不同材料对空间辐射屏蔽特性的蒙特卡罗模拟研究

发布时间：2018-02-09 12:13

本文关键词： 空间辐射 Geant4 次级粒子屏蔽材料高能重离子　出处：《新疆大学》2016年硕士论文　论文类型：学位论文

【摘要】：空间辐射主要由银河宇宙辐射、太阳粒子事件和范艾伦地球辐射带组成。空间辐射环境中的质子、电子、高能重粒子等射线共同作用在航天器上,会对航天器内的宇航员和电子器件系统造成严重的影响。当宇航员长时间工作在空间辐射环境或进行太空行走工作时,射线穿过人体组织与组织细胞发生相互作用而传递能量时,将会诱导基因突变,对人体造成不可修复的严重损伤。GEANT4是欧洲核子中心(CERN)开发的一个用于模拟粒子在物质中输运过程的工具包,可以用来模拟各种常见的粒子与物质的相互作用,是一种常用的功能强大的蒙卡程序。在此我们根据需要,选择合适的相互作用过程和物理模型,并构建不同几何形状的屏蔽层,以达到最佳的仿真效果空间辐射环境。对各种粒子和射线在不同屏蔽体中的输运过程进行模拟,并计算屏蔽体后吸收体模型内的能量沉积、深度剂量分布、入射的初级次级粒子类型及能谱等。得到航天员在空间辐射下屏蔽后太空舱内的辐射环境,为进一步分析太空舱中宇航员及电子器件的吸收剂量提供模拟数据,为保障航天员在轨飞行的人身安全提供数据支持。本文使用基于蒙特卡罗方法的GEANT4软件模拟空间高能1GeV/n~(56)Fe离子入射质量厚度为1.35g/cm~2的铝、聚乙烯、碳和水四种屏蔽材料,分析透射屏蔽体的初级粒子及由屏蔽材料产生的次级电子、次级中子、次级质子和次级γ的能谱,屏蔽体产生的次级粒子入射水吸收体中的能量沉积及其深度剂量分布。分析产生的次级重粒子类型和能量,比较四种屏蔽材料对高能~(56)Fe离子的屏蔽性能。结果发现:1:对于空间高能1GeV/n ~(56)Fe离子入射质量厚度为1.35g/cm~2的铝、聚乙烯、碳和水四种屏蔽材料,聚乙烯材料的对高能Fe粒子的阻止本领最强,吸收能量最多为2.16×10~7MeV,初级粒子穿过屏蔽材料的能量最小,其次是液态水屏蔽效果较好,对高能Fe粒子屏蔽效果最差的为铝材料,仅吸收能量1.67×10~7MeV。2:由屏蔽材料产生的次级粒子中,次级中子和次级质子的能谱范围较广,能量较大,次级电子和次级γ射线的能谱相似,主要能量集中在0.1MeV处和30keV处。3:对于次级粒子在水吸收体中的能量沉积,次级电子和次级γ射线主要将能量沉积在吸收体表面,而次级中子和次级质子能够到达吸收体内部,沉积能量随吸收体深度的变化较缓。4:对于质量厚度为1.35g/cm~2的铝、聚乙烯、碳和水四种屏蔽材料,产生的次级重荷主要为靠近Fe原子序数在22到26之间的次级重核。原子序数在3到10之间的次级粒子产生较少。
[Abstract]:Space radiation is mainly composed of galactic cosmic radiation, solar particle events and Van Allen Earth radiation belt. The protons, electrons, high-energy heavy particles and other rays in the space radiation environment act together on the spacecraft. Can have a serious impact on astronauts and electronic device systems in spacecraft. When astronauts work long hours in a space radiation environment or perform spacewalk work, When radiation passes through the body's tissues and cells and transfers energy through it, it induces gene mutations. Severe irreparable damage to the human body. GEANT4 is a toolkit developed by the European Nuclear Center (CERN) to simulate the transport of particles in matter, which can be used to simulate the interaction of a variety of common particles with matter. Is a common powerful Monka program. Here we choose the appropriate interaction processes and physical models, and construct different geometric shielding layers. In order to achieve the best simulation effect, the transport process of various particles and rays in different shielding bodies is simulated, and the energy deposition and depth dose distribution in the model of absorber behind the shield are calculated. The radiation environment of the capsule after the astronauts are shielded under space radiation is obtained, which provides simulation data for further analysis of the absorbed doses of astronauts and electronic devices in the capsule. In order to provide data support for the safety of astronauts in orbit flight, this paper uses GEANT4 software based on Monte Carlo method to simulate four shielding materials, aluminum, polyethylene, carbon and water, with incident mass thickness of 1.35 g / cm ~ (2) for high energy 1 GeV / N ~ (-1) N ~ (-1) N ~ (-1) N ~ (-1) C ~ (-1) Fe ion in space. Analyzing the primary particles of the transmission shield and the energy spectra of secondary electrons, secondary neutrons, secondary protons and secondary 纬 produced by the shielding materials, Energy deposition and depth dose distribution in secondary particles incident into water absorbers produced by shield. Type and energy of secondary heavy particles, The shielding properties of four kinds of shielding materials for high energy ~ (56) Fe ions are compared. The results show that: 1: 1: for aluminum, polyethylene, carbon and water four shielding materials with incident mass thickness of 1.35 g / cm ~ (2) for high energy 1 GeV / n / n ~ (-1) ~ (-1) GE ~ (-1) N ~ (-1) O ~ (-1) Fe ions, The PE material has the strongest blocking power to the high-energy Fe particles, the absorption energy is 2.16 脳 10 ~ (7) MeV at most, the primary particles have the lowest energy through the shielding materials, the liquid water shielding effect is better, and the aluminum material has the worst shielding effect on the high-energy Fe particles. The absorbed energy is only 1.67 脳 10 ~ (7) MeV. 2: among the secondary particles produced by shielding materials, the energy spectrum of secondary neutron and secondary proton is larger and the energy of secondary neutron and secondary proton is larger, and the energy spectrum of secondary electron and 纬 -ray is similar. The main energy is concentrated at 0.1MeV and 30keV. 3: for the energy deposition of secondary particles in water absorbers, secondary electrons and secondary gamma rays mainly deposit energy on the surface of the absorbers, while secondary neutrons and secondary protons reach the absorbing body. The deposition energy varies slowly with the depth of the absorber. 4: for aluminum, polyethylene, carbon and water shielding materials with a mass thickness of 1.35 g / cm ~ (-2), The secondary heavy loads are mainly secondary heavy nuclei close to the atomic number of Fe between 22 and 26, and the secondary particles with atomic number between 3 and 10 produce less.
【学位授予单位】：新疆大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：V445.16;V520.6

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