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根据第一壁后聚变中子通量和能谱的空间分布和 ITER 可能输出的聚变功率、聚变中子产额、第一壁(产氚包层)之后的中子通量的蒙塔-卡罗中子输运(MCNP)计算,对氦冷却固体增殖剂中子学和产氚包层模块(NT-TBM-HCSB)的聚变中子诊断提出概念性设计,本设计提出用固定位置微型裂变室探测器和可移动封装薄箔活化分析系统测量中子倍增器之后、固体氚增殖剂中及其后的中子通量;用可移动天然金刚石探测器的紧凑型能谱仪测量中子能谱。     

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给出了氦冷却固体增殖剂中子学和产氚包层模块(NT-TBM-HCSB)聚变中子诊断的初步设计,提出了用固定或可移动位置微型裂变室探测器和可移动封装薄箔活化分析系统测量中子倍增器之后、固体氚增殖剂中及其后的中子通量;用可移动天然金刚石探测器的紧凑型能谱仪测量中子能谱。此诊断系统可用于中子倍增器的倍增效率,氚增殖层的增殖率与热核实验聚变堆的运行参数、加热和加料方式、磁流体不稳定性、能量约束以及大破裂等离子体参数和状态之间的工程和物理相关关系的实验研究,测量倍增层、氚增殖包层及其后进入屏蔽层的中子通量和能谱,并与MCNP计算相比较,优化和改进中子倍增器、氚增殖包层以及屏蔽层设计,提高氚增殖率。     

2.45 MeV小型D-D中子管准直屏蔽结构设计

为获取小角度出射的单能中子源,采用蒙特卡罗软件对小型D-D中子管产生的能量为2.45 MeV的4立体角中子源进行了准直屏蔽结构设计。准直屏蔽结构分为准直器和捕获穴,准直器采用铁+含硼聚乙烯+铅的三层过滤结构,用于屏蔽照射野外杂散中子,捕获穴主要功能是增加反方向中子的弹性散射次数,从而降低出射束低能散射中子的比例。通过MCNP模拟得到了准直器各层材料的最佳厚度和出射孔尺寸以及捕获穴最佳结构。经验证,中子照射野处2.45 MeV的中子通量比照射野外大三个量级,中子照射野处低能中子通量比2.45 MeV的中子通量低一个量级,墙壁外总剂量率（中子+）在2.5 Gy/h以下。该研究对于小角度单能中子源的快速获取具有一定的实用价值,获取的中子源可用于中子剂量仪器有效性检验、中子监测仪性能测试等方面的研究。     

基于低空成像信息的热红外成像仿真研究

提出了一种由低空飞行获取的以红外图像为数据源的中远红外仿真方法。首先通过大气辐射传输模型计算出测量条件下的程辐射和大气透过率,反演出地面温度,然后再由大气传输模型计算出仿真条件下的程辐射和大气透过率,并仿真卫星高度下的红外图像。以飞艇为平台,并搭载中远红外成像系统进行飞行,对获取的数据进行仿真模拟。试验结果表明,这种利用大气辐射传输模型和基于低空成像信息的遥感图像仿真方法可以用于模拟相同地区相同波段范围的卫星图像。     

产氚包层中聚变中子诊断系统的概念设计和计算

1 TBM中的中子通量和能谱 根据ITER等离子体可达到的运行参数和放电条件，用MCNP模拟计算D—D和D—T中子通量在中子产氚试验包层（NT-TBM）中随其小半径r的变化，如图1所示。     

单探头中子/伽马甄别能谱仪系统研制

针对放射性物质异常泄漏、防范核材料的非法转移和任意携带,提出一种基于单探头中子/伽马甄别能谱仪系统,实现敏感控制区中特殊核材料和放射性物质的监测。围绕核信号获取与数字化采集、辐射射线粒子甄别与能谱分析,开展基于FPGA与EJ299-33A的核数据采集电路设计、核信号处理算法设计和Matlab中子/伽马鉴别与能谱离线分析方法等关键技术研究。设计上位机软件实时处理辐射能谱数据,为正确做出应急预案提供数据参考。利用新型探测器和分型频谱数学模型在FPGA内部实现射线种类甄别,有效地解决了采用传统老式探测器和模拟电路的方法鉴别困难的问题,验证了分型频谱法在核信号处理上具有一定的可行性。开发完成集放射性种类判定、核素识别于一体的多功能集成中子/伽马探测器,在中子/伽马的混合辐射场中,既能实现射线甄别又能测量能谱,解决在复杂放射性环境中对不同射线种类的能谱分析和核素识别问题。     

