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Buildup with Bremsstrahlung in the Martian Atmosphere
Nuclear Science and Engineering ( IF 1.2 ) Pub Date : 2020-09-08 , DOI: 10.1080/00295639.2020.1794455
Praneel P. Gulabrao 1 , Kevin T. Clarno 1
Affiliation  

Abstract Photon buildup is a function of energy, medium, and geometry and therefore must be specifically calculated for the case of interest. The Martian atmosphere, mostly comprising carbon dioxide, is becoming more relevant to radiation researchers and therefore warrants the study of this gas mixture’s buildup properties for ionizing photon flux resulting from the secondary effects of galactic cosmic rays and solar flares. Specifically, this work uses the MCNP6 code to develop energy absorption buildup factors in finite slab models for energies ranging from 40 keV to 15 MeV with Martian regolith as the backscattering medium. The Martian carbon dioxide cycle is accounted for by determining maximum and minimum mean densities as a function of orbital position. An isotropic point source model for the atmosphere is also developed using the geometric progression fitting function. Buildup is bounded to a factor of approximately 23 at 100 keV for normally incident photons at the top of the atmosphere. For conservatism, the design problem neglects coherent scattering but assumes bremsstrahlung effects and uses Klein-Nishina free-electron cross sections for Compton scattering.

中文翻译:

在火星大气中建立轫致辐射

摘要 光子累积是能量、介质和几何形状的函数,因此必须针对感兴趣的情况专门计算。火星大气,主要由二氧化碳组成,与辐射研究人员越来越相关,因此需要研究这种气体混合物的积累特性,用于电离光子通量,这是由银河宇宙射线和太阳耀斑的二次效应引起的。具体来说,这项工作使用 MCNP6 代码在有限板模型中开发能量吸收累积因子,能量范围从 40 keV 到 15 MeV,火星风化层作为背向散射介质。火星二氧化碳循环是通过确定最大和最小平均密度作为轨道位置的函数来解释的。还使用几何级数拟合函数开发了大气各向同性点源模型。对于大气顶部的正常入射光子,在 100 keV 时,累积的系数约为 23。为保守起见,设计问题忽略相干散射但假设轫致辐射效应并使用 Klein-Nishina 自由电子截面进行康普顿散射。
更新日期:2020-09-08
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