Monte-Carlo based background reduction and shielding optimisation for a large hyper-pure germanium detector
Monte-Carlo based background reduction and shielding optimisation for a large hyper-pure germanium detector
复制标题
基于蒙特卡罗的大型超纯锗探测器的背景降低和屏蔽优化
DOI：
10.1007/s10967-013-2572-1
复制
发表时间：
2013
影响因子：
1.6
通讯作者：
P. Regan
中科院分区：
文献类型：
--
作者：
R. Britton;J. Burnett;A. Davies;P. Regan
超纯锗探测器的辐射屏蔽系统的性能已被表征为地球辐射源，宇宙μ子，X射线荧光和源光子的康普顿散射。几种方法，以减少看到的背景进行了量化，包括增加铅洞的内半径，并增加屏蔽的厚度。发现通过修改所使用的衬垫厚度可以实现荧光X射线减少的实质性改进。将Sn衬垫从1.5 mm增加到2.5 mm将使Pb X射线的屏蔽从95%增加到99.5%。将Cu衬里从1.0 mm减小到0.5 mm，保持了对Sn/Cd X射线的99.5%屏蔽水平，然而，它大大减少了源光子进入检测器的康普顿散射量（该过程被示出为在背景中引起比X射线荧光多一个数量级的事件）。宇宙μ子被发现通过直接相互作用和次级辐射的产生增加了背景辐射的数量。然而，宇宙μ子的贡献被发现产生的影响比地球辐射和康普顿散射光子/荧光源造成的影响小得多。进入探测器室的背景辐射的总水平被发现减少到完整的200毫米的铅屏蔽模拟。
The performance of a radiation shielding system for a hyper-pure germanium detector has been characterised for Terrestrial radiation sources, Cosmic muons, X-ray fluorescence and the Compton scattering of source photons. Several methods to reduce the background seen are quantified, including increasing the inner radius of the Pb cave, and increasing the thickness of the shielding. Substantial improvements in the reduction of fluorescence X-rays are found to be achievable by modifying the liner thicknesses used. Increasing the Sn liner from 1.5 to 2.5 mm will increase the shielding of Pb X-rays from 95 to 99.5 %. Reducing the Cu liner from 1.0 to 0.5 mm maintains a 99.5 % level of shielding for Sn/Cd X-rays, however it greatly reduces the amount of Compton scattering of source photons into the detector (a process that is shown to cause an order of magnitude more events in the background than X-ray fluorescence). Cosmic muons were found to increase the amount of background radiation seen, both through direct interaction and the production of secondary radiation. The Cosmic muon contribution, however, was found to produce a much smaller effect than that caused by Terrestrial radiation and Compton scattered photons/fluorescence from the source. The total level of background radiation entering the detector chamber was found to decrease up to the full 200 mm of Pb shielding simulated.