LIBPhys, Physics Department, University of Coimbra, P-3004-516 Coimbra, Portugal.
Institute for Particle Physics, ETH Zurich, 8093 Zurich, Switzerland.
Sci Rep. 2017 Feb 9;7:41699. doi: 10.1038/srep41699.
The high neutron detection efficiency, good gamma-ray discrimination and non-toxicity of He made of proportional counters filled with this gas the obvious choice for neutron detection, particularly in radiation portal monitors (RPM), used to control the illicit transport of nuclear material, of which neutron detectors are key components. He is very rare and during the last decade this gas has become increasingly difficult to acquire. With the exception of BF, which is toxic, no other gas can be used for neutron detection in proportional counters. We present an alternative where the He atoms are replaced by nanoparticles made of another neutron sensitive material, B. The particles are dispersed in a gaseous volume, forming an aerosol with neutron sensitive properties. A proportional counter filled with such aerosol was exposed to a thermal neutron beam and the recorded response indicates that the neutrons have interacted with the particles in the aerosol. This original technique, which transforms a standard proportional gas mixture into a neutron sensitive aerosol, is a breakthrough in the field of radiation detection and has the potential to become an alternative to the use of He in proportional counters.
正比计数器中填充这种气体的氦具有高中子探测效率、良好的伽马射线甄别能力和无毒特性，是中子探测的明显选择，特别是在辐射门监测器（RPM）中，RPM 用于控制核材料的非法运输，而中子探测器是其关键组成部分。氦非常稀有，在过去十年中，这种气体越来越难以获得。除了有毒的 BF 之外，没有其他气体可用于正比计数器中的中子探测。我们提出了一种替代方案，即用另一种对中子敏感的材料 B 制成的纳米颗粒来替代氦原子。这些颗粒分散在气体体积中，形成具有中子敏感特性的气溶胶。一个填充这种气溶胶的正比计数器暴露在热中子束下，记录的响应表明中子与气溶胶中的颗粒发生了相互作用。这种将标准正比气体混合物转化为中子敏感气溶胶的新技术是辐射探测领域的一项突破，有可能成为替代正比计数器中使用氦的方法。
