arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2005.05498physics.ins-dethep-ex
收藏

下一代CDEX实验的现场gamma-ray背景测量

In-situ gamma-ray background measurements for next generation CDEX experiment in the China Jinping Underground Laboratory

H. Ma, Z. She, W. H. Zeng, Z. Zeng, M. K. Jing, Q. Yue, J. P. Cheng, J. L. Li, H. Zhang

摘要:

在中国锦屏地下实验室二期(CJPL-II)C厅使用便携式高纯锗谱仪进行了现场$γ$ -射线测量,以测量低于3 MeV的环境放射性背景,并为下一代中国暗物质实验(CDEX)提供环境$γ$ -射线背景参数。在60 ~ 2700 keV的能量范围内,积分计数率为46.8 cps。通过数值计算和蒙特卡罗模拟分别得到了该光谱仪对混凝土墙和周围空气的探测效率。经计算,Hall-C中墙壁的放射性浓度为${6.8\pm1.5}$ Bq/kg(${^{238}}$ U)、${5.4\pm0.6}$ Bq/kg(${^{232}}$ Th)和${81.9\pm14.4}$ Bq/kg(${^{40}}$ K)。根据测量结果,这些原始放射性核素的未来CDEX实验的预期背景率进行了模拟的单位计数每千电子伏每吨每年(cpkty)的能量范围为2至4千电子伏和2兆电子伏左右。处于长期平衡的具有衰变产物的原始放射性核素的总本底水平分别是能量范围为2 keV至4 keV和约2 MeV的${7.0 \times 10^{-2}}$和${3.1 \times 10^{-3}}$ cpkty。

英文摘要:

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.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