论文标题
使用新的NAI（TL）晶体封装来改善光收集
Improving the light collection using a new NaI(Tl)crystal encapsulation
论文作者
论文摘要
NAI（TL）晶体在各种稀有事件搜索实验中用作粒子探测器，因为它们具有出色的光发射质量。晶体光的产率通常高，高于每个KEV的10个光电子，并且其发射光谱在400 nm左右达到峰值，这与Bialkali Photocathode Phototlultiplier管的敏感区域非常匹配。但是，由于NAI（TL）晶体是吸湿性的，因此必须采用一种复杂的封装方法，以防止水分化学攻击晶体并从而降解发射。此外，对于许多新现象搜索至关重要的低能量阈值的操作通常受晶体光产率的限制。在这些情况下，较高的光产率可以转化为较低的阈值，从而提高实验灵敏度。在这里，我们描述了一种封装技术的开发，该技术通过将照片传感器直接连接到晶体中，从而简化整体设计，从而最大程度地减少光损失。用该技术封装的NAI（TL）晶体的光产率提高了30％以上，并且已经测量了每个KEV多达22个光电子。因此，可以降低能量阈值，并提高能量分辨率。具有较高光产量的探测器对具有亚基能的事件敏感，并且非常适合低质量的暗物质粒子搜索和中微子核相干散射的测量。
NaI(Tl) crystals are used as particle detectors in a variety of rare-event search experiments because of their superb light-emission quality. The crystal light yield is generally high, above 10 photoelectrons per keV, and its emission spectrum is peaked around 400 nm, which matches well to the sensitive region of bialkali photocathode photomultiplier tubes. However, since NaI(Tl) crystals are hygroscopic, a sophisticated method of encapsulation has to be applied that prevents moisture from chemically attacking the crystal and thereby degrading the emission. In addition, operation with low energy thresholds, which is essential for a number of new phenomenon searches, is usually limited by the crystal light yield; in these cases higher light yields can translate into lower thresholds that improve the experimental sensitivity. Here we describe the development of an encapsulation technique that simplifies the overall design by attaching the photo sensors directly to the crystal so that light losses are minimized. The light yield of a NaI(Tl) crystal encapsulated with this technique was improved by more than 30%, and as many as 22 photoelectrons per keV have been measured. Consequently, the energy threshold can be lowered and the energy resolution improved. Detectors with this higher light yield are sensitive to events with sub-keV energies and well suited for low-mass dark matter particle searches and measurements of neutrino-nucleus coherent scattering.