HCSB DEMO 中子通量谱分析及活化片法测量系统概念设计研究

利用蒙特卡罗粒子输运程序(MCNP)对氦冷固态增殖剂包层聚变示范堆(HCSB DEMO)做了中子通量谱分析。根据中子通量谱特点选出活化片材料,根据跑兔系统和活化片法测中子通量的原理设计出适用于测量HCSB DEMO 增殖包层中子的活化片法测量系统,并对其各组成部分及功能做了说明。计算了活化片在测量系统辐照端辐照时的活化反应率、活化片特征γ 射线发射率及特征γ 计数率,并得到一套合理的测量方案,用于HCSB DEMO 包层中子的测量。     

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利用蒙特卡罗粒子输运程序(MCNP)对氦冷固态增殖剂包层聚变示范堆(HCSB DEMO)做了中子通量谱分析。根据中子通量谱特点选出活化片材料,根据跑兔系统和活化片法测中子通量的原理设计出适用于测量HCSB DEMO增殖包层中子的活化片法测量系统,并对其各组成部分及功能做了说明。计算了活化片在测量系统辐照端辐照时的活化反应率、活化片特征γ射线发射率及特征γ计数率,并得到一套合理的测量方案,用于HCSB DEMO包层中子的测量。     

中国散裂中子源在大气中子单粒子效应研究中的应用评估

由于缺少可用的散裂中子源,多年来我国在大气中子单粒子效应方面主要依靠模拟仿真和单能中子试验的方式开展研究.随着中国散裂中子源(CSNS)通过国家验收,基于CSNS开展大气中子单粒子效应研究成为可能.本文利用CSNS反角白光中子源开展多款静态随机存取存储器器件的中子单粒子效应试验,并与早期开展的高原大气试验结果进行对比,对CSNS在大气中子单粒子效应研究中的应用进行评估.结果表明,相同器件在CSNS反角白光中子源测得的单粒子翻转截面小于大气试验的结果,且不同器件的翻转截面与特征尺寸没有明显的单调关系.分析得到前者由于CSNS反角白光中子谱偏软;后者由于特征尺寸降低导致的临界电荷变小和灵敏体积变小对截面的贡献是竞争关系.针对截面偏小的问题,根据能谱差异分析了中子能量阈值对器件翻转截面的影响,发现能量阈值取12MeV进行计算时,器件在CSNS反角白光中子源和高原大气中子环境中能够得到较一致的截面.研究结果表明CSNS反角白光中子源能够用于加速大气中子单粒子效应试验.考虑到CSNS的运行功率正在逐步提高,且多条规划中的白光中子束线与大气中子能谱更为接近,预期未来CSNS将能更好地应用于大气中子单粒子效应研究.     

^6LiF中子夹心谱仪的研制

中子能谱是反应堆中子场特征参数之一。核反应所产生的粒子总能量与引起反应的中子入射方向无关，因此核反应法测量中子能谱不要求预先准直中子，特别适合于测量非点源中子能谱。66LiF夹心谱具有体积小、时间响应快、结构简单、使用方便等特点，在堆芯能谱测量时对中子场扰动较小，因此被广泛用来测量快堆中子能谱。文中研制了^6LiF中子夹心谱仪。     

