标题： 大钠碘探测器在寻找暗物质中的光产率测定 显示英文标题

标题： Light yield determination in large sodium iodide detectors applied in the search for dark matter

摘要： NaI(Tl)探测器在通过其与靶核的弹性散射搜索银河系暗物质粒子中的应用是有充分理由的，因为DAMA/LIBRA长期以来在年调制方面有高度显著的正结果，仍需要确认。 为了达到这一目标，必须达到非常低的能量阈值（在keV级别或以下）、非常低的放射性本底（在几计数/keV/kg/天），以及高探测质量（在100公斤量级或以上）。 最重要的技术问题之一是优化大质量晶体的晶体固有闪烁光产额以及光收集系统的效率。 在ANAIS（使用NaI闪烁体的年调制）暗物质搜索项目框架下，来自不同供应商的大尺寸NaI(Tl)晶体与两个光电倍增管（PMTs）耦合，并在Canfranc地下实验室进行了测试。 本文介绍了利用外部和内部源发射的伽马射线/电子在非常低能量下的全吸收峰所测得的NaI(Tl)闪烁光收集估计，以及通过使用非常低能量脉冲尾部选择的单光电子事件群体。 对于ANAIS探测器最终设计和选定的供应商，可以报告出闪烁光收集水平达到15~光电子/keV。 考虑到所使用的PMT单元的量子效率，这些NaI(Tl)晶体的固有闪烁光产额在3到25~keV能量沉积范围内高于40~光电子/keV。 ANAIS晶体的这种非常高的光输出允许在1~keV以下触发，这对于提高暗物质直接探测的灵敏度非常重要。 显示英文摘要

摘要： Application of NaI(Tl) detectors in the search for galactic dark matter particles through their elastic scattering off the target nuclei is well motivated because of the long standing DAMA/LIBRA highly significant positive result on annual modulation, still requiring confirmation. For such a goal, it is mandatory to reach very low threshold in energy (at or below the keV level), very low radioactive background (at a few counts/keV/kg/day), and high detection mass (at or above the 100 kg scale). One of the most relevant technical issues is the optimization of the crystal intrinsic scintillation light yield and the efficiency of the light collecting system for large mass crystals. In the frame of the ANAIS (Annual modulation with NaI Scintillators) dark matter search project large NaI(Tl) crystals from different providers coupled to two photomultiplier tubes (PMTs) have been tested at the Canfranc Underground Laboratory. In this paper we present the estimates of the NaI(Tl) scintillation light collected using full-absorption peaks at very low energy from external and internal sources emitting gammas/electrons, and single-photoelectron events populations selected by using very low energy pulses tails. Outstanding scintillation light collection at the level of 15~photoelectrons/keV can be reported for the final design and provider chosen for ANAIS detectors. Taking into account the Quantum Efficiency of the PMT units used, the intrinsic scintillation light yield in these NaI(Tl) crystals is above 40~photoelectrons/keV for energy depositions in the range from 3 up to 25~keV. This very high light output of ANAIS crystals allows triggering below 1~keV, which is very important in order to increase the sensitivity in the direct detection of dark matter.