Article title: Intrinsic background radiation of LaBr₃(Ce) detector via coincidence measurements and simulations

通过符合测量和模拟，鉴别LaBr3(Ce)探测器的固有辐射本底

DOI: 10.1007/s41365-020-00812-8

http://www.nst.sinap.ac.cn/newsDetails/112/941/en/

创新性（主要内容）

This study, for the first time, showcased the decoupling activities of thallium-207, polonium-211, polonium-215, francium-223, and actinium-227. It provided a complete picture of the detector’s intrinsic background through the α- and β-decay chain. This resulted from conducting a coincidence measurement using a Clover detector to identify the internal radioactive isotopes of the Ø3”×3” Saint-Gobain B380 detector. The combination of coincidence spectra with Geant4 simulations allowed the determination of accurate lanthanum-138, bismuth-211, radon-219, radium-223, and thorium-227 activities. Therefore, the findings of this study ultimately provided insights into the radioactive contaminants present in the detector and its influences on the detection sensitivity.

为了提升LaBr3(Ce)探测器的使用效率，我们在本项研究中我们通过分析¹³⁸La、²²⁷Ac及其子核的衰变特征伽马射线和α、β射线之间的符合，结合Geant4模拟，提取了LaBr₃(Ce)晶体中¹³⁸La, ²¹¹Bi, ²¹⁹Rn,²²³Ra, ²²⁷Th的活度；通过比较²¹¹Bi,²¹⁹Rn, ²²³Ra,²²⁷Th活度，发现在所测量的晶体中存在长期平衡，并基于此可提取出²⁰⁷Tl,²¹¹Po, ²¹⁵Po, ²²³Fr和 ²²⁷Ac的活度，这一研究有助于我们全面了解该型探测器的固有辐射本底。这一结果来自于我们对Saint-Gobain公司生产的Ø3”×3” B380探测器结合CLOVER高纯锗探测器进行的符合测量。从这个意义上说，本次研究为研究探测器中的辐射物质作用以及其对探测灵敏度的影响提供了依据。

研究背景（主要原因）

The LaBr3(Ce) crystal is a new inorganic scintillator that is ideal for being widely used in environmental monitoring, oil well logging, nuclear safeguards, and medical imaging. Its superior characteristics in terms of density, light output, temperature response, and decay time make it a favorable substitute for the widely used thallium doped sodium iodide (NaI(Tl)) when high performance is required. However, the LaBr3(Ce) detector is also known to have a relatively high intrinsic background radiation due to lanthanum-138 and actinium-227 impurities. As a result, it limits the application of this detector, especially in low-count rate experiments. Therefore, this study is crucial to understand and enhance the performance of the LaBr3(Ce) detector as well as maximize its potential across various fields.

作为一类新型且理想的无机闪烁体，LaBr3(Ce) 晶体广泛应用于环境监测、石油测井、核安全保障、医学成像等领域，其在密度、光输出、温度响应以及衰减时间方面具有良好特性，可替代广泛使用的铊掺杂碘化钠(thallium doped sodium iodide (NaI(Tl)))，满足人们对高性能的需求。但另一方面，LaBr3(Ce) 探测器受lanthanum-138 和 actinium-227等杂质的影响，具有较高的固有辐射本底，应用范围受到限制，特别是在低计数率实验方面。因此，本研究对于了解并提升LaBr3(Ce) 探测器性能、最大激发其在诸多领域的潜能具有重要意义。

SDG影响力（研究意义）

Innovation and technological advancement are known to be the key drivers of growth, whether it involves societal, economic, or environmental well-being. By encouraging new or improved technologies through research and development, as projected in UNSDG 9: Industries, Innovation and Infrastructure, a significant influence on global resource management, international trades, economic development, etc. would be feasible. Hence, the aim of this study, which is to improve the efficiency of the LaBr3(Ce) detector, is a step towards adopting innovation to overcome the limitations of existing technologies. The findings could be used to provide important parameters when laboratory-based systems are employed under open field environment. Thus, it will improve the on-field application of the scintillating material in terms of addressing radioactive contaminations or for medical purposes.

创新与技术进步是实现社会、经济以及环境福利增长的主要驱动因素。通过不断研究和持续开发，发明全新技术、提升已有技术，可为全球资源管理、国际贸易、经济发展等方面带来深远影响，这一点已在联合国可持续发展17个目标中的第9个目标（工业、创新和基础设施）中有所体现。具体来说，开展本项研究的目的，是进一步提升LaBr3(Ce) 探测器的使用效率，借助创新实现对已有技术的突破。此外，在实验室系统应用于旷场环境的背景之下，本项研究中的发现也为行业提供了重要的技术参数，可进一步提升闪烁材料的现场应用，解决辐射物质作用问题，进而满足环境监测、石油测井、核安全保障、医学成像等多方面的需求。