中国散裂中子源反角白光中子束流参数的初步测量

中国散裂中子源(CSNS)已于2018年5月建设完工,随后进行了试运行.其中的反角白光中子束线(Back-n)可用于中子核数据测量、中子物理研究和核技术应用等多方面的实验.本文报道对该中子束的品质参数测量实验过程以及最终实验结果.实验主要采用中子飞行时间法,利用~(235)U,~(238)U裂变室和~6Li-Si探测器测量了中子能谱和中子注量率,又利用闪烁体-互补金属氧化物半导体探测系统测量了中子束斑的剖面,得到了该束线的初步实验测量结果.其中白光中子的全能谱测量范围eV—100 MeV,给出了不确定度分析;给出了中子注量率两个实验厅位置的满功率值;给出了白光中子在直径60 mm情况下的全能区束斑.通过与模拟结果的比较探讨了以上结果的合理性,并提出了改进计划.这些实验结果为以后该束线的核数据测量和探测器标定实验奠定了基础.     

准单能中子单粒子效应研究现状

对国际上用于单粒子效应(SEE)研究的准单能中子源进行了相关调研,对产生准单能中子源的7Li(p, n)7Be核反应、装置布局以及表征中子场性质的中子注量率、中子能谱、中子束流轮廓及其均匀性、热中子本底等参数的理论计算及实验测量进行了系统的介绍。进行准单能中子SEE实验要求中子源有较高的中子注量率水平、较大的束流轮廓、较好的束流均匀性以及较低的热中子本底,并且能测量出精确的中子能谱。对准单能中子SEE实验过程以及三种中子SEE截面的尾部修正方法进行了介绍。     

Altitude variation of cosmic ray nucleons derived from feynman scaling hypothesis

The differential proton spectra at different atmospheric depths and the differential neutron spectrum at sea level have been calculated using the scaling hypothesis of Feynman for hadronic inclusive reaction at high energies. In evaluating such values we used the primary nucleon spectrum of Grigorov et al. It is found that the derived spectra fit well the experimental data given by different authors. The estimated neutron-proton flux ratio against atmospheric depths is in accord with the measured data surveyed by Aguirre.The authors express their sincere thanks to Dr. A. Liland for sending his works.     

Neutron dosimetry in low-earth orbit using passive detectors

This paper summarizes neutron dosimetry measurements made by the USF Physics Research Laboratory aboard US and Russian LEO spacecraft over the past 20 years using two types of passive detector. Thermal/resonance neutron detectors exploiting the 6Li(n,T) alpha reaction were used to measure neutrons of energies <1 MeV. Fission foil neutron detectors were used to measure neutrons of energies above 1 MeV. While originally analysed in terms of dose equivalent using the NCRP-38 definition of quality factor, for the purposes of this paper the measured neutron data have been reanalyzed and are presented in terms of ambient dose equivalent. Dose equivalent rate for neutrons <1 MeV ranged from 0.80 microSv/d on the low altitude, low inclination STS-41B mission to 22.0 microSv/d measured in the Shuttle's cargo bay on the highly inclined STS-51F Spacelab-2 mission. In one particular instance a detector embedded within a large hydrogenous mass on STS-61 (in the ECT experiment) measured 34.6 microSv/d. Dose equivalent rate measurements of neutrons >1 MeV ranged from 4.5 microSv/d on the low altitude STS-3 mission to 172 microSv/d on the ~6 year LDEF mission. Thermal neutrons (<0.3 eV) were observed to make a negligible contribution to neutron dose equivalent in all cases. The major fraction of neutron dose equivalent was found to be from neutrons >1 MeV and, on LDEF, neutrons >1 MeV are responsible for over 98% of the total neutron dose equivalent. Estimates of the neutron contribution to the total dose equivalent are somewhat lower than model estimates, ranging from 5.7% at a location under low shielding on LDEF to 18.4% on the highly inclined (82.3 degrees) Biocosmos-2044 mission.     

Equivalent dose measurements on board an Armenian Airline flight and Concorde (correction of Concord) (9-17 km)

The results of investigations of the neutron component (E=1–10 MeV) of cosmic radiation on board the “Armenian Airlines” aircrafts using nuclear photoemulsion are presented. The emulsions were exposed on the flights from Yerevan to Moscow, St.-Petersburg, Beirut, Athens, Frankfurt, Amsterdam, Paris and Sofia, and on Concord supersonic flights from Paris to New York.

