Holmlid Leif, Olafsson Sveinn
Atmospheric Science, Department of Chemistry and Molecular Biology, University of Gothenburg, SE-412 96 Göteborg, Sweden.
Faculty of Physical Sciences, University of Iceland, Reykjavik, Iceland.
Rev Sci Instrum. 2015 Aug;86(8):083306. doi: 10.1063/1.4928109.
Muons are conventionally measured by a plastic scintillator-photomultiplier detector. Muons from processes in ultra-dense hydrogen H(0) are detected here by a novel type of converter in front of a photomultiplier. The muon detection yield can be increased relative to that observed with a plastic scintillator by at least a factor of 100, using a converter of metal, semiconductor (Ge), or glass for interaction with the muons penetrating through the metal housing of the detector. This detection process is due to transient formation of excited nuclei by the well-known process of muon capture, giving beta decay. The main experimental results shown here are in the form of beta electron energy spectra detected directly by the photomultiplier. Events which give a high-energy tail in the energy spectra are probably due to gamma photons from the muons. Sharp and intense x-ray peaks from a muonic aluminium converter or housing material are observed. The detection conversion in glass and Ge converters has a time constant of the order of many minutes to reach the final conversion level, while the process in metal converters is stabilized faster. The time constants are not due to lifetimes of the excited nuclei or neutrons but are due to internal charging in the insulating converter material. Interaction of this charging with the high voltage in the photomultiplier is observed.
传统上，μ子是通过塑料闪烁体 - 光电倍增管探测器来测量的。在此，来自超致密氢H(0)中过程产生的μ子，是由光电倍增管前一种新型转换器进行探测的。使用金属、半导体（锗）或玻璃制成的转换器，使其与穿透探测器金属外壳的μ子相互作用，相对于使用塑料闪烁体所观测到的情况，μ子探测产额可提高至少100倍。这种探测过程是由于通过众所周知的μ子俘获过程形成激发核，进而产生β衰变。此处展示的主要实验结果是以光电倍增管直接探测到的β电子能谱形式呈现的。能谱中出现高能尾部的事件可能是由μ子产生的γ光子导致的。观测到了来自μ子化铝转换器或外壳材料的尖锐且强烈的X射线峰。玻璃和锗转换器中的探测转换达到最终转换水平的时间常数约为几分钟，而金属转换器中的过程稳定得更快。这些时间常数并非由激发核或中子的寿命所致，而是由于绝缘转换器材料内部的充电现象。观测到了这种充电与光电倍增管中的高电压之间的相互作用。
