Ambient radiation background contributed by the penetrating cosmic ray particles and the radionuclides present in the rock materials have been measured at an underground laboratory located inside a mine at 555 m depth. The laboratory is being set up to explore rare event search processes, such as direct dark matter search, neutrinoless double beta decay, axion search, supernova neutrino detection, etc., that require specific knowledge of the nature and extent of the radiation environment in order to assess the sensitivity reach and also to plan for its reduction for the targeted experiment. The gamma ray background, which is mostly contributed by the primordial radionuclides and their decay chain products, have been measured inside the laboratory and found to be dominated by rock radioactivity for $E_γ\lesssim 3 \,{\rm MeV}$. Shielding of these residual gamma rays for the experiment was also evaluated. The cosmic muon flux, measured inside the laboratory using large area plastic scintillator telescope, was found to be: $(2.051 \pm 0.142 \pm 0.009) \times 10^{-7}\, {\rm cm}^{-2}.{\rm sec}^{-1}$, which agrees reasonably well with simulation results. The neutron background flux has been measured for the radiogenic neutrons and found to be: $(1.61 \pm 0.03) \times 10^{-4} \, {\rm cm}^{-2}.{\rm sec}^{-1}$ for no threshold cut. Detailed GEANT4 simulation for the radiogenic neutrons and the cosmogenic neutrons have been carried out. Effects of multiple scattering of both the types of neutrons within the surrounding rock and the cavern walls were studied and the results for the radiogenic neutrons are found to be in reasonable agreement with experimental results. Neutron fluxes contributed by those neutrons of cosmogenic origin have been reported as function of the energy threshold.
Background Measurements in the Gran Sasso Underground Laboratory
在意大利Gran Sasso国家实验室（LNGS），使用直径为3”的NaI（Tl）探测器在不同的地下位置测量了3000 keV以下的伽马本底通量：A厅、B厅、干涉仪隧道和大体积探测器（LVD）内部。前三个位置的积分通量为0.3- 0.4 s $^{-1}$ cm $^{-2}$，在LVD内部低两个数量级。借助于对每个位置的蒙特卡罗模拟，确定了单个原始同位素对本底的贡献。用直径为11”的NaI（Tl）探测器估算了LNGS干涉仪隧道中的本底中子通量。在不确定度范围内，结果与主厅的其他中子测量结果一致。
Low X-ray bakground measurements at the Underground Canfranc Laboratory
Micromegas探测器由于具有良好的空间和时间分辨能力，是稀有事件搜索实验的良好候选者。最近的X射线的背景水平，这些探测器在CAST实验中实现了进一步的研究，在测量的背景水平的性质。特别是，不同的屏蔽配置已在Canfranc地下实验室进行了测试，使用微散装型探测器，这是以前运行在CAST实验。地下的第一个结果表明，这种技术是由低辐射材料制成的，在适当的屏蔽下，能够达到高达$2 \times 10^{-7}$ keV $^{-1}$ s $^{-1}$ cm $^{-2}$的背景水平。此外，Geant 4模拟补充了实验背景测量，可以了解背景的起源，并优化未来的屏蔽设置。
