载人深空探测被动屏蔽优化仿真研究
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摘要
深空环境下高能银河宇宙射线与防护材料间产生了复杂多样的次级粒子,使得航天员辐射损伤效应和防护问题突出。运用Geant4蒙特卡罗仿真工具,计算了1000 MeV·n~(-1)的铁离子与铝或聚乙烯相互作用后,产生次级碎片粒子分布规律;分析了银河宇宙射线经过不同材料屏蔽体后,其碎片及次级中子对人体剂量当量的贡献随屏蔽厚度变化规律;依据该规律优化设计质量密度为20 g/cm~2聚乙烯掺杂比为15%硼的复合材料,得到的仿真设计复合材料成分比例可为载人航天被动屏蔽材料制备提供依据。
Complex nuclear reactions will occur between the high-energy galactic cosmic rays and the protective materials in deep space environment and a large number of secondary particles will be produced which makes the astronaut dose protection very complex. Based on the Monte-Carlo simulation software Geant4, the distribution law of the secondary debris particles generated after the interaction between 1000 MeV·n~(-1) Fe ion and the shielding material aluminum or polyethylene was studied. The changes of the debris and the secondary neutrons with the shielding thickness for the galactic cosmic ray radiation particles were analyzed. Based on those researches, the composite material with a mass density of 20 g/cm~2 and polyethylene doped ratio of 15% boron was optimized. The obtained proportion of the simulated composite material may provide the basis for the preparation of passive shielding materials in manned spaceflight.
Complex nuclear reactions will occur between the high-energy galactic cosmic rays and the protective materials in deep space environment and a large number of secondary particles will be produced which makes the astronaut dose protection very complex. Based on the Monte-Carlo simulation software Geant4, the distribution law of the secondary debris particles generated after the interaction between 1000 MeV·n~(-1) Fe ion and the shielding material aluminum or polyethylene was studied. The changes of the debris and the secondary neutrons with the shielding thickness for the galactic cosmic ray radiation particles were analyzed. Based on those researches, the composite material with a mass density of 20 g/cm~2 and polyethylene doped ratio of 15% boron was optimized. The obtained proportion of the simulated composite material may provide the basis for the preparation of passive shielding materials in manned spaceflight.
引文
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[12] Geant4 Team. Geant4 physics reference manual[EB/OL]. (2015)[2018].http://geant4.web.cern.ch/geant4/support/user documents.shtml.
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[2] Durante M, Cucinotta F. Physical basis of radiation protection in space travel[J]. Reviews of Modern Physics,2011, 83(4):1245-1281.
[3] 方美华, 魏志勇,杨浩,等. 高能铁离子在水介质中核反应过程所导致的能量沉积[J]. 物理学报,2008, 57(10):6196-6201.Fang M H, Wei Z Y, Yang H, et al. The energy deposit of high energy Fe ions inject in water due to nuclear reaction[J].Acta Physica Sinica,2008, 57(10):6196-6201.(in Chinese)
[4] Durante M. Space radiation protection: destination Mars[J]. Life Sciences in Space Research, 2014, 1: 2-9.
[5] Francis A C, Robert K, John W W, et al. Heavy ion track-structure calculations for radial dose in arbitrary materials[R]. NASA Technical,1995: 3497.
[6] Cucinotta F A, Myung-Hee M K, Lei R. Managing Lunar and Mars mission radiation risks part I: cancer risks, uncertainties, and cancer shielding effectiveness[R]. NASA TP-2005-213164, 2005:1-44
[7] 荀明珠,何承发, 陆妩,等.高能56Fe离子入射屏蔽材料的次级粒子模拟分析[J].核技术,2016,39(06):060201.Xun M Z,He C F,Lu F,et al. Secondary particle simulation analysis of high-energy 56Fe ion inject various shielding material[J]. Nuclear Techniques, 2016,39(06):060201. (in Chinese).
[8] Agostinelli S,Allison J, Amako K,et al. GEANT4-a simulation toolkit[J]. Nuclear Instruments and Methods in Physics Research Section A,2003,506(3):250-303.
[9] Wilson J W, Tripathi R K, Cucinotta F A, et al. An evaluation of the semiempirical nuclear fragmentation database[R]. NASA Technical paper 3553,1995.
[10] Townsend L W, Wilson J W, Tripathi R K, et al. An energy-dependent semiempirical nuclear fragmentation model[R]. NASA HZEFRG1 Technical Paper 3310,1993:1-20.
[11] Cucinotta F A. Multiple-scattering model for inclusive proton production in heavy ion collision[R]. NASA Technical Paper 3470,1994.
[12] Geant4 Team. Geant4 physics reference manual[EB/OL]. (2015)[2018].http://geant4.web.cern.ch/geant4/support/user documents.shtml.
[13] ICRP. Assessment of radiation exposure of astronauts in space. ICRP Publication 123[J]. Ann. ICRP, 2013, 42(4): 1-339.