Townsend L W, Cucinotta F A
NASA Langley Research Center, Hampton, VA 23681-0001, USA.
Adv Space Res. 1996;17(2):59-68. doi: 10.1016/0273-1177(95)00513-e.
It has been known for some time that adequate assessment of spacecraft shield requirements and concomitant estimates of astronauts radiation exposures from galactic cosmic radiation requires accurate, quantitative methods for characterizing these radiation fields as they pass through thick absorbers. The main nuclear interaction processes involved are (1) nuclear elastic and inelastic collisions, and (2) nuclear breakup (fragmentation) and electromagnetic dissociation (EMD). Nuclear fragmentation and EMD are important because they alter the elemental and isotopic composition of the transported radiation fields. At present, there is no suitably accurate theory for predicting nuclear fragmentation cross sections for all collision pairs and energies of interest in space radiation protection. Typical cross-section differences between theory and experiment range from about 25 percent to a factor of two. The resulting errors in transported flux, for high linear energy transfer (LET) particles, are comparble to these cross-section errors. In this overview, theoretical models of heavy ion fragmentation currently used to generate input data bases for cosmic-ray transport and shielding codes are reviewed. Their shortcomings are discussed. Further actions needed to improve their accuracy and generality are presented.
一段时间以来，人们已经知道，要充分评估航天器屏蔽要求以及随之而来的对宇航员因银河宇宙辐射产生的辐射暴露的估计，需要准确的定量方法来表征这些辐射场穿过厚吸收体时的情况。所涉及的主要核相互作用过程有：（1）核弹性和非弹性碰撞，以及（2）核破裂（碎裂）和电磁离解（EMD）。核碎裂和EMD很重要，因为它们会改变传输辐射场的元素和同位素组成。目前，尚无适用于预测空间辐射防护中所有感兴趣的碰撞对和能量下的核碎裂截面的精确理论。理论与实验之间典型的截面差异范围从约25%到两倍不等。对于高线性能量转移（LET）粒子，由此产生的传输通量误差与这些截面误差相当。在本综述中，回顾了目前用于生成宇宙射线传输和屏蔽代码输入数据库的重离子碎裂理论模型。讨论了它们的缺点。提出了提高其准确性和通用性所需的进一步行动。
