共查询到18条相似文献,搜索用时 171 毫秒
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介绍了用热释光剂量计进行个人中子剂量监测,对剂量计的刻度,方法作了详细有描述。用Am-Be参考中子辐射场测量了剂量计的线性和响应因子,相对刻度总不确定度为7.6%(K=1)。该剂量计已在辽河油田、江苏油田、华北油田等测井公司应用。 相似文献
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中子准直器在中国散裂中子源(CSNS)的谱仪上起着限制束流截面与发散度的作用,准直器的结构设计中通过在中子飞行管上间隔设置B4C阻挡块可以起到阻挡、吸收屏蔽杂散中子的作用,为此研制了粘结碳化硼中子阻挡块,并对其成型工艺进行了研究,确定了成型最佳粉体尺寸、粘结剂含量和固化温度.对该中子屏蔽材料的中子衰减系数计算结果表明,波长为0.1×10-10、1×10-10和15×10-10m中子通过该材料的线性衰减系数分别为3.42、30.4和449.9 cm-1.力学冲击和热重实验结果也表明该材料符合在CSNS谱仪中子束线屏蔽使用中的性能要求. 相似文献
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检定中子防护剂量仪表的谱中子标准辐射场 总被引:1,自引:0,他引:1
为了满足中子辐射防护剂量仪表检定和个人中子剂量计刻度的需要,我们建立了一个以Am-Be中子源为参考标准的标准中子辐射场。用于定度该场的中子周围剂量当量率,可由下式给出:式中Q是仪器定度参考点位置上的参考辐射场中子人射注量率,h”是中子注量——中子周围剂量当量转换系数,其数值由规程JJG852-93给出。在距源中心为D的参考点处,中子源直接射束导致的中子周围剂量当量率为:式中Q为参考辐射中子源的已知强度,f()为中子源发射率各向异性修正因子,b(D)为空气对中子束的衰减修正因子。本工作在固定的源——探测器距离,… 相似文献
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导出了一个新的中子增殖公式,公式简明,计算量小。经与传统的增殖公式进行比较,后者由于未考虑缓发中子效应,只能用于定性分析。新导出的中子增殖公式较精确地描述了中子的增殖过程,可用于定量计算与分析。 相似文献
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Cihangir Çelik Kenan ÜnlüVijaykrishnan Narayanan Mary J. Irwin 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2011,652(1):370-373
Soft errors are transient errors caused due to excess charge carriers induced primarily by external radiations in the semiconductor devices. Soft error phenomena could be used to detect thermal neutrons with a neutron monitoring/detection system by enhancing soft error occurrences in the memory devices. This way, one can convert all semiconductor memory devices into neutron detection systems. Such a device is being developed at The Pennsylvania State University and named Neutron Intercepting Silicon Chip (NISC). The NISC is envisioning a miniature, power efficient, and active/passive operation neutron sensor/detector system. NISC aims to achieve this goal by introducing 10B-enriched Borophosphosilicate Glass (BPSG) insulation layers in the semiconductor memories. In order to model and analyze the NISC, an analysis tool using Geant4 as the transport and tracking engine is developed for the simulation of the charged particle interactions in the semiconductor memory model, named NISC Soft Error Analysis Tool (NISCSAT). A simple model with 10B-enriched layer on top of the lumped silicon region is developed in order to represent the semiconductor memory node. Soft error probability calculations were performed via the NISCSAT with both single node and array configurations to investigate device scaling by using different node dimensions in the model. Mono-energetic, mono-directional thermal and fast neutrons are used as the neutron sources. Soft error contribution due to the BPSG layer is also investigated with different 10B contents and the results are presented in this paper. 相似文献
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Geoffrey Greene Vince Cianciolo Paul Koehler Richard Allen William Michael Snow Paul Huffman Chris Gould David Bowman Martin Cooper John Doyle 《Journal of research of the National Institute of Standards and Technology》2005,110(3):149-152
