共查询到19条相似文献,搜索用时 218 毫秒
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介质型快中子探测器的中子直照响应对其设计和实际应用具有重要影响。利用Geant4编制Monte-Carlo模拟程序对此型探测器的中子直照响应进行了计算。模拟了探测器芯子常用材料在中子入射时带电重粒子的发射情况,发现电荷收集极、卡阈吸收片和后高压绝缘层材料的选择对中子直照响应特性有直接影响。在现有的以聚四氟乙烯为卡阈吸收片和后高压绝缘层材料的探测芯子中,直照响应给总的中子灵敏度带来约6%的贡献。提出了一种使用高电阻率石墨作为卡阈吸收片和后高压绝缘层材料的探测芯子的优化结构,可有效降低中子直照响应。 相似文献
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15 MeV电子直线加速器驱动的光中子源装置,将用于中国科学院战略性先导科技专项“钍基熔盐堆”中的核数据初步测量工作、中子探测器的研制和反应堆相关材料的辐照研究等。光中子源的中子能谱是连续的,中子能量通过中子飞行时间法测量得到,需要利用吸收片确认中子吸收峰,刻度飞行时间,计算等效飞行距离,扣除实验本底等,而实验本底的扣除对最终总截面计算有很大的影响。因此通过Geant4蒙特卡罗模拟软件构建了包括中子源、吸收片在内的模拟实验环境;研究了不同吸收片的吸收谱和吸收片厚度的关系,同理论计算值进行了比较,给出了推荐的吸收片厚度值;模拟计算了中子飞行时间谱,并和实验测量结果比较,确定中子等效飞行距离为5.70 m。Geant4的理论计算也可以模拟出多吸收片本底函数曲线,可用于实验数据的本底扣除和误差分析。实验测量、模拟分析以及理论公式计算的吸收片厚度和中子飞行时间参数得到了完全一致的结果,验证了实验测量的可靠性。A photo-neutron source driven by a 15 MeV electron LINAC is built for the "Strategic Priority Research Program" of the Chinese Academy of Sciences-the "thorium-based molten salt reactor" project to conduct the nuclear data measurement work,develop neutron detector and carry out reactor material irradiation studies.Since the neutron energy spectrum is continuous,the neutron energy is measured by the time of flight (TOF) method,and neutron filters are needed to confirm absorption peaks,calibrate the TOF,calculate the equivalent flight distance,and remove the experimental background which has great influence on the calculation accuracy of the total cross section.Based on the Monte Carlo simulation tool,Geant4 a simulation environment is set up,including neutron source and neutron filters,to study the energy absorption spectra and thickness of different filters and recommended data for the thickness are provided.The neutron TOF spectra are simulated and compared with experimental measurement,deciding the equivalent TOF distance to be 5.7 m.Geant4 can also simulate the background curve of multiple filters and be used to remove background and analyze errors for the experimental data.All the experiments,simulation and theoretical calculation show consistent results on filter thickness and neutron TOF parameters,indicating the accuracy of the measurement. 相似文献
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利用蒙特卡罗程序FLUKA模拟计算了聚乙烯慢化球和辅助材料慢化球对低能中子到高能中子的响应函数曲线。结果表明,对纯聚乙烯球来说,随着聚乙烯层厚度的增加,响应曲线峰逐步右移,峰值在高能区有所下降,对20 Me V以上的中子,无论纯聚乙烯球的尺寸有多大,其响应均下降到很低的程度;对辅助材料慢化球来说,中子能量小于1 Me V时,辅助材料慢化球与聚乙烯慢化球的响应曲线相似,但当中子能量大于20 Me V时,中子与辅助材料层发生(n,xn)反应,慢化球的响应呈显著上升趋势。分析计算结果,最终能够确定宽能谱多球中子谱仪的尺寸组合。 相似文献
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介质型脉冲高能中子探测器 总被引:2,自引:0,他引:2
首次报道一种基于反冲质子法和高速带电粒子在物质表面引起二次电子发射的高能中子探测方法,研制成功的新一代强流脉冲高能中子探测器,即介质型脉冲高能中子探测器.与传统的强流脉冲中子探测器相比,该探测器对中子的探测及信号的传输过程是在介质中完成的,因而不需要真空和高压也可以正常工作,并具有多项优异的物理性能.该探测器的输出信号来自于高能中子在聚乙烯转换靶产生的高能反冲质子和这些质子穿越电荷收集极表面时产生的部分二次电子.选择适当的卡阈吸收片和电荷收集极材料,二次电子在探测灵敏度中的份额及其随能量的变化可由实验测定. 相似文献
