The LUX-ZEPLIN (LZ) radioactivity and cleanliness control programs
The LUX-ZEPLIN (LZ) radioactivity and cleanliness control programs
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DOI：
10.1140/epjc/s10052-020-8420-x
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发表时间：
2020-11-10
影响因子：
4.4
通讯作者：
Zarzhitsky, P.
中科院分区：
文献类型：
--
作者：
Akerib, D. S.;Akerlof, C. W.;Zarzhitsky, P.
LUX-ZEPLIN（LZ）是第二代直接暗物质实验，其自旋无关的WIMP核子散射灵敏度高于1.4 x 10（-48）cm（2），WIMP质量为40 GeV/c（2），曝光时间为1000天。LZ通过结合5.6吨的大基准体积、主动内部和外部否决系统以及使用具有固有低放射性含量的材料的放射性纯结构来实现这种灵敏度。LZ合作组织在六年的时间里进行了广泛的放射性测定活动，为建筑材料的选择提供信息，并为实验背景模型提供输入，以评估任何可能的信号过量。本文介绍了这一运动及其结果。我们提出了沉积在组件表面的灰尘和氡子体的分析，以及通过检测器的构造和组装来保持背景期望所需的清洁度控制。最后，从运动的例子，以突出固定污染物的放射性测定的LZ光电倍增管，质量控制和质量保证程序，通过制造，氡emanationmeasurements ofmajor subsystems，和定制的探测器系统，以测定闪烁体。
LUX-ZEPLIN (LZ) is a second-generation direct dark matter experiment with spin-independent WIMPnucleon scattering sensitivity above 1.4 x 10(-48) cm(2) for a WIMP mass of 40 GeV/c(2) and a 1000 days exposure. LZ achieves this sensitivity through a combination of a large 5.6 t fiducial volume, active inner and outer veto systems, and radio-pure construction using materials with inherently low radioactivity content. The LZ collaboration performed an extensive radioassay campaign over a period of six years to inform material selection for construction and provide an input to the experimental background model against which any possible signal excess may be evaluated. The campaign and its results are described in this paper. We present assays of dust and radon daughters depositing on the surface of components as well as cleanliness controls necessary to maintain background expectations through detector construction and assembly. Finally, examples from the campaign to highlight fixed contaminant radioassays for the LZ photomultiplier tubes, quality control and quality assurance procedures through fabrication, radon emanationmeasurements ofmajor sub-systems, and bespoke detector systems to assay scintillator are presented.