非均整条件下β射线组织吸收剂量率测量技术研究  

Research on Measurement of β Ray Absorbed Dose Rate under Nonuniform Conditions

作　　者：董世彬 魏可新[1] 宋明哲[1] 滕忠斌 刘川凤 王红玉[1] DONG Shi-bin;WEI Ke-xin;SONG Ming-zhe;TENG Zhong-bin;LIU Chuan-feng;WANG Hong-yu(National Key Laboratory for Metrology and Calibration Techniques,China Institute of Atomic Energy,Beijing 102413,China)

机构地区：[1]中国原子能科学研究院,计量与校准技术重点实验室,北京102413

出　　处：《宇航计测技术》2021年第5期67-74,共8页Journal of Astronautic Metrology and Measurement

摘　　要：基于^(90)Sr-^(90)Y和^(85)Kr放射源产生的β射线参考辐射场,对非均整条件下β射线参考辐射场中组织吸收剂量率进行了绝对测量。采用电容法测量得到外推电离室的有效收集面积为7.25cm^(2)。该有效收集面积与几何标称值的相对偏差为0.185cm^(2)。通过实验测量了收集体积中的空气密度修正因子k_(ad)、轫致辐射影响修正因子k_(br)和复合损失修正因子k_(sat)。并使用蒙特卡罗方法计算了外推电离室侧壁对β粒子通量密度扰动的修正因子k_(pe)和在收集体积中吸收剂量率不均匀性的修正因子k_(ih)。通过测量和模拟与外推电离室相关参数及修正因子,确定了放射源常用校准距离(放射源距电离室入射窗11cm,20cm,30cm和50cm)处的组织吸收剂量率,扩展不确定度分别为2.7%(k=2)和2.9%(k=2)。本研究结果可以为完善β射线剂量当量溯源及量值传递提供技术保障。According to the β-ray reference radiation fields generated by ^(90)Sr-^(90)Y and ^(85)Kr sources,the measurement of tissue absorbed dose rate under non-uniform conditions.The effective collection area of 7.25 cm^(2) was measured with the capacitance method.The relative deviation of the effective collection area from the geometric nominal value is 0.185 cm^(2).And then the correction factors were measured,including the correction factor for the variations in the attenuation and scattering of beta particles between the source and the collecting volume due to variations from reference conditions,k_(abs),the correction factor for the variations of air density in the collecting volume from reference conditions,k_(ad),the correction factor for the effect of bremsstrahlung from the beta-particle source,k_(br) and the correction factor for ionization collection losses due to ionic recombination,k_(sat).In conclusion,the characteristic parameters of the extrapolation chamber and several correction factors for absolute measurement of the absorbed dose rate were obtained in this work.And the absorbed dose rates at different calibration distances(11 cm,20 cm,30 cm and 50 cm from the radiation source to the entrance window of the chamber)were determined.The uncertainties of tissue absorption rate measurement for ^(90)Sr-^(90)Y and ^(85)Kr sources are 2.7%(k=2)and 2.9%(k=2),respectively.The results can provide technical supports for improving the traceability and the dissemination of the β-ray dose equivalent.

关 键 词：非均整条件 外推电离室 Β射线 吸收剂量 蒙特卡罗 

分 类 号：TL72[核科学技术—辐射防护及环境保护]