串列加速器头部电极改进方案

通过改变头部电极的局部形状来改善头部电场, 运用Poisson程序计算几种可能形状下表面电场的分布, 并以此给出最佳的改进方案.     

质子入射散裂产物理论研究方法探讨

简要介绍了几种关于中高能质子入射引起散裂反应产物理论计算的方法,以及这些方法的最新发展.比较了这些方法在理论计算中的特点,指出经典外推方法有局限性,量子分子动力学方法和改进后的M C方法的计算结果与实验数据有较好的符合,但是计算量大,而且量子分子动力学方法在与宏观输运理论连接上存在不少的困难.半经验计算方法已经取得了初步的成果,需要根据新的实验结果来对其进行发展. The analysis on spallation product of proton-induced reaction with intermediate energy has important applications, such as astrophysics, biophysics, spallation neutron source, and accelerator-driven system (ADS) etc. In recent year, some theoretical models have been developed to investigate this reaction processes. At present work, we introduce the extrapolated classic theory, the quantum molecule dynamic (QMD) plus statistical decay and fission models, the method of Mento-Carlo and Smiempirical method for...     

低能质子在半导体材料Si 和GaAs中的非电离能损研究

非电离能损(NIEL)引起的位移损伤是导致空间辐射环境中新型光电器件失效的主要因素.由于低能时库仑相互作用占主导地位,一般采用Mott-Rutherford微分散射截面,但它没考虑核外电子库仑屏蔽的影响.为此,本文采用解析法和基于Monte-Carlo方法的SRIM程序计算了考虑库仑屏蔽效应后低能质子在半导体材料Si,GaAs中的NIEL,SRIM程序在计算过程中采用薄靶近似法, 并与其他作者的计算数据和实验数据进行了比较.结果表明：用SRIM程序计算NIEL时采用薄靶近似法处理是比较合理的,同时考虑库仑 关键词： 低能质子 非电离能损 硅 砷化镓     

论FeCr合金辐照损伤的多尺度模拟

铁素体/马氏体钢具有优异的抗辐照肿胀和抗腐蚀能力,是聚变堆、ADS和四代堆结构材料重要候选者之一.多尺度模拟在核武器自辐照损伤、压力容器辐照脆化、医学材料辐照损伤等方面有着广泛的应用.国际上围绕F/M FeCr合金辐照损伤开展了大量的多尺度模拟工作.论文概述了F/M FeCr合金辐照损伤多尺度模拟研究现状及进展,并针对目前存在的某些问题提出了解决建议. 关键词： 铁素体/马氏体FeCr合金 辐照损伤 多尺度模拟     

中能质子引起散裂反应的碎片质量分布研究

对 SHIELD程序进行了部分检验,利用SHIELD程序计算质子入射铅的薄靶产生的靶碎片的截面及质量分布和激发函数 ,计算结果较好地再现了实验数据 .并计算了 1 .6Ge V的质子轰击长 60 cm和直径20cm的铅靶的碎片质量分布. The test of part benchmark of SHIELD code was performed. The cross section, mass distribution and excitation function of the fragments (including residual nuclei) in the proton induced spallation reaction on thin Pb target at intermediate energy have been calculated by SHIELD code. And the results are in good agreement with experimental data. The fragment mass distributions from proton induced spallation reaction on thick Pb traget at incident energy 1.6 GeV were also presented.     

利用MSDM分析p+208Pb散裂反应产物

多步动力学模型(MSDM)研究中、高能质子引起的散裂反应分为3个过程:核内级联、粒子预平衡发射以及通过蒸发粒子和裂变方式的剩余激发核退激发过程.利用Ignatyuk能级密度公式代替MSDM模型中的费米气体能级密度公式,改进其研究质子入射引起散裂产物的形成截面.采用Ignatyuk能级密度公式MSDM研究p+208Pb散裂产物的电荷、质量分布以及产物核形成截面,结果很好地再现了实验数据,且比利用费米气体能级密度的MSDM结果好得多. The level density of Ignatyuk formula is introduced into the Many stages dynamics model ( (MSDM)) instead of Fermi-gas formula to improve the simulation of spallation fragments. The results of (MSDM) with Ignatyuk formula reproduced the experimental data well for the mass and charge distributions, the formation cross sections of isotopic product of proton-induced spallation on~(208)Pb. The calculations are in agreement with the experimental data and better than some simulations by MSDM with Fermi-gas ...     

(n,p)和(n,α)激发函数半经验计算方法

在En≤20MeV的情况下,忽略了粒子的二次发射过程,认为复合系统的形成截面是能量相关的,得到了理论模型清晰、公式形式简单的半经验计算方法.在靶核23≤A≤209的范围内,利用大量(n,p)和(n,α)反应的截面实验数据对可调参数进行了研究,得到了参数对靶核的N和Z以及入射能量的依赖关系.对得到的参数做了定性的解释,利用普适参数对(n,p)和(n,α)反应的激发函数做了预言,预言值在其误差范围内与实验数据一致. To simplify the calculation, some assumptions are considered at present work. The preequilibrium emission is the first step in the equilibrium process, which is characterized by exciton n=3 and "never come back" are considered at the preequilibrium emission process; the proton and alpha emissions are only competed with the neutron emission, the second particle emission is neglected. A semiempirical method of the cross section for (n, p ) and (n, α) reactions were obtained on the basis of evaporatio...     

中高能质子入射反应散裂碎片的半经验方法研究

简要分析了质子入射核反应的半经验研究方法,指出半经验研究方法应该建立在独立产额数据之上,而目前半经验研究方法主要是建立在以往的累积产额数据之上.通过对最新的实验得到的独立产额数据并结合MSDM的计算结果的分析,发现描述散裂质量分布的参数应该分为与能量有关和无关两个部分,并指出这与快过程平衡时间的不同有关. We analyzed the former solution of semi-empirical methods, which is first funded by G. Rudstam. On this basis, we pointed out that all the former solutions are basically based on so-called cumulative reaction data not on independent data. On the analysis of newly data measured by GSI, we founded that mass distribution of spalltion production could be divided to two parts: one is independent on induced-energy, but on the mass number of target; one is dependent on energy. Also, we argued that such...     

(n,p)激发函数一种新的半经验计算方法

基于核反应蒸发模型和预平衡激子模型,在一些近似条件下得到了入射能量小于20MeV的(n,p)的激发函数解析半经验表达式,靶核在23≤A≤209的范围内,利用大量(n,p)反应的截面实验数据对可调参数进行了研究,得到了参数对靶核的N和Z以及中子入射能量的依赖关系,对得到的参数做了定性的解释,利用普适参数对(n,p)反应的激发函数做了预言,预言值在其误差范围内与实验数据一致。     

中高能质子入射碎片质量分布研究

中高能质子轰击靶的碎片的质量分布是了解散裂中子靶的放射性累积和对靶材料性能的影响的一个重要方面.利用在级联-激子模型(CEM)的基础上发展起来的“多步动力学”模型(MSDM,Many Stage Dynamical Model)分别研究了入射质子能量为334,572,775,1200,1500和2600MeV轰击Nb靶,329,555,760,1200,1500和2600MeV轰击¹⁹⁷Au靶,160,230,271,322,533,660,759,1400,1600和2600MeV轰击Pb靶引起的碎片的质量分布,并和实验测量数据进行了比较.