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不同成分中子参考辐射场是对中子防护材料性能测试的基本条件。为获得较理想的测试中子防护材料的中子参考辐射场,构建基于3He正比计数管的多球中子能谱测量系统,对基于241Am-Be和252Cf中子源的中子辐射场慢化情况进行MCNP模拟和能谱实验测量。为准确判断实验室校准参考位置的中子散射情况,基于多球中子能谱测量系统,开展了中子散射成分测量。采用ICRP推荐的注量-剂量转换系数对能谱进行了剂量率转化,与使用长计数器的测量结果进行比较,发现在校准参考位置的剂量率相对偏差≤20%。开展了聚乙烯慢化同位素中子源获得特定能谱的实验研究,进行了慢化谱的模拟计算和实验测量,两者结果符合较好。该工作为后续的中子计量测试和中子防护材料测试提供了可用的中子参考辐射场。 相似文献
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中国散裂中子源(CSNS)中子辐射剂量监测器可以直接测量人体细胞组织的吸收剂量以及剂量当量,比其他测量方法更适合评估物体在辐射场中的辐射效应。本文分析了影响CSNS中子辐射剂量监测器的电荷灵敏前置放大电路相关性能指标的重要因素,放大电路的开环增益Ao和等效输入电容Ci,基于折叠沃尔曼电路设计了一套适用于CSNS中子辐射剂量监测器的电荷灵敏前置放大电路,并通过采用恒流源负载、自举电容、多级去耦、低噪声电源等方法以提升电路的上升时间、误差特性、电压稳定性和噪声特性等性能指标。经测试表明该电路可以应用于CSNS中子辐射剂量监测器。 相似文献
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《核电子学与探测技术》2015,(8)
ABE-CYCIAE是一种基于标准AB雷姆仪的扩展型中子雷姆仪,该设备将用于HI-13串列加速器升级工程的中子在线监测。设备采用一根BF3管进行中子探测,使用聚乙烯及掺硼聚乙烯作为主要的慢化材料。通过使用MCNP软件对中子能量响应曲线进行模拟,计算的热中子到100 Me V的中子能量响应能较好的符合ICRP74号报告给出的注量剂量转换曲线。BF3管输出的脉冲信号经过电荷灵敏前置放大器放大,并由50 Hz陷波器除去工频干扰后,送入主放大器和计数器进行成型放大和计数。 相似文献
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介绍了一种新型中子剂量当量仪的电子学系统的设计,该系统由电源电路、放大器电路、脉冲幅度甄别电路和仪器控制电路等部分组成.该系统能够满足该新型中子剂量仪的功能要求,能够实现该新型中子剂量仪的信号采集、结果计算和仪表控制等功能. 相似文献
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电子能量损失符合谱仪的一维位置灵敏探测器的读出系统 总被引:1,自引:1,他引:0
介绍了用于电子能量损失符合谱仪的一维位置灵敏探测器的读出系统。一维位置灵敏探测器可以大大提高谱仪的探测效率。其读出系统包括电荷灵敏前置放大器、主放大器、位置信号采集板和接口电路。使用自己设计的信号源对系统进行了测试,取得了较好结果。 相似文献
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《中国原子能科学研究院年报》2017,(0)
正单球中子谱仪利用单慢化球、位置灵敏探测器的组合实现了多球谱仪的功能。采用~6Li、~7Li玻璃闪烁体实现了n-γ混合辐射场的中子甄别,探测器组件结构如图1所示。~6Li闪烁体对热中子和γ射线均有响应,而~7Li闪烁体对热中子无响应。通过前者与后者探测信号的扣除得到热中子信号,实现n-γ混合辐射场内中子甄别。在n-γ场中对单球中子谱仪使用的探测器组件开展了相应研究,探测器组件测试电路如图2所示,其中主放大器增益为10倍,ADC采集时间为300s,ROI设置为200~1 023道,并通过ADC 相似文献
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Hesham Shahbunder Cheol Ho Pyeon Tsuyoshi Misawa Jae-Yong Lim Seiji Shiroya 《Annals of Nuclear Energy》2010
The neutron multiplication parameters: neutron multiplication M, subcritical multiplication factor ks, external source efficiency φ*, play an important role for numerical assessment and reactor power evaluation of an accelerator-driven system (ADS). Those parameters can be evaluated by using the measured reaction rate distribution in the subcritical system. In this study, the experimental verification of this methodology is performed in various ADS cores; with high-energy (100 MeV) proton–tungsten source in hard and soft neutron spectra cores and 14 MeV D–T neutron source in soft spectrum core. The comparison between measured and calculated multiplication parameters reveals a maximum relative difference in the range of 6.6–13.7% that is attributed to the calculation nuclear libraries uncertainty and accuracy for energies higher than 20 MeV and also dependent on the reaction rate distribution position and count rates. The effects of different core neutron spectra and external neutron sources on the neutron multiplication parameters are discussed. 相似文献
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Masahiro Hino Tatsuro Oda Norifumi L. Yamada Hitoshi Endo Hideki Seto Masaaki Kitaguchi 《Journal of Nuclear Science and Technology》2017,54(11):1223-1232
A neutron guide system for neutron resonance spin echo spectrometers has been constructed at BL06 of the Japan Proton Accelerator Research Complex, Materials and Life Science Experimental Facility. The spectrometers consist of two types of neutron spin echo instruments, a modulated intensity by zero effort instrument (MIEZE) and a neutron resonance spin echo instrument (NRSE), to cover a wide energy range for various sample environments. A neutron beam from the moderator is deflected by supermirror neutron guides, split, and separately guided into the MIEZE and NRSE. The characteristic wavelengths of the neutron guide tube for the MIEZE and NRSE are 2.9 and 4.9 Å, respectively. The cross sections of the exit of the MIEZE and NRSE guides are 15 mm × 50 mm and 30 mm × 50 mm, respectively. The neutronics and shielding design were optimized by using the heavy ion transport code system (PHITS), and the absolute average neutron fluxes at the exits of the MIEZE and NRSE guides are estimated to be 2.7 × 108 and 6.9 × 108 n/cm2/s/MW, respectively. The measured fluxes of the MIEZE and NRSE neutron guides are 0.56 and 0.95 times the calculated values, respectively. 相似文献
