Widening the search for Dark Matter and Physics beyond the Standard Model with direct detection experiments

我们在宇宙中看到的一切都只是它质量的一小部分。我们可以推断出这种神秘的“暗物质”在早期宇宙中的作用，当它允许星系形成时，我们可以观察到它的引力效应，因为它将星系（包括我们自己的星系）保持在一起。然而，我们无法直接看到它，也还没有任何探测来帮助我们了解它的本质。简而言之，我们知道暗物质存在，但我们不知道它是什么！我们所知道的是，粒子物理学的标准模型如此准确地解释了我们所观察到的大部分现象，但它并不能帮助我们--它没有提供符合要求的候选者。对暗物质的探测不仅会告诉我们宇宙的组成，还将打开标准模型之外的物理学之门，揭开我们与更深入地了解宇宙以及我们在宇宙中的位置之间的面纱。探测暗物质的努力是世界性的--它确实是我们这个时代最重要的科学任务之一。将所有证据拼凑起来，我们最好的理论告诉我们，暗物质是由遍布宇宙但很少相互作用的微小粒子组成的--当你现在读到这篇文章的时候，数百万的暗物质粒子正在无害地穿过你。只是偶尔，其中一个可能会从原子核反弹，给它一个微小的能量。观察这种“直接”散射是确定我们已经看到来自我们自己星系的暗物质的唯一方法;诞生于大爆炸并从那时起一直存在。但要想看到如此微小、罕见的信号，需要进行前所未有的实验：大型探测器，对单个原子的反冲敏感，由最纯净的放射性材料制成，深埋在地球表面之下。LUX-ZEPLIN（LZ）将是有史以来直接寻找暗物质的最大、最先进的实验。LZ将于2019年上线，并在S. Dorothy，USA.我是LZ实验的主要研究人员，负责帮助我们设计它的模拟;从标准模型过程中模拟可能掩盖暗物质特征的“背景”水平;并建立实验的科学范围。LZ的灵敏度将是早期实验的10倍以上，其前所未有的规模和超低背景环境将预示着直接搜索的新时代。除了探索大部分剩余的未知领域以寻找最受欢迎的暗物质候选者弱相互作用大质量粒子（WIMP）之外，LZ现在将对一系列同样动机良好的替代（非WIMP）暗物质候选者和标准模型之外的其他物理学具有敏感性和发现潜力。这些搜索的关键是我在建模背景过程，利用LZ可用的整个能量范围内的多个信号通道，以及开发软件来识别来自完全意想不到的物理学的复杂信号方面的专业知识。我将在LZ的WIMP和替代模型搜索中发挥主导作用，以发现突破性的发现。除了物理分析和软件，我还在英国开发了新的硬件能力，采用世界一流的质谱仪测量材料中的痕量放射性。这项技术对于建立任何未来实验都至关重要，这些实验需要确认发现，执行高精度信号测量，或探索WIMP可用的最后一个可用参数空间。这样的实验将对替代模型和超越标准模型的物理学具有令人难以置信的灵敏度，例如无中微子双β衰变。我的质谱研究将满足下一代实验对放射性纯度的严格要求，并为所有科学所依赖的背景模型提供支持。

Everything we can see in the Universe is only a small fraction of its mass. Most of it, an incredible 85%, is 'dark' - and we know remarkably little about it. We can infer the role of this mysterious 'Dark Matter' in the early Universe when it allowed galaxies to form and we can observe its gravitational effects today as it holds the galaxies, including our own, together. Yet we cannot see it directly and have yet to make any detection that helps us understand its nature. Put simply, we know Dark Matter is there, but we do not know what it is! What we do know is that the Standard Model of particle physics that explains so accurately most of what we do observe cannot help us - it provides no candidates that fit the bill. The detection of Dark Matter will not only tell us what much of our Universe is made of, it will also open the door to physics beyond the Standard Model, bringing down the veil between us and a deeper understanding of the Universe and our place within it. The effort to detect Dark Matter is worldwide - it is truly one of the most important scientific missions of our time.Piecing together all the evidence, our best theories tell us Dark Matter is made up of tiny particles that that pervade the Universe but rarely interact - millions of Dark Matter particles are passing harmlessly through you as you read this right now. Just occasionally one of them may bounce off the nucleus of an