球形石墨空腔电离室壁修正因子的测量与验证  

Measurement and verification of wall correction factor for the spherical graphite cavity chamber

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

机构地区：[1]北京中国计量科学研究院,100013 [2]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

出　　处：《中华放射医学与防护杂志》2005年第6期561-564,共4页Chinese Journal of Radiological Medicine and Protection

基　　金：国家自然科学基金资助项目(10275058)

摘　　要：Objective To discuss the method how to identify wall correction factor (K_ wall ). Methods The paper introduce how to use extrapolation of the ionization current measured for different wall thickness by the spherical graphite cavity chamber whose volume is 10 cm3 and 30 cm3 for 60 Co γ-rays. The wall correction factors were determined by this method and Monte Carlo(MC) calculations. Results The results of the present experiment and calculation indicated that the wall correction factor determined by traditional geometry thickness extrapolation method was 1.0% less than that by MC calculation.The result of applying the equivalent mean thickness to calculate with extrapolation method and that of MC calculation were accordable within 0.45%.The relative dose and wall correction factors for the spherical graphite cavity chamber whose volume is 30 cm3 and 50 cm3 of the standards of air kerma of the NIST for 60 Co γ-rays were calculated by MC calculation,and the calculation results were in accordance with the published values of NIST within 0.06%. Conclusion The spherical graphite cavity chamber wall correction factor determined by traditional extrapolation method and MC calculation is accordable with the results of foreign labs (PSDL).;Objective To discuss the method how to identify wall correction factor （ Kwall ） . Methods The paper introduce how to use extrapolation of the ionization current measured for different wall thickness by the spherical graphite cavity chamber whose volume is 10 cm^3 and 30 cm^3 for ^6o Co γ-rays. The wall correction factors were determined by this method and Monte Carlo （MC） calculations. Results The results of the present experiment and calculation indicated that the wall correction factor determined by traditional geometry thickness extrapolation method was 1.0% less than that by MC calculation, The result of applying the equivalent mean thickness to calculate with extrapolation method and that of MC calculation were accordable within 0.45 % , The relative dose and wall correction factors for the spherical graphite cavity chamber whose volume is 30 cm^3 and 50 cm^3 of the standards of air kerma of the NIST for ^6o Co γ-rays were calculated by MC calculation, and the calculation results were in accordance with the published values of NIST within 0.06%. Conclusion The spherical graphite cavity chamber wall correction factor determined by traditional extrapolation method and MC calculation is accordable with the results of foreign labs （PSDL） .

关 键 词：空腔电离室 空气比释动能 壁修正因子Kwall 蒙特卡罗模拟 

分 类 号：TL811.1[核科学技术—核技术及应用]