液氩探测器的中子伽玛分辨能力测量

Liquid argon is preeminent scintillator, known as high scintillation light yield (~40 photons/keV) and almost the best neutron-gamma discrimination properity (1 neutron from 100 million gammas).Therefore, liquid argon detector can efficiently distinguish signal from background, which is very important for rare event searching, such as dark matter experiment. Furthermore, liquid argon detector can be applied in various purpose, which including liquid argon calorimeter applied in accelerator physics, and modern new physics, such as detecting solar neutrino, supernova neutrino, long baseline neutrino, dark matter and proton decay. Nowadays using liquid argon to build dark matter detector is one of the hottest area in the field of high energy experimental physics. However, liquid argon has not been used for particle detecting experiment in our country. We aimed on measuring the n/gamma discrimination in liquid argon scintillator, which is a most important properity for applying liquid argon as particle detector. Based on mature liquid nitrogen cryocooler technology, gas impurity concentration lower than 0.1ppm technology by adopting domestic Zr hot getter, commercial PMTs as the signal readout device, we can build a movable liquid argon prototype detector. Domestic materials and industry technology will be adopted preferentially to reduce cost and master detector core technology. Neutron beam will be used to measure n/gamma discrimination of the liquid argon detector.

液氩是优秀的闪烁体材料。发光产额为每KeV能量约40光子；液氩探测器应用范围广泛，在加速器实验中早就被用作量能器，而且可以应用在探测太阳中微子、超新星中微子、长基线中微子、暗物质、质子衰变等新物理中。特别是液氩探测器如今已经成为国际热点之一的暗物质实验的重要探测手段。液氩具备约亿倍的中子-伽玛分辨能力，超过了其它闪烁材料，对寻找稀有事例的暗物质探测非常重要。这项探测器技术国内还没有发展起来。 本申请将致力于测量液氩探测器最重要的一个物理性能：中子-伽玛分辨能力。我们将基于国内工业水平来研制可移动的液氩探测器模型用于中子束流实验测量，以期掌握探测器核心技术并降低研制成本。探测器需要的低温技术将建立在我们已经掌握的液氮制冷技术之上，氩气纯化技术将基于国产的锆基吸气剂技术之上，低温的光电倍增管采用商品购买的方式获取。

液氩探测器应用范围广泛，在加速器实验中早就被用作量能器，而且可以应用在探测太阳中微子、超新星中微子、长基线中微子、暗物质、质子衰变等新物理中。特别是液氩探测器如今已经成为国际热点之一的暗物质实验的重要探测手段。液氩是优秀的闪烁体材料。发光产额为每KeV能量约40光子；液氩具备约亿倍的中子-伽玛分辨能力，超过了其它闪烁材料，对寻找稀有事例的暗物质探测非常重要。.通过本课题的研究，已经建立了一个液氩探测器实验室。放射源刻度实验证明，液氩探测器对0.511MeV的伽玛光子的光产额为1.59p.e./keV，达到国际同类实验装置的光产额正常值。这表明我们已经掌握了液氩探测器相关的低温工程技术、超高纯度氩气净化技术，高洁净度探测器安装和低温条件下探测器运行的相关技术等。可以在国内为液氩探测器在粒子物理学的应用提供探测器技术支持。