸收剂量的准确测量,按照外推电离室参数对性能的影响程度,对PTW23392型外推电离室进行漏电流、饱和曲线、离子收集效率、外推曲线和电离室零点位置与有效收集面积5大参数的测量。实验使用^(90)Sr/^(90)Y和^(85)Kr放射源(带展平过滤)进行测量和分析研究。极板间距取0.5 mm、1.0 mm、1.5 mm、2.0 mm、2.5 mm 5个位置,将极板间距外推至零,以求满足Bragg-Gray理论。实验得出结论:漏电流的范围为0.2~2.2 fA;由饱和曲线可知,当给外推电离室施加电压5 V、10 V、15 V、20 V、25 V时,外推电离室处于饱和区域;电离室离子收集效率均在99.3%以上;外推曲线的线性拟合度均在0.998以上。以上数据满足IEC-60731和IAEA TRS-398要求。通过电压阶跃法得出电离室的零点位置为0.0086 cm处,有效收集面积为7.2272 cm^(2)。因此,可确定此外推电离室满足β辐射吸收剂量测量的基本要求。In order to realize the accurate measurement of radiation absorbed dose in the extrapolation chamber,the leakage current,saturation curve,ion collection efficiency,extrapolation curve and zero point position and effective collection area of the PTW23392 extrapolation chamber were measured according to the degree of influence of the parameters of the extrapolation chamber on the performance.The^(90)Sr/^(90)Y and^(85)Kr radioactive sources(with flattening filter)were used for measurement and analysis.The chamber depth was taken as 0.5 mm,1.0 mm,1.5 mm,2.0 mm and 2.5 mm,and the chamber depth was extrapolated to zero,so as to meet the Bragg-Gray theory.The experiment concluded that the leakage current range was 0.2-2.2 fA.According to the saturation curve,when voltage 5 V,10 V,15 V,20 V and 25 V are applied to the extrapolation chamber,the extrapolation chamber is in the saturation region.The ion collection efficiency of ionization chamber is above 99.3%.The linear fitting degree of the extrapolation curves was above 0.998.The above data all meet the requirements of the IEC-60731 and IAEA TRS-398.The voltage step method was adopted to obtain the zero point position of extrapolation chamber as 0.0086 cm and the effective collection area as 7.2272 cm^(2).Therefore,it can be determined that the extrapolation chamber satisfies the basic requirements of radiation absorbed dose measurement.

关 键 词：外推电离室 Β射线 ^(90)Sr/^(90)Y ^(85)Kr 

分 类 号：TL84[核科学技术—核技术及应用] TL82