Development of High Resolution Homogeneous Calorimeter Using Liquid Xenon

在本科研项目中，我们研制了一种高分辨率的均质液态氙量热计，这种新型量热计是以液态氙为激活介质，当γ射线和电子入射时，它会发出紫外闪烁光。围绕在液体氙周围的许多光电倍增管（PMT）测量这些闪烁光。量热计在液体氙体积中不包含任何被动材料（如电极），因此可以充分观察所有的能量沉积。我们主要集中在实现大体积所需的各种技术的开发上（1,000升或3吨的订单）探测器。作为探测器介质的液体氙保证是完全均匀的，然而，一些杂质污染，如果存在，吸收闪烁光并且可能使这种大体积装置的性能恶化。我们成功地开发了一种新的，有效的净化方法，通过循环液体快速去除杂质。 ...更多信息 使用低温离心液体泵通过分子筛来分离氙。我们还发展了氙的转移、氙的压力/温度控制、安全防护等方法和技术，这些都是大体积液体氙探测器实际应用所必需的。在这项测试中，我们收集了光电倍增管的波形数据，并证明我们可以区分入射的γ射线和α粒子。我们还成功地开发了一种新型的光电倍增管与光电阴极和基极电路，可以维持非常高的背景率，即使在低温下。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吻合得很好。雪崩光电二极管（APD）在液体氙中进行了操作和测试。APD非常紧凑，并且具有非常高的量子效率。该测试的成功开辟了广泛的未来应用，如监测吸收长度。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