Presler O, Dubinski S, Alfassi Z B
Department of Nuclear Engineering, Ben Gurion University, Beer Sheva 84105, Israel.
Radiat Prot Dosimetry. 2007;126(1-4):244-7. doi: 10.1093/rpd/ncm050. Epub 2007 May 18.
The possibility of localisation of an unknown neutron source in various bulky homogeneous media (box) was studied. Previous study showed that for the planar case, neutron source could be localised with accuracy better than 7%, by using the count rates ratio of two (3)He detectors, positioned on the opposite faces of the box. The influence of the deviation of the source from the virtual plane connecting the two (3)He detectors was studied. It was found that for detectors placed on the centres of the sample faces, larger distance of the source from the central line leads to larger error, up to 15%. It was found that while using the measurement of the ratio R(0) of external source placed on the box face coplanar with unknown source, accuracy does not depend on the distance from central line. Different ways to determine the plane of the unknown source were investigated. It was found that it is impossible to determine it by looking for maximum count rate of one detector or geometric mean of a pair of detectors. The experimental results were confirmed with Monte-Carlo N-particle (MCNP) simulations.
研究了在各种大型均匀介质（箱体）中定位未知中子源的可能性。先前的研究表明，对于平面情况，通过使用位于箱体相对面上的两个³He探测器的计数率比，中子源能够以优于7%的精度定位。研究了源偏离连接两个³He探测器的虚拟平面的影响。结果发现，对于放置在样品面中心的探测器，源离中心线的距离越大，误差就越大，可达15%。结果发现，在使用与未知源共面放置在箱面上的外部源的比率R(0)测量时，精度不取决于离中心线的距离。研究了确定未知源平面的不同方法。结果发现，通过寻找一个探测器的最大计数率或一对探测器的几何平均值来确定它是不可能的。实验结果通过蒙特卡罗N粒子（MCNP）模拟得到了证实。