The dependence of the neutron fluxes, and on absorbed and equivalent doses on the flight parameters were investigated. On the flights of the supersonic Concord, with an altitude of 17 km, the neutron fluxes were essentially higher in comparison to those measured on Armenian airliners. It is interesting to note, that the neutron flux and equivalent dose rate decrease with altitude up to 470 km in space, for example, on board the STS-57.

The shape of the differential energy spectrum for fast neutrons is the same on all Armenian airlines flights, but significantly different at 17 km altitude, where the flux in the energy region above 3 MeV is increasing.     

The effect of fast neutrons on the conductance of single-crystal silicon

The dependence of variation of the specific conductance of single-crystal silicon on the fast neutron fluence is calculated. The results of calculations are compared with the experimental data obtained in two channels of an IRT-T reactor with different neutron spectra. These experimental data are also discussed. The fast neutron fluence was controlled using threshold sulfur activation detectors. The specific electrical resistance was measured by a 4-probe method. The calculation data are in good agreement with experiment and show that the variation of the specific conductance due to exposure to fast neutrons is in direct proportion to the fluence of these neutrons. The proportionality coefficient depends on the neutron spectrum, but is independent of the initial specific conductance. In so doing, it makes no difference, whether silicon was previously irradiated or not.     

Monitoring method for neutron flux for a spallation target in an accelerator driven sub-critical system

In this paper, we study a monitoring method for neutron flux for the spallation target used in an accelerator driven sub-critical(ADS) system, where a spallation target located vertically at the centre of a sub-critical core is bombarded vertically by high-energy protons from an accelerator. First, by considering the characteristics in the spatial variation of neutron flux from the spallation target, we propose a multi-point measurement technique,i.e. the spallation neutron flux should be measured at multiple vertical locations. To explain why the flux should be measured at multiple locations, we have studied neutron production from a tungsten target bombarded by a 250 Me V-proton beam with Geant 4-based Monte Carlo simulations. The simulation results indicate that the neutron flux at the central location is up to three orders of magnitude higher than the flux at lower locations. Secondly, we have developed an effective technique in order to measure the spallation neutron flux with a fission chamber(FC), by establishing the relation between the fission rate measured by FC and the spallation neutron flux. Since this relation is linear for a FC, a constant calibration factor is used to derive the neutron flux from the measured fission rate. This calibration factor can be extracted from the energy spectra of spallation neutrons. Finally, we have evaluated the proposed calibration method for a FC in the environment of an ADS system. The results indicate that the proposed method functions very well.     

中子单粒子效应研究现状及进展

回顾了中子单粒子研究的国内外发展情况,介绍了近几年西北核技术研究所在西安脉冲堆开展的低能中子单粒子效应研究进展。比较了稳态与脉冲工况下中子单粒子效应的异同性;分析了含有SRAM结构器件随着特征尺寸的减小,中子单粒子效应敏感性加剧的物理机制。分析认为目前中子单粒子效应已成为小尺寸大规模互补金属氧化物半导体器件的主要中子效应表现;中子辐射效应研究中,除了位移损伤效应以外还必需重视由中子电离造成的中子单粒子效应。     

Experimental neutron flux measurements with a diamond detector at the QUINTA setup

The operational capability of a diamond detector used to measure the neutron spectrum by the response function on the QUINTA setup [1] installed at the proton beam of the phasotron [2] (Laboratory of Nuclear Problems, Joint Institute for Nuclear Research) was demonstrated in the energy interval of 2.1–20 MeV. The neutron-flux count rate was measured. The energy of neutrons was estimated at 7.4–25.7 MeV based on the diamond-detector response spectrum. The dependence of the diamond-detector response spectra on the angle between the proton beam and the line going through the detector and the center of the QUINTA setup was investigated. The angular anisotropy of the neutron flux was demonstrated. Measurements at different distances from the detector to the QUINTA setup were performed.