1 MeV中子在Si和SiO2中非电离能量损失和电离能量损失的蒙特卡罗计算

在现有实验数据的基础上结合多种理论，给出了计算中子在材料中非电离能量损失（NIEL）和电离能量损失（IEL）的蒙特卡罗（MC）计算方法，利用此方法编写的计算程序可以对任意材料、多层结构中中子产生的NIEL和IEL以及空位和声子分布等进行计算。对硅和二氧化硅材料1MeV中子损伤进行的计算结果表明，此方法是可行的。     

InGaAsP器件质子位移损伤等效性研究

对基于非电离能量损耗（NIEL）的位移损伤等效性研究方法进行了讨论,计算了不同能量质子在InGaAsP材料中的NIEL。利用解析方法对库仑散射引起的NIEL进行了计算,分析了不同库仑散射模型的适用范围,并利用Monte-Carlo方法对核反应引起的NIEL进行了计算。以InGaAsP多量子阱激光二极管为研究对象,开展了4、5和8 MeV质子辐照实验,获得了激光二极管的阈值电流损伤系数。研究结果表明：实验用不同能量质子辐射环境下的阈值电流损伤系数测试结果与NIEL理论计算结果之间呈线性关系。     

CIAE Application of Patent in 2004

高气压组织等效电离室内中子（尤其是高能中子）的输运过程是中子、光子、质子以及电子等粒子的复杂的偶合输运过程，使用Geant4程序模拟该输运过程，并在Linux6．2操作系统下利用Geant4软件计算了有铝层和无铝层，次外层材料为A—150组织等效材料，厚度分别为2、5、10、20mm，平行入射的单能中子的能量分别为1、100、500keV和2、10、14、20、30、50、80、100MeV时，以及有铝层、次外层材料为聚乙烯，厚度为5mm，平行入射的单能中子的能量分别为0．0253eV、100eV、lkeV、100keV、500keV、2MeV、10MeV、14MeV、20MeV、30MeV、100MeV时的中子沉积能量。在中高能入射中子能量条件下，计算结果与实验数据基本符合。     

半导体材料电子非电离能损的分析法计算

非电离能损(NIEL)可用于预测半导体器件在空间辐射环境中位移损伤引起的性能参数退化,计算模型选用经典NIEL模型,计算了能量范围为100 keV～200 MeV的电子入硅、锗、砷化镓材料的NIEL,及微分散射截面、林哈德因子和位移原子数量等信息.考虑到经典NIEL模型在入射电子能量较低的情况下得出的位移原子数量不够精确,所以用分子动力学(MD)方法加以改良,得出在低能区域更真实的位移原子数量,用于修正经典NIEL,并分析了MD模型下新的位移阈值能对计算结果的影响.     

SND-S1型液体闪烁体光输出的能量响应

采用不同能量的γ射线标准源及D-D、D-T核反应的单能中子源分别测定了新型液体闪烁体SND-S1的光输出随粒子能量的变化,采用Monte-Carlo程序Penelope模拟计算了¹³⁷Csγ射线的能量分布谱,最大康普顿电子能量的计算值和实验值相差2.7%。将实验结果与文献值作了比较,能量低于3MeV时,符合较好;能量高于6MeV时,略有差别。结果表明,液体闪烁体的光输出与电子能量呈线性正比关系,而与中子能量呈非线性关系。     

质子在氮化镓中产生位移损伤的Geant4模拟

材料受到辐照时产生的位移损伤会导致其微观结构发生变化,从而使其某些使用性能退化,影响其使用效率,减短其使用寿命。利用Geant4模拟了质子在氮化镓中的输运过程,计算了1、10、100、500 MeV能量质子入射氮化镓材料产生的初级撞出原子的种类、能量信息及离位原子数。获得了10 MeV质子产生的位移缺陷分布;计算了4种能量质子入射氮化镓材料产生的非电离能量损失(NIEL);研究了质子产生位移损伤过程的影响要素。研究发现,入射质子能量对其在材料中产生的初级撞出原子的种类、能量、离位原子数等信息有着非常大的影响;单位厚度所沉积NIEL随着入射质子能量的增大而减小;10 MeV质子入射氮化镓所产生的离位原子数随入射深度的增加而增加,但在超出其射程范围以外有一巨大回落;能量并不是影响质子与氮化镓靶材料相互作用的唯一因素。     

能量从10 keV到300 MeV的电子和光子在物质中若干物理参数计算程序

本工作提供一组计算程序,可计算电子的能量损失(碰撞损失、轫致辐射损失、阻止本领)及射程、电子轫致辐射光子能谱及轫致辐射光子数目分布、电子和光子的反应几率(电子轫致辐射几率、电子同电子碰撞几率;光子康普顿散射几率、核场中对生成几率)。物质组成可分为单一元素、化合物或混合物。能量范围从10 keV到300 MeV分为75个间隔。以数据表的形式给出上述诸量。结果满意。     

