College of Engineering, Purdue University, W. Lafayette, IN 47907, USA.
Sensors (Basel). 2020 Jan 23;20(3):640. doi: 10.3390/s20030640.
The monitoring of neutron radiation in extreme high ≈10 (#/cm-s) neutron/photon fields and at extremely-low (≈10 #/cm-s) levels poses daunting challenges-important in fields spanning nuclear energy, special nuclear material processing/security, nuclear medicine (e.g., photon-based cancer therapy), and high energy (e.g., dark-matter) research. Variably proportioned (neutron, gammas, X-ray) radiation, spanning 10-10 eV in energy, is omnipresent from ultra-low (Bq) activity levels (e.g., cosmic rays/ bananas), to extreme high (>10 Bq) levels. E.g., in nuclear reactor cores; in spent nuclear fuel bearing nuclear-explosive-relevant safeguard-sensitive isotopes, such as Pu-239; and in cancer therapy accelerators. The corresponding high to low radiation dose range spans a daunting 10:1 spread-alongside ancillary challenges such as high temperatures, pressure, and humidity. Commonly used neutron sensors get readily saturated even in modest (<1 R/h) photon fields; importantly, they are unable to decipher trace neutron radiation relative to 10 times greater gamma radiation. This paper focuses on sensing ultra-low to high neutron radiation in extremely high photon (gamma-X ray) backgrounds. It summarizes the state-of-art compared to the novel tensioned metastable fluid detector (TMFD) sensor technology, which offers physics-based 100% gamma-blind, high (60-95%) intrinsic efficiency for neutron-alpha-fission detection, even under extreme (≈10 R/h) gamma radiation.
极端高 ≈10（#/cm-s）中子/光子场中和极低（≈10 #/cm-s）水平的中子辐射监测带来了巨大的挑战——这些挑战在核能、特殊核材料处理/安全、核医学（如基于光子的癌症治疗）和高能（如暗物质）研究等领域都很重要。能量在 10-10 eV 范围内的不同比例（中子、伽马、X 射线）辐射，从超低（Bq）活度水平（如宇宙射线/香蕉）到极高（>10 Bq）水平都普遍存在。例如，在核反应堆堆芯中；在含有与核爆炸相关的具有保障相关敏感性同位素的乏核燃料中，如 Pu-239；以及在癌症治疗加速器中。相应的高至低辐射剂量范围跨度很大，达到 10:1 的比例——这还伴随着高温、高压和高湿度等辅助挑战。常用的中子传感器甚至在适度的（<1 R/h）光子场中也容易饱和；重要的是，它们无法区分相对于 10 倍以上伽马辐射的痕量中子辐射。本文重点介绍在极高光子（伽马-X 射线）背景下感应超低至高中子辐射的技术。它总结了相对于新型张紧亚稳态流体探测器（TMFD）传感器技术的现状，该技术提供了基于物理的 100%伽马盲、高效率（60-95%），可用于中子-阿尔法-裂变检测，即使在极端（≈10 R/h）伽马辐射下也是如此。