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L. Tomlinson 《Atomic Data and Nuclear Data Tables》1973,12(2):179-194
Experimental data on delayed neutron precursors are compiled and evaluated. Where available, the following data are listed for each nuclide: half-life, neutron emission probability, total energy available for beta decay, neutron binding energy of the daughter nucleus, major peaks in the neutron spectrum, methods of identification and production. The literature survey ended in December 1972. 相似文献
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为适应聚变堆的发展和处理高放废物的需要,提出裂变-聚变中子源的概念,它是采用LiD组件放在高通量反应堆中或中国先进研究堆(CARR)重水区中,通过慢中子与6Li(n,a)反应产生2.739 MeV氚离子,它与LiD中的D发生聚变反应,产生聚变中子;随着LiD中氚的快速积累,14 MeV 中子产生的D反冲粒子流与氚发生聚变反应,增长聚变中子产额,使 14 MeV 中子注量率逐渐升高.当氚浓度接近0.5×1022时,D反冲粒子流与氚的聚变反应率的产额接近于1,聚变中子将成倍的增长,类似于连锁反应,使聚变中子产额达到饱和,即t时刻产生氚,都被用于产生聚变反应,形成裂变-聚变中子源.这时的通量非常高,必须在接近饱和前对设定的通量(如3.5×1014n/cm2·s)下逐步降低反应堆功率,如降低CARR 中子注量率,使其在设定的通量下达到饱和,适应聚变堆中子注量率的需求.论述了裂变-聚变中子源的原理,聚变中子产生率,氚的积累速率和浓度,D反冲粒子流和与氚的聚变反应速率,以及其影响因素.在均匀中子场下(即不考虑中子降抑的情况下)计算了外径180 mm、内径100 mm的LiD管道中聚变中子注量率. 相似文献
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Extensive (d, t) and (d, Be) fast neutron sputtering results obtained by Batelle-Northwest are summarized for Nb and Au. The measured sputtering ratios are in the range of 10?5 atoms/fast neutron. These results are compared to other available experimental results and to theoretical estimates. Some implications of fast neutron sputtering for future reactors are summarized. 相似文献
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Common Monte Carlo (MC) codes for neutron transport are usually applied to neutron fields of low density under the assumption that the isotopic composition of the structure materials will not be changed in neutron reactions. This assumption is no longer valid in intense neutron fields, where an appreciable number of nuclei of the structural material may get transformed into other isotopes. Due to this time-dependent isotope- transformation; however, neutrons injected later into the system will see a different cross-section profile than the neutrons injected earlier. 相似文献
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N.V. Kornilov A.B. Kagalenko V.Ya. Baryba V.G. Demenkov S.V. Pupko P.A. Androsenko 《Annals of Nuclear Energy》2000,27(18):1643-1667
The secondary neutron spectra (inelastic, elastic, fission) for 237Np were measured by the neutron time of flight spectrometer of the IPPE at the incident energy range 1–2.5 MeV. The solid tritium target was used as a neutron source. The neptunium oxide (189 g) packed in the low mass stainless steel container was used as a scattering sample. The neutron background due to scattering on the target environment and tritium into the target backing was measured and was calculated with the appropriate model of the neutron source. The data were corrected for neutron background, the scattering on the oxygen and iron nuclei, and the effect of the finite sample size. The fission neutron spectra were measured, evaluated and subtracted from the emission neutron spectra to estimate inelastic neutron spectra and cross-sections. The experimental results were compared with ENDF/B-VI, BROND-2, JENDL-3 neutron data libraries. 相似文献