论文标题
下一代CDEX实验的原位伽马射线背景测量中国地下实验室
In-situ gamma-ray background measurements for next generation CDEX experiment in the China Jinping Underground Laboratory
论文作者
论文摘要
在中国Jinping Underground Laboratory（CJPL-II）的第二阶段，使用便携式高纯度驻留光谱仪（CJPL-II）在3 MEV以下的环境放射性背景表征并提供环境$γ$ -ARE-RAY背景参数（Cedex的下一代深色物质实验）（CDEX）。光谱的积分计数速率在60至2700 keV的能量范围内为46.8 cps。分别从数值计算和蒙特卡洛模拟中获得了对应于混凝土壁和周围空气的光谱仪的检测效率。 Hall-C中墙壁的放射性浓度计算为$ {6.8 \ pm1.5} $ bq/kg，对于$ {^{^{238}} $ u，$ {5.4 \ pm0.6} $ bq/kg，for $ {^{232}} $ {^{232}} $ bq/kg/kg/kg， $ {^{40}} $ k。基于测量结果，以每吨每吨计数（CPKTY）的单位（CPKTY）模拟了来自未来CDEX实验的这些原始放射性核素的预期背景速率，其能量范围为2至4 keV，大约2 MEV。具有衰减产物的原始放射性核素的总背景水平为$ {7.0 \ times 10^{ - 2}} $和$ {3.1 \ times 10^{ - 3}} $ cpkty $ cpkty的能量范围为2 kev至4 keV和2 mev，分别为2 kev和2 mev。
In-situ $γ$-ray measurements were performed using a portable high purity germanium spectrometer in Hall-C at the second phase of the China Jinping Underground Laboratory (CJPL-II) to characterise the environmental radioactivity background below 3 MeV and provide ambient $γ$-ray background parameters for next generation of China Dark Matter Experiment (CDEX). The integral count rate of the spectrum was 46.8 cps in the energy range of 60 to 2700 keV. Detection efficiencies of the spectrometer corresponding to concrete walls and surrounding air were obtained from numerical calculation and Monte Carlo simulation, respectively. The radioactivity concentrations of the walls in the Hall-C were calculated to be ${6.8\pm1.5}$ Bq/kg for ${^{238}}$U, ${5.4\pm0.6}$ Bq/kg for ${^{232}}$Th, ${81.9\pm14.4}$ Bq/kg for ${^{40}}$K. Based on the measurement results, the expected background rates from these primordial radionuclides of future CDEX experiment were simulated in unit of counts per keV per ton per year (cpkty) for the energy ranges of 2 to 4 keV and around 2 MeV. The total background level from primordial radionuclides with decay products in secular equilibrium are ${7.0 \times 10^{-2}}$ and ${3.1 \times 10^{-3}}$ cpkty for energy ranges of 2 keV to 4 keV and around 2 MeV, respectively.
