Direct Dark Matter searches with LZ detector

有大量的宇宙学和天体物理学证据，不仅支持暗物质的存在，而且表明暗物质构成了我们宇宙的大量质量。尽管如此，关于暗物质的许多事情仍然是未知的，包括暗物质实际上由什么组成。Lux-ZEPLIN(LZ)是一项旨在直接探测暗物质的多探测器实验。特别是观察被认为是暗物质构建块的主要候选者之一的相互作用；WIMPS(弱相互作用的大质量粒子)。高灵敏度的LZ探测器(位于南达科他州)使用一个装有液体氙气的时间投影室(TPC)，目的是探测WIMP-原子核的相互作用。而LZ的外部探测器有助于抑制背景粒子的影响，背景粒子也可能在TPC中产生信号。这个博士项目的重点可以分为三个主要部分。其中第一项是基于硬件的；具体涉及为利物浦的LZ光学校准系统设置测试台，以及优化现场可编程门阵列固件(特别是利用光电二极管板测量光强度)。除了有一个基于硬件的部分，这个项目还将有一个软件元素。这一部分的目的是帮助改善对LZ有用的数据分析和数据质量监控框架的开发的优化和支持。最后，本项目的第三个方面将侧重于物理数据分析。这包括开发优化中子本底识别和抑制的分析程序。以及物理分析框架的开发，利用简化的理论，目的是将LZ的结果与对撞机实验的暗物质搜索结果进行更直接的比较。

There is an abundance of both cosmological and astrophysical evidence, not only to support the existence of Dark Matter, but also to suggest Dark Matter makes up a great quantity of the mass of our universe. Despite this, much about Dark matter remains unknown, including what Dark matter actually consists of. LUX-ZEPLIN (LZ) is a multi-detector experiment that aims to directly detect Dark Matter. Specifically looking to observe interactions from what are considered to be one of the leading candidates for the building blocks of Dark Matter; WIMPS (Weakly Interacting Massive Particles). The highly sensitive LZ detector, (located in South Dakota), uses a Time Projection Chamber (TPC) containing liquid xenon with the aim of detecting WIMP-nucleus interactions. While the LZ's outer detector helps to suppress the effect of background particles which could also potentially produce signals in the TPC.The focus of this PhD project can be split into three main sections. The first of these being hardware based; specifically involving the setup of a test stand for the LZ Optical Calibration System in Liverpool, as well as optimization of FPGA firmware (particularly focusing on measurements of light intensities with photodiode boards). As well as having a hardware-based section, this project will also have a software element to it. The aim of this section being to help improve the optimisation and support in the development of the data analysis and data quality monitoring frameworks useful to LZ.Finally, the third aspect of this project will be focused on the physics data analysis. This includes the development of analysis procedures for optimization of neutron background identification and suppression. As well as the development of physics analysis framework, utilising simplified theories with the aim of this leading towards a more direct comparison of results from LZ to results with Dark Matter search results from collider experiments.