共查询到20条相似文献,搜索用时 78 毫秒
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研究了7种煤中主要元素对^241Am—Be中子源在煤中形成中子场的影响.给出了描述中子场中快中子和热中子数量变化曲线的经验公式和拟合参数。 相似文献
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为促进国内煤料瞬发γ中子活化分析(prompt gamma neutron activation analysis, PGNAA)技术开发,本研究使用基于蒙特卡罗模拟方法的MOCA程序对煤料PGNAA技术常用中子源252Cf进行模拟建模,并对252Cf中子源在煤料和常用慢化体聚乙烯中的中子场分布进行模拟计算,得到了源距与中子通量的关系曲线。通过模拟计算的结果,结合煤料PGNAA的测量过程和实验室情况,设计了既可表征大批煤料PGNAA过程又可实现辐射防护的实验装置。使用该装置开展实验室实验,取得了具有明显特征峰的实验谱图和良好线性的灰分标定系数,表明设计的实验装置具有适宜性,可利用该装置对煤料PGNAA进行进一步实验室研究。 相似文献
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为促进国内煤料瞬发γ中子活化分析(prompt gamma neutron activation analysis,PGNAA)技术开发,本研究使用基于蒙特卡罗模拟方法的MOCA程序对煤料PGNAA技术常用中子源252 Cf进行模拟建模,并对252 Cf中子源在煤料和常用慢化体聚乙烯中的中子场分布进行模拟计算,得到了源距与中子通量的关系曲线。通过模拟计算的结果,结合煤料PGNAA的测量过程和实验室情况,设计了既可表征大批煤料PGNAA过程又可实现辐射防护的实验装置。使用该装置开展实验室实验,取得了具有明显特征峰的实验谱图和良好线性的灰分标定系数,表明设计的实验装置具有适宜性,可利用该装置对煤料PGNAA进行进一步实验室研究。 相似文献
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研制成功煤(石油)井补偿中子法测井用的中子闪烁体对——ST1604、ST1605。其中子灵敏物质分别是Φ3、Φ4的多柱型~6Li玻璃闪烁体,对热中子的透射探测效率分别为50—60%和~100%,而对~(60)Coγ射线探测效率<0.3%。此产品也可作其他强γ场中的高灵敏中子探测器。 相似文献
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中子场空间分布特性研究 总被引:1,自引:1,他引:0
采用Monte-Carlo方法,以高斯聚变中子谱和麦克斯韦裂变中子谱为源谱,进行了中子在大气中输运的理论模拟,给出了不同源高度,空问不同位置处的中子注量、能谱和吸收剂量,并总结了中子场的空问分布特性。 相似文献
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本工作利用加拿大多伦多大学的SLOWPOKE-Ⅱ微型核反应堆仪器中子活化分析对21种煤样(15种中国煤和6种加拿大煤)及其相应的煤灰中36种元素进行了测定,研究了各种微量元素在煤燃烧过程中的行为及其对环境的影响。 相似文献
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热中子和共振区的中子在快中子临界装置中所占的份额很小,但是由于其相对大的截面,在慢化物存在的情况下,热中子和共振中子份额的微小变化,对^239Pu裂变室测量中子注量的结果影响很大。通过测量^239Pu裂变电离室在包镉和包硼、周围有无慢化物等情况下的反应率,Au、In活化片的镉比,S活化片在能谱变化下与^239。Pu的反应率比等,分析了快中子临界装置中热中子和共振区中子的分布,讨论了中子能谱变化对^239Pu裂变室测量快中子注量的影响及解决办法。 相似文献
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9Be(d,n)加速器中子源中子照相的研究 总被引:8,自引:2,他引:6
加速器中子源比反应堆中子源更具灵活性,北京大学正在发展基于RFQ加速器的小型中子照相装置.为了更好地设计和优化此装置,实现高品质的中子照相,我们在北京大学4.5 MV静电加速器上建立了中子照相实验平台,包括科学级制冷、高灵敏度、低噪声的CCD数字成像系统,模拟基于厚铍靶9Be(d,n)反应RFQ中子源的条件,并利用此系统开展中子成像技术的研究.实验在像平面热中子注量率为5×103 cm-2·s-1或快中子注量率为3.7×104 cm-2·s-1的情况下获得了一定质量的热中子及快中子照片.当利用RFQ直线加速器强中子源时将可获得更高质量的图片,从而可以满足大多数的应用需要. 相似文献
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Masao Komeda Akira Ohzu Takamasa Mori Yoshiaki Nakatsuka Makoto Maeda Masatoshi Kureta 《Journal of Nuclear Science and Technology》2017,54(11):1233-1239
The neutron multiplication effect appears when an item contains large amounts of nuclear material. The neutron multiplication effect in this paper means the effect of subsequent fission reactions which are caused by fission neutrons produced by interrogation neutrons from a neutron generator. The previous active neutron method could not distinguish between first-fission and subsequent-fission neutrons and might overestimate the amount of nuclear material. However, the neutron multiplication effect in the active neutron method has not been adequately investigated. We discuss the evaluation method of the multiplication effect in the fast neutron direct interrogation method, one of the active neutron methods, using simulations with the Monte Carlo code MVP and experiments involving uranium waste drums. The first-generation neutrons from an external neutron source generate fission neutrons called second-generation neutrons, the second-generation neutrons generate third-generation neutrons, and so on. This study supposes that the neutron multiplication effect is mainly caused by the third-generation neutrons under the condition that the fourth-generation neutrons are much fewer. This paper proposes a correction method for the neutron multiplication effect in the measured data. 相似文献
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作为一个覆盖全球的太阳中子望远镜观测网网点.与羊八井现有的28支NM-64组成的中子监测器联合,在第23太阳活动周对一个伴随X3.3级太阳耀斑可能的中子事件进行了观测。 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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Coal analysis using the pulsed neutron generator 总被引:3,自引:0,他引:3
JING Shi-Wei LIU Lin-Mao GU De-Shan QIAO Shuang SANG Hai-Feng ZHANG Yong-Xiang ZHANG Zhong-Hua CAO Xi-Zheng TIAN Yu-Bing CHI Yan-Tao ZHAO Xin-Hui 《核技术(英文版)》2003,14(4)
A prototype of elemental analyzer for coal has been developed by using a PFTNA (pulse fast thermal neutron analysis) system. The PFTNA technology is based on the reactions such as (n, γ), (n, n'γ), (n, pγ), etc. by examining the characteristic gamma rays emitted. In our prototype a pulsed neutron generator provides 14 MeV pulse neutrons, which contribute to the separation of spectrum II (the sum of capture and activation spectrum) from spectrum I (the sum of inelastic, capture and activation spectrum), and thus to the measurement of C and O contents in coal. Data management is completed by computer program using the least-square regression method. The experiment in Changshan Power Plant for 3 months showed that the precision of calorific value, whole water, volatile content and ash content is 0.5 kJ/kg, 1.0 wt%, 2.0 wt% and 1.5 wt%, respectively. 相似文献
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虚拟仪器技术在D-T靶中子管中子产额测量中的应用 总被引:1,自引:0,他引:1
虚拟仪器是计算机辅助测试(CAT)领域内最具活力的一项技术。介绍了利用虚拟仪器编程语言Labwindows/CVI的强大功能实现中子测试过程中探头标定、信号采集、测量分析和结果处理的一次实践。 相似文献