柔性倒置赝型三结太阳电池高能质子辐射效应研究

为考察柔性薄膜GaInP/GaAs/InGaAs倒赝型三结（IMM3J）太阳电池的抗辐照性能,本文对其进行了1、3、5 MeV高能质子辐照。SRIM模拟结果表明,1、3、5 MeV质子辐照在IMM3J电池中造成均匀的位移损伤。光特性(LIV)结果表明,开路电压(Voc)、短路电流(Isc)和最大输出功率(Pmax)与质子注量呈对数退化规律。通过非电离能量损失（NIEL）将不同能量质子的注量转化为位移损伤剂量（DDD）,结果显示,Voc和Pmax与DDD呈对数退化规律,而Isc遵循两种不同的退化规律。光谱响应测试证明,GaInP子电池具有优异的抗辐照性能,3个子电池中InGaAs(10 eV)子电池的抗辐照性能最差。     

γ射线探测器能量响应标定技术

叙述了γ射线探测器能量响应的标定原理和方法，即利用Compton散射将强⁶⁰Co源的1.25MeVγ射线转换为0.36~1.02MeV(25°~90°)范围内任意能量的系列单能γ射线；采用辐射屏蔽技术和提高能量分辨率方法对γ射线探测器进行了该能区的能量响应标定；通过MCNP程序对探测器的能量沉积趋势和不同散射角散射γ射线的能量分布进行模拟计算。结果表明：该标定系统信噪比达到了20∶1左右，能量分辨率约为6%，0.66MeV的灵敏度与标准¹³⁷Cs源直照标定的灵敏度基本一致。     

某轻混凝土γ屏蔽积累因子的计算

使用蒙特卡罗程序EGS4计算了光子能量范围0.015~15MeV、屏蔽厚度达40个平均自由程的某核电厂中使用的轻混凝土的γ照射量积累因子,程序计算中考虑了轫致辐射、荧光效应和相干（瑞利）散射对积累因子的影响。使用G-P近似拟合公式对γ屏蔽积累因子计算结果进行拟合计算,给出了相应的积累因子G-P拟合公式的拟合参数。利用此方法可得到此种轻混凝土的任意光子能量和屏蔽厚度的γ屏蔽积累因子。     

Radiation Effects on GaAs Charge Coupled Devices with High Resistivity Gate Structures

The results of a study on the effects of 1 MeV electrons and 1 MeV neutrons on the operation of high speed GaAs Charge Coupled Devices (CCDs) are presented. Radiation-induced trapping levels are characterized using a linear array CCD structure and the periodic pulse technique. 1 MeV electron irradiation introduced traps at 0.1 eV and 0.39 eV with bulk trap introduction rates of 1 cm-1 and 0.33 cm-1, respectively. The devices were irradiated to a maximum fluence of 9×1014 electrons/cm2. 1 MeV neutron irradiation introduced an electron trap level at 0.64 eV with a bulk trap introduction rate of 0.5 cm-1. Catastrophic device failure occurred at neutron fluences of 6×1013 neutrons/cm2. Device charge transfer efficiency was characterized pre- and post-irradiation over the temperature range of 80°K to 300°K.     

Radiation Damage in Semiconductor Detectors

A survey is presented of the important damage-producing interactions in semiconductor detectors and estimates of defect numbers are made for MeV protons, neutrons and electrons. Damage effects of fast neutrons in germanium gamma ray spectrometers are given in some detail. General effects in silicon detectors are discussed and damage constants and their relationship to leakage current is introduced.     

Photo-Neutron Production in Heliotron-E

Photo-neutron emission in H₂ and He discharges was observed in the initial ohmic heating experiments of the Heliotron-E. Typical total neutron yield was 10⁹ neutrons per pulse under high level of runaway electrons (≧10 MeV). Neutron flux was localized near the limiters. Energy spectrum of neutrons was continuous up to about 2 MeV. The radioactive nuclides in the limiters and the vacuum chamber irradiated by runaway electrons showed that ⁵⁸Ni(γ, n) ⁵⁷Ni and ⁵³Cr(γ, n)⁵¹Cr reactions had occurred, proving that the photo-disintegration process was the source of neutron flux.     

Study of n- and p-Type Silicon Exposed to Highly Energetic Radiation

For an understanding of displacement effects in semiconductors, it is important to establish a correlation of the magnitude of these effects with various types of radiation. A study has been made of the effect of highly energetic radiation on n-type silicon using two techniques. First, with electron-spin resonance studies, the energy dependence of formation of the Si-Bl center at 80° and 300°K by 1.5, 2.5, 5, and 30 MeV electrons and by reactor neutrons has been determined. In addition, the energy dependence of the production of the divacancy by electrons with energies between 2.5 and 30 MeV in n-type silicon have been obtained. Second, using galvanomagnetic techniques, information has been obtained on the irradiation response and subsequent recovery during annealing of the conductivity, Hall coefficient, and Hall mobility of n-and p-type silicon. The samples were bombarded at 80°K with 5 to 30 MeV electrons and isochronally annealed to 400°K. A considerable amount of annealing was observed in all cases, but the recovery was never complete.     

