Development of High Resolution Homogeneous Calorimeter Using Liquid Xenon

在这个科研项目中，我们开发了高分辨率的液体氙量热计，这种新型的量热计使用液体氙气作为活性介质，在伽马射线和电子入射时发出紫外光闪烁光。环绕在液体氙气周围的许多光电倍增管(PMT)测量这些闪烁的光。量热计在液体氙气体积中不含任何电极等被动材料，因此可以完全观察到所有的能量沉积。我们主要集中在实现大体积(1000升或3吨级)探测器所需的各种技术的发展。液体氙气作为探测器介质确保了完全均匀，但如果存在一些杂质污染，会吸收闪烁光，并可能恶化如此大体积器件的性能。我们成功地开发了一种新的、高效的净化方法，通过循环液…快速去除杂质使用低温离心液压泵通过分子筛获得更多的id氙气。我们还开发了氙气转移、氙气压力/温度控制、安全措施等方法和技术，这些都是大体积液体氙气探测器实际应用所必需的。我们用π^0衰变测试了液体氙气探测器的性能。在这项试验中，我们收集了PMT的波形数据，并证明了我们可以区分入射伽马射线和α粒子。我们还成功地研制出了一种新型的光电阴极和基极电路的PMT，即使在低温下也能保持非常高的本底速率。开发了计算机程序来模拟探测器的响应，结果表明与观测数据非常吻合。雪崩光电二极管(雪崩光电二极管)在液态氙气中运行和测试。雪崩光电二极管结构紧凑，量子效率很高。这项测试的成功开辟了广泛的未来应用，如监测吸收长度。较少

In this scientific research project we have developed high resolution homogeneous calorimeter using liquid xenon.This new type of calorimeter uses liquid xenon as the active medium that emits UV scintillation lights upon incidence of gamma rays and electrons. A number of photomultiplier tubes (PMTs) surrounding the liquid xenon measure these scintillation lights. The calorimeter does not contain any passive material like electrodes in the liquid xenon volume, thus can fully observe all the energy deposits.We mostly concentrated on developments of various technologies necessary to realize a large volume (an order of 1,000 liters or 3 tons) detector.Liquid xenon as the detector medium is guaranteed to be perfectly uniform, however, some impurity contamination, if it exists, absorbs the scintillation light and could deteriorate the performance of such a large volume device. We successfully developed a new, efficient purification method to remove impurities very quickly by circulating liqu … More id xenon through molecular sieves using a cryogenic centrifugal liquid pump. We also developed methods and techniques for xenon transfer, xenon pressure/temperature control, safety precaution, etc. These are necessary for practical application of a large volume liquid xenon detector.We examined the performance of a liquid xenon detector by using π^0 decays. In this test we collected waveform data of PMTs and proved that we can distinguish incident gamma-rays from alpha particles. We also succeeded in developing a new type of PMTs with photocathode and base circuit that can sustain very high background rates even at low temperatures. Computer codes were developed to simulate the detector response and were shown to agree very well with the observed data.An avalanche photodiode (APD) was operated and tested in liquid xenon. The APD is very compact and has a very high quantum efficiency. The success of this test opened up extensive future applications such as monitoring of absorption length. Less