球形石墨空腔电离室壁修正因子的Monte-Carlo模拟和实验测量  

Monte-Carlo Calculation and Measurement of Wall Correction Factor for Spherical Graphite Ionization Chamber

作　　者：刘鉴常[1] 孙吉宁[1] 杨小元[2] 郭彬[2] 叶卫国[1] 黄斐增[1] 杨元第[2] 胡家成[2] 樊铁栓[1] 

机构地区：[1]北京大学物理学院重离子物理研究所重离子物理教育部重点实验室,北京100871 [2]中国计量科学研究院电离辐射与医学处,北京100013

出　　处：《原子能科学技术》2006年第6期723-728,共6页Atomic Energy Science and Technology

基　　金：国家自然科学基金(10275058)

摘　　要：采用Monte-Carlo模拟和实验测量两种方法对30 cm^3和10cm^3球形石墨空腔电离室在^(?)Coγ射线下的壁修正因子K_(wall)进行研究。实验和模拟计算结果的比较表明,传统的线性外推法确定的壁修正因子比Monte-Carlo模拟计算结果约偏低1．0％。对美国国家标准技术研究所(NIST)国家空气比释动能基准组的30 cm^3和50 cm^3球彤石墨空腔电离室在^(60)Coγ射线下的相对电离电流和壁修正因子进行了Monte-Carlo模拟计算,计算的相对电离电流值与NIST发布的实验测量值在0．12％内吻合。The factor Kwall to correct for photon attenuation and scalier in the wall of the 30 cm^3 and 10 cm^3 spherical chambers at National Institute of Metrology for ^60Co airkerma measurement is determined by Monte-Carlo calculation and experimental measurement. The calculation using the EGSnrc software system shows that the calculated wall correction factors differ by up to 1.0% from those obtained by linear extrapolations of the measured relative ionization current to zero wall thickness for the measured chambers, The relative ionization eurrenl and wall correction factors for the 30 cm^3 and 50 cm^3 spherical graphite chambers at NIST are calculated and compared with the measured results. The current within an Monte-Carlo code can reproduce the experimental accuracy of ±0.12%. This work confirms that for relative ionization spherical standard chambers the ^60Co air-kerma reference values should be obtained by a new Kwall determined by Monte-Carlo calculations.

关 键 词：石墨电离室 空气比释动能 壁修正因子 MONTE-CARLO模拟 

分 类 号：TL818[核科学技术—核技术及应用]