Seltzer Stephen M, Bergstrom Paul M
National Institute of Standards and Technology, Gaithersburg, MD 20899.
J Res Natl Inst Stand Technol. 2003 Oct 1;108(5):359-81. doi: 10.6028/jres.108.031. Print 2003 Sep-Oct.
Monte Carlo photon-electron transport calculations have been done to derive new wall corrections for the six NBS-NIST standard graphite-wall, air-ionization cavity chambers that serve as the U.S. national primary standard for air kerma (and exposure) for gamma rays from (60)Co, (137)Cs, and (192)Ir sources. The data developed for and from these calculations have also been used to refine a number of other factors affecting the standards. The largest changes are due to the new wall corrections, and the total changes are +0.87 % to +1.11 % (depending on the chamber) for (60)Co beams, +0.64 % to +1.07 % (depending on the chamber) for (137)Cs beams, and -0.06 % for the single chamber used in the measurement of the standardized (192)Ir source. The primary standards for air kerma will be adjusted in the near future to reflect the changes in factors described in this work.
已进行蒙特卡罗光子 - 电子输运计算，以推导用于六个NBS - NIST标准石墨壁空气电离腔室的新壁修正值，这些腔室用作美国国家空气比释动能（及照射量）的初级标准，用于测量来自钴 - 60、铯 - 137和铱 - 192源的伽马射线。从这些计算中得出的数据也已用于完善一些影响标准的其他因素。最大的变化归因于新的壁修正值，对于钴 - 60射线束，总变化为 +0.87%至 +1.11%（取决于腔室），对于铯 - 137射线束，总变化为 +0.64%至 +1.07%（取决于腔室），而用于测量标准化铱 - 192源的单个腔室的变化为 -0.06%。空气比释动能的初级标准将在不久的将来进行调整，以反映本工作中所述因素的变化。
