Astronauts are exposed to ionizing radiation that may pose significant health risks from missions to low Earth orbit (LEO) and beyond. The National Aeronautics and Space Administration (NASA) uses the deterministic radiation transport code, High charge (Z) and Energy TRaNsport (HZETRN), to estimate particle fluxes inside shielded vehicles to evaluate risk of radiation exposure to crew members. Highly efficient radiation transport algorithms and cross section models are needed to perform calculations in realistic vehicles with complex geometrical configurations. The HZETRN code uses the NUClear FRaGmentation (NUCFRG) model to evaluate fragmentation cross section products from nucleus–nucleus collisions. Although highly efficient, the NUCFRG model has some limitations that are based on its unique implementation of the abrasion–ablation formalism. NUCFRG performs well in predicting fragmentation cross sections on the average when compared to experimental data; however, even–odd nuclear structure effects observed in laboratory measurements are absent. The aim of the present work is to formulate a self-consistent theory that produces accurate nuclear fragmentation cross sections while maintaining numerical efficiency. To that end, the Relativistic Abrasion–Ablation FRaGmentation (RAADFRG) model has been developed. The theoretical framework for nuclear interaction is multiple scattering theory (MST), where relativistic kinematics may be included in the momentum–space representation of the Lippmann–Schwinger equation. The nuclear abrasion model employs the Eikonal (Eik) approximation and is used to predict prefragment cross sections. A novel approach is utilized for the excitation energy of prefragment, where in addition to differences of binding energies between two nuclei, energy is transferred to the prefragment from subsequent multiple scattering of abraded nucleons with the spectator nucleon constituents of the prefragment. Next, the excited prefragment liberates particles through the nuclear ablation process, and a nuclear coalescence model that forms aggregate particles for each prefragment channel is included in the yield. The ElectroMagnetic Dissociation FRaGmentation (EMDFRG) model is also included for peripheral interactions that stimulates particle emission via nuclear-photon field interactions. When compared to NUCFRG3, uncertainty quantification analysis shows that RAADFRG is better able to predict experimental nuclear fragmentation cross sections. RAADFRG is also shown to produce the even–odd nuclear structure effects, which is achieved by modification of isospin pairing correction in the prefragment excitation energy model.

宇航员暴露于电离辐射中，这可能会对低地球轨道 (LEO) 及更远的任务造成重大健康风险。美国国家航空航天局 (NASA) 使用确定性辐射传输代码、高电荷 (Z) 和能量传输 (HZETRN) 来估计屏蔽车辆内的粒子通量，以评估机组人员受到辐射的风险。需要高效的辐射传输算法和横截面模型来在具有复杂几何配置的现实车辆中执行计算。HZETRN 代码使用 NUClear FRaGmentation (NUCFRG) 模型来评估核-核碰撞产生的碎片横截面产物。虽然效率很高，但 NUCFRG 模型有一些局限性，这是基于其对磨损-消融形式主义的独特实现。与实验数据相比，NUCFRG 在平均预测碎片横截面方面表现良好；然而，在实验室测量中观察到的奇偶核结构效应不存在。目前工作的目的是制定一个自洽理论，在保持数值效率的同时产生准确的核碎片横截面。为此，开发了相对论磨损-消融 FRaGmentation (RAADFRG) 模型。核相互作用的理论框架是多重散射理论 (MST)，其中相对论运动学可能包含在 Lippmann-Schwinger 方程的动量空间表示中。核磨损模型采用 Eikonal (Eik) 近似，用于预测预断片断面。一种新的方法用于前碎片的激发能量，其中除了两个核之间结合能的差异之外，能量从随后的磨损核子与前碎片的观察核子成分的多次散射转移到前碎片。接下来，被激发的预片段通过核消融过程释放粒子，并且为每个预片段通道形成聚集粒子的核聚结模型包含在产量中。电磁解离 FRaGmentation (EMDFRG) 模型也包括在外围相互作用中，通过核光子场相互作用刺激粒子发射。与 NUCFRG3 相比，不确定性量化分析表明 RAADFRG 能够更好地预测实验核碎片横截面。