50MeV／u^12C离子实验靶区中子注量率的测量

用阈探测器中子活化法测量了50MeV/u~(12)C离子实验靶区出射的热中子以及E_n分别大于6、11、20、50MeV的中子注量率。     

Preliminary Experiments on Accelerator-Driven Subcritical Reactor with Pulsed Neutron Generator in Kyoto University Critical Assembly

A series of preliminary experiments on an accelerator-driven subcritical reactor (ADSR) with 14 MeV neutrons were conducted at Kyoto University Critical Assembly (KUCA) with the prospect of establishing a new neutron source for research. A critical assembly of a solid-moderated and -reflected core was combined with a Cockcroft-Walton-type accelerator. A neutron shield and a beam duct were installed in the reflector region for directing as large a number as possible of the high-energy 14MeV neutrons generated by deuteron-tritium (D-T) reactions to the fuel region, since the tritium target is located outside the core. And then, neutrons (14MeV) were injected into a subcritical system through a polyethylene reflector. The objectives of this paper are to investigate the neutron design accuracy of the ADSR with 14MeV neutrons and to examine experimentally the neutronic properties of the ADSR with 14MeV neutrons at KUCA. The reaction rate distribution and the neutron spectrum were measured by the foil activation method for investigating the neutronic properties of the ADSR with 14 MeV neutrons. The eigenvalue and fixed-source calculations were executed using a continuous-energy Monte Carlo calculation code MCNP-4C3 with ENDF/B-VI.2 for the subcriticality and the reaction rate distribution, respectively; the unfolding calculation was done using the SAND-II code coupled with JENDL Activation Cross Section File 96 for the neutron spectrum. The values of the calculated subcriticality and the reaction rate distribution were in good agreement with those of the experiments. The results of the experiments and the calculations demonstrated that the installation of the neutron shield and the beam duct was experimentally valid and that the MCNP-4C3 calculations were accurately carried out for analyzing the neutronic properties of the ADSR with 14MeV neutrons at KUCA.     

A ctivation measurement of neutron distribution in intermediate energy heavy ion target area

The distribution of neutrons produced by the reaction of 50MeV/u ^12C-ion on a thick Cu target are studied.The neutrons are measured with threshold activation detectors.Al.F,C,Al and In activation samples were used to measure neutrons with energy greater than 7,11,20,50MeV and thermal neutrons,respectively,The fluence rate,energy and angular distributions of neutrons,total neutron yield of 12C-ion and the emission rate in the forward direction of neutrons over 11 and 20MeV were obtained.     

国产Am-Be中子源能量低于1.5MeV中子所占份额的实验测定

本工作提出了测定Am Be中子源发射的能量低于1.5MeV中子所占份额的1种实用实验方法。用4.438MeVγ射线伴随的飞行时间法测量了中子源的局部中子谱（n₁群中子）。通过已准确测量的中子源发射4.438MeVγ射线与中子强度的比值(R=R_γ/S_n)和n₁群中子谱与测量的能量为1.5MeV以上中子总谱在3.2MeV能量处归一后的面积比值,求得国产Am-Be中子源能量低于1.5MeV中子的所占份额为(19.1±1.9)%。     

Single Event Upsets in NMOS Microprocessors

Three advanced 16-bit NMOS microprocessors have been observed to suffer single event upset at a rate varying between one upset for every 8 × 1010 to one for every 2 × 1012 n/cm2-upset for cyclotron-produced neutrons with an average energy of 14 MeV. These rates are expected to vary, probably upward, with different types of programs. The errors are inferred to occur in memory-like components of the microprocessors. Many of the errors caused the microcomputer to cease normal operations. This is the first direct experimental verification of logic upsets in microprocessors from neutrons.     

Shielding data for 100-250 MeV proton accelerators: Attenuation of secondary radiation in thick iron and concrete/iron shields

Double differential distributions of neutrons produced by 100, 150, 200 and 250 MeV protons stopped in a thick iron target were calculated with the FLUKA Monte Carlo code at four emission angles: forward, 45°, transverse and 135° backwards. The attenuation in thick iron shields of the dose equivalent due to neutrons, protons, photons and electrons was also calculated. The contribution to the total ambient dose equivalent from photons and protons is limited to a few percent at maximum. Source terms and attenuation lengths are given as a function of energy and emission angle, along with fits to the Monte Carlo data, for shallow depth and deep penetration in the shield. A brief discussion of simulations performed with composite iron/concrete shields is also given, showing the need for further investigations.