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在星光Ⅲ实验装置上开展皮秒激光脉冲中子源实验,使用液体闪烁体探测器测得较好的中子信号,利用飞行时间法获得中子的能量/时间分布,通过示波器电压时间积分与阻抗之比得到不同能量段的电荷值。建立液体闪烁体探测器Geant4计算模型,通过实际打靶情况与标定情况下液体闪烁体探测器出光口收集到的可见光光子数之比,结合标定的灵敏度数据,获得液体闪烁体探测器对不同能量中子的灵敏度。计算得到源发射的中子能谱,能量在1 MeV以上的液体闪烁体探测器方向测得的中子产额为1.04108 sr-1。 相似文献
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由于对γ射线灵敏度低,而且可在很宽的范围内中子能量响应比较平坦,长计数管在中子产额的测量中得到了广泛的应用。为了提高探测效率,一般用BF3或^3He正比管外包围一定厚度的石蜡或聚乙烯慢化体来构成长计数管探测系统。建立的长计数器主要是针对中子管产生的DD(2.4MeV)或DT(14.1MeV)或两种能量混合的脉冲中子进行测量。为了达到探测系统设计要求,首先详细模拟了慢化体尺寸及结构对探测效率的影响,以便对探测器系统的加工制作提供依据。根据模拟结果建立了探测器,从实验上对探测器的性能进行了测量。 相似文献
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在ADS散裂靶系统的优化设计中,蒙特卡罗方法结合可靠的散裂反应理论模型进行中子学计算具有重要的作用。本工作利用Geant4程序中的INCLXX模型、BIC模型以及BERT模型和FLUKA程序分别模拟了597 MeV和1 500 MeV质子轰击薄铅靶不同出射角度的中子双微分截面,500,1 500 MeV质子轰击厚铅靶不同出射角度的中子双微分产额,以及400,600,800,1 000和1 200 MeV质子轰击厚钨靶在反角方向(175 °)的中子双微分产额,并与实验数据进行比较。研究表明,对于薄铅靶,Geant4程序的INCLXX模型和FLUKA程序模拟结果与实验符合得更好。能量在10~40 MeV范围内,BIC模型模拟结果明显高于实验数据,而BERT模型模拟结果略微低于实验数据。对于厚铅靶,在40 MeV左右所有的模拟结果都低于实验数据。对于厚钨靶,Geant4程序的BIC模型和FLUKA程序与实验数据符合得较好,INCLXX模型在能量高于60 MeV时模拟结果低于实验数据,BERT模型与实验数据差异较大。总体来看,Geant4程序的INCLXX模型和FLUKA程序进行ADS散裂靶相关的中子学的计算是合理和可靠的。The reliable Monte Carlo simulation codes coupled with nuclear reaction models play an important role in the neutronic calculation for the design and optimization of the ADS spallation target. In this work, the double differential cross sections at different angles produced from a thin lead target bombarded with 597 and 1 500 MeV protons, the neutron energy spectra at different angles produced from a thick lead target bombarded with 500 and 1 500 MeV protons, and the neutron energy spectra in the backward direction(175°) produced from a thick tungsten target bombarded with 400, 600, 800, 1 000 and 1 200 MeV protons are calculated with the Geant4 code coupled INCLXX, BIC and BERT models and the FLUKA code. The calculations are compared with the available experimental data. The results show that, for the thin lead target, the calculations with the Geant4 coupled INCLXX model and FLUKA code well reproduce the experimental results. In a energy range from 10 to 40 MeV, BIC model obviously overestimates the experimental results, and BERT model slightly underestimates the experimental results. For the thick lead target, all of the calculations underestimate the experimental results around 40MeV. For the thick tungsten target, the Geant4 coupled BIC model and FLUKA code well reproduce the experimental results. INCLXX model underestimates the experimental results above 60 MeV. BERT model bad reproduces the experimental results. Overall, the neutronic calculations with the Geant4 code coupled INCLXX model and FLUKA code for the ADS spallation target is reasonable and reliable. 相似文献
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Radiation effects on MOS and bipolar devices by 8 MeV protons, 60 MeV Br ions and 1 MeV electrons
