Muons comprise an important contribution of the natural radiation dose in air (approx. 30 nSv/h of a total dose rate of 65-130 nSv/h), as well as in underground sites even when the flux and relative contribution are significantly reduced. The flux of the muons observed in underground can be used as an estimator for the depth in mwe (meter water equivalent) of the underground site. The water equivalent depth is an important information to devise physics experiments feasible for a specific site. A mobile detector for performing measurements of the muon's flux was developed in IFIN-HH, Bucharest. Consisting of 2 scintillator plates (approx. 0.9 m2) which measure in coincidence, the detector is installed on a van which facilitates measurements at different locations at surface or underground. The detector was used to determine muon fluxes at different sites in Romania. In particular, data were taken and the values of meter water equivalents were assessed for several locations from the salt mine from Slanic Prahova, Romania. The measurements have been performed in 2 different galleries of the Slanic mine at different depths. In order to test the stability of the method, also measure- ments of the muon flux at surface at different elevations were performed. The results were compared with predictions of Monte-Carlo simulations using the CORSIKA and MUSIC codes.
A feasibility study of extruded plastic scintillator embedding WLS fiber for AMoRE-II muon veto
AMoRE-II是高级钼基稀有过程实验的第二阶段，目的是使用约200公斤含氘低温探测器寻找100 Mo同位素的无中微子双β衰变。AMoRE-II需要使用各种方法将本底水平保持在10-5计数/keV/kg/年以下，以最大限度地提高灵敏度。方法之一是在远离宇宙射线背景的地下深处进行实验。AmoRE-II将在Yemilab运行，深度约为1，000米。然而，即使在如此深的地下环境中，仍然存在幸存的宇宙μ子，它们会影响测量，应尽可能排除。μ子否决探测器是必要的，以拒绝μ子诱导的粒子进入内部探测器，其中低温探测器位于。我们已经研究了使用挤出塑料闪烁体和波长漂移光纤与SiPM一起作为μ子否决系统的可能性。我们发现最佳的结构是两层塑料分离器（PS，150 cm x 25 cm x 1.2 cm），每个槽有两个WLS光纤，它可以很好地分离放射性γ，μ子探测效率在99.4%以上。基于700米深地下原型测量的预期通量，我们发现，在Yemilab的AMoRE-II的μ子否决系统的死时间为1 ms否决窗口的0.6%的整个μ子事件。
