Environmental gamma background measurements in China Jinping Underground Laboratory

Search of low-mass WIMPs with ap-type point contact germanium detector in the CDEX-1 experiment

“…The flux of cosmic ray and associated backgrounds is down to 61.7 y −1 ·m −2 [13]. In addition, the radioactivities of 232 Th, 238 U and 40 K from rock surrounded CJPL were very low based on in situ measurement [14]. The low cosmic-ray flux and radioactivities of 238 U and 232 Th give rise to low level of neutron flux.…”

Characterisation of the natural gamma-ray background in the underground Callio Lab facility

“…6 and Table 2) clearly depend on the efficiency of detection of the HPGe detector and the quality of protection. Typically, the integral background count rate in the energy range from 40 keV to 2.7 MeV normalised to the HPGe crystal mass is used to compare data collected using different detectors [11,16]. In…”

“…Numerous experiments [7,16,18,19] have shown that the gamma-ray background in underground laboratories depends on the level of radon in the air. Radon penetrates into all parts of the equipment, resulting in worse background characteristics.…”

The China Jinping Underground Laboratory and Its Early Science

“…Owing to the large rock overburden, the attenuation factor of 10 −8 relative to the typical cosmic-ray fluxes on the surface is the largest of all operational underground laboratories ( Figure 2). [12] Plastic scintillator telescope (2.0 ± 0.4) × 10 −10 cm −2 s −1 Radioactivity of bedrock [58] In The γ radioactivity from the bedrock, as well as the concrete components of CJPL-I, were measured with a in situ high-purity germanium detector (Table II) [58]. The bedrock of Jinping Mountain is mainly marble, providing relatively good radiopurity.…”