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The radiation effects of the metal-oxide-semiconductor
(MOS) and the bipolar devices are characterised using 8~MeV protons,
60~MeV Br ions and 1~MeV electrons. Key parameters are measured {\it
in-situ} and compared for the devices. The ionising and nonionising
energy losses of incident particles are calculated using the Geant4
and the stopping and range of ions in matter code. The results of
the experiment and energy loss calculation for different particles
show that different incident particles may give different
contribution to MOS and bipolar devices. The irradiation particles,
which cause larger displacement dose within the same chip depth of
bipolar devices at a given total dose, would generate more severe
damage to the voltage parameters of the bipolar devices. On the
contrary, the irradiation particles, which cause larger ionising
damage in the gate oxide, would generate more severe damage to MOS
devices. In this investigation, we attempt to analyse the
sensitivity to radiation damage of the different parameter of the
MOS and bipolar devices by comparing the irradiation experimental
data and the calculated results using Geant4 and SRIM code. 相似文献
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研究了成像板辐射图像测量的基本原理及其物理机制,并将其应用于伽马图像测量。建立了MS,SR和TR三种类型成像板数值模拟模型,分别使用MCNPX程序和基于Geant4开发的NPE程序计算了三种成像板对不同能量伽马射线的能量沉积,计算结果表明:SR和MS成像板比TR成像板能量沉积在低能部分大3~5倍,高能部分大7~9倍。实验测量了MS成像板灵敏度随铜膜厚度的变化关系,测量结果与理论计算结果有较好的一致性。理论与实验结果表明:成像板伽马图像测量的空间分辨力优于50 m。 相似文献
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利用编制的快中子照相数值模拟程序(FNRSC)模拟计算了入射中子能量为14 MeV时,厚度5—300 mm闪烁体内次级中子对快中子图像质量的影响,结果表明闪烁体厚度d<50mm时,次级中子对图像的影响强烈依赖于闪烁体厚度,而当d>50 mm时,次级中子对图像的影响趋于饱和.将文献中利用蒙特卡罗中子-光子输运程序(MCNP)计算的次级中子对图像影响和文中计算结果进行了对比,给出了二者存在差异的主要原因:次级中子分布对入射中子空间分布的强烈依赖性;能量沉积和荧光输出这两种计算方法对
关键词:
14 MeV中子
快中子照相
次级中子
Monte Carlo模拟 相似文献
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超快中子探测器是ICF聚变反应速率测量系统的核心部件。利用蒙特卡罗粒子输运工具包Geant4模拟了一种超快中子探测器——BC-422型闪烁探测器的中子探测过程,计算出了几种厚度的BC-422型闪烁体的探测效率、输出光信号强度和时间分辨力;对比了闪烁体的2种不同反射表面对输出光信号强度和时间分辨力的影响。计算的结果显示:设计适当的BC-422型闪烁探测器能够测量的最低中子产额在108量级,对DT中子的信号时间分辨力好于20 ps,对DD中子的信号时间分辨力达到30 ps,能够用于大型激光装置及其原型的聚变反应速率测量。 相似文献
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Ke Li Jian-Rong Zhou Xiao-Dong Wang Tao Xiong Ying Zhang Yu-Guang Xie Liang Zhou Hong Xu Gui-An Yang Yan-Feng Wang Yan Wang Jin-Jie Wu Zhi-Jia Sun Bi-Tao Hu 《中国物理C(英文版)》2016,40(7):076002-076002