The Spallation Neutron Source (SNS), currently under construction at Oak Ridge National Laboratory with an anticipated start-up in early 2006, will provide the most intense pulsed beams of cold neutrons in the world. At a projected power of 1.4 MW, the time averaged fluxes and fluences of the SNS will approach those of high flux reactors. One of the flight paths on the cold, coupled moderator will be devoted to fundamental neutron physics. The fundamental neutron physics beamline is anticipated to include two beam-lines; a broad band cold beam, and a monochromatic beam of 0.89 nm neutrons for ultracold neutron (UCN) experiments. The fundamental neutron physics beamline will be operated as a user facility with experiment selection based on a peer reviewed proposal process. An initial program of five experiments in neutron decay, hadronic weak interaction and time reversal symmetry violation have been proposed. 相似文献
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S. I. Penttila J. D. Bowman 《Journal of research of the National Institute of Standards and Technology》2005,110(3):309-313
The abBA collaboration is developing a new type of field-expansion spectrometer for a measurement of the three correlation coefficients a, A, and B and the shape parameter b. The measurement of A and B requires precision neutron polarimetry. We will polarize a pulsed cold neutron beam from the SNS using a 3He neutron spin filter. The well-known polarizing cross section for n-3He has a 1/v dependence, where v is the neutron velocity, which is used to determine the absolute beam polarization through a time-of-flight (TOF) measurement. We show that by measuring the TOF dependence of A and B, the coefficients and the neutron polarization can be determined with a small loss of the statistical precision and with negligible systematic error. We conclude that it is possible to determine the neutron polarization averaged over a long run in the neutron beta decay experiment with a statistical error less than 10−4. We discuss various sources of systematic uncertainty in the measurement of A and B and conclude that the fractional systematic errors are less than 2 × 10−4. 相似文献
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在中子周围剂量当量仪校准过程中,使用D-D中子源代替传统同位素中子源会使校准过程具有更高的安全性。为推动D-D中子源在中子周围剂量当量仪校准过程中的应用,提出了应用蒙特卡罗(MC)法的能量截断法代替影锥法的散射中子研究方法;分析了在不同类型房间中,不同内部空间尺寸对散射中子的影响。计算结果表明随着房间内部空间的增大,入射探测器的散射中子所占比例会逐渐减小。若使用D-D中子源进行中子周围剂量当量仪校准,在探测距离75cm,探测器直径20cm的情况下,所需的最小正方体房间的内部空间棱长为332cm;所需最小长方体房间的内部空间的长、宽、高分别为410cm、410cm、205cm。 相似文献
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以耐高温型聚酰亚胺为基体,微米碳化硼(B_4C)为热中子吸收剂,采用粉体表面改性及超声湿混-热亚胺化成膜工艺成功制备了一系列B_4CP/PI聚酰亚胺复合薄膜,重点探讨了不同B_4C含量条件下复合薄膜的耐热性能和力学性能以及不同B_4C含量、不同复合薄膜厚度条件下复合材料的热中子屏蔽性能。研究表明:采用上述工艺,B_4C功能粒子在聚酰亚胺基体中可均匀分散;B_4CP/PI复合薄膜的耐热性随B_4C含量的增加显著提高,力学性能则呈相反趋势;所制备的B_4CP/PI复合薄膜表现出优异的热中子屏蔽性能,中子透射率I/I0随复合薄膜厚度增加及B_4C含量增加呈指数变化规律。据此,可通过材料结构设计,满足不同领域对该类耐高温中子防护材料的应用需求。 相似文献
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目的 了解国内外乏燃料运输和储存容器中子屏蔽材料的类型,整理分析现有中子屏蔽材料的性能和特点,为应用于乏燃料运输和储存容器的中子屏蔽材料的研发提供一定参考。方法 综述国内外应用于乏燃料运输和储存容器中子屏蔽材料的应用现状,对关键性能进行总结和比较,并提出其研究重点和发展趋势。结果 目前,硼化不锈钢、碳化硼/铝复合材料、硼铝合金、聚合物基复合材料和屏蔽混凝土等中子屏蔽材料已应用于乏燃料运输和储存容器。结论 随着核电厂高燃耗的发展趋势,未来乏燃料运输和储存容器对中子屏蔽材料的性能提出了更严格的要求,建议注重研发屏蔽性能优异、装配更换方便、耐辐照的中子屏蔽材料。 相似文献
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Passmore C Million M Kirr M Bartz J Akselrod MS Devita A Berard J 《Radiation protection dosimetry》2012,150(2):231-238
A neutron field characterisation was conducted at the AREVA Melox Plant to determine the response of passive and active neutron dosemeters for several stages in the mixed oxide fuel manufacturing process. Landauer Europe provides radiation dosimetry to many contractors working at the Melox site. The studies were conducted to assist in determining the neutron radiation fields the workers are exposed to routinely, evaluate the need for specific neutron correction factors and to ensure that the most accurate neutron dose is reported for the Melox Plant workers. 相似文献