With new generation neutron sources, traditional neutron detectors cannot satisfy the demands of the applications, especially under high flux. Furthermore, facing the global crisis in ~3He gas supply, research on new types of neutron detector as an alternative to ~3He is a research hotspot in the field of particle detection. GEM(Gaseous Electron Multiplier) neutron detectors have high counting rate, good spatial and time resolution, and could be one future direction of the development of neutron detectors. In this paper, the physical process of neutron detection is simulated with Geant 4 code, studying the relations between thermal conversion efficiency, boron thickness and number of boron layers. Due to the special characteristics of neutron detection, we have developed a novel type of special ceramic n THGEM(neutron THick GEM) for neutron detection. The performance of the n THGEM working in different Ar/CO_2 mixtures is presented, including measurements of the gain and the count rate plateau using a copper target X-ray source. A detector with a single n THGEM has been tested for 2-D imaging using a ~(252)Cf neutron source. The key parameters of the performance of the n THGEM detector have been obtained, providing necessary experimental data as a reference for further research on this detector. 相似文献
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采用Monte Carlo程序Geant4对激光固体靶相互作用正电子产生进行了研究。研究了超热电子能量分布函数对正电子产生的影响,结果表明采用不同的分布函数,最多可致正电子产额约3倍的差异,分布函数的最大截止能量在30 MeV以上时正电子产额趋于饱和。研究了正电子产生与超热电子发散角的关联,结果表明发散角模型对正电子产额影响不大,而正电子角分布对超热电子发散角较为敏感,且靶背鞘场对正电子发散角的减小贡献巨大。模拟结果显示靶厚度的增加可导致正电子发散角的增大,而当靶厚度超过2mm时,发散角基本保持不变。此外,模拟了超热电子发散角、靶厚度及靶背鞘场对正电子电子份额比及正电子γ份额比角分布的影响。 相似文献
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《中国物理 B》2015,(10)
For the proper interpretation of the experimental data produced in slow positron beam technique, the positron implantation properties are studied carefully using the latest Geant4 code. The simulated backscattering coefficients, the implantation profiles, and the median implantation depths for mono-energetic positrons with energy range from 1 keV to 50 keV normally incident on different crystals are reported. Compared with the previous experimental results, our simulation backscattering coefficients are in reasonable agreement, and we think that the accuracy may be related to the structures of the host materials in the Geant4 code. Based on the reasonable simulated backscattering coefficients, the adjustable parameters of the implantation profiles which are dependent on materials and implantation energies are obtained. The most important point is that we calculate the positron backscattering coefficients and median implantation depths in amorphous polymers for the first time and our simulations are in fairly good agreement with the previous experimental results. 相似文献
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计算了多脉冲相对论强流电子束入射钽-石墨叠靶的能量沉积和轫致辐射谱。能量沉积采用Geant4程序计算,轫致辐射谱根据基本的辐射理论和蒙特卡罗方法计算。结果显示,各层的热区能量沉积呈由大到小的递减分布,截面轫致辐射分布和电子束径向分布主要受钽层的影响。石墨层的低能量沉积率和高热容能改善叠靶的性能。对于单脉冲,钽-石墨层厚比为1∶1时,石墨能全部吸收相邻钽层的热沉积,轫致辐射效率为35.4%;4脉冲情况下,钽-石墨层厚比应为1∶13,总轫致辐射效率降到19.9%。考虑轫致辐射剂量和质量,钽-石墨两者的厚度比为1∶5时,钽层的总厚度应为1.2 mm;当钽-石墨层厚比为1∶10时,钽层的总厚应降到0.7 mm。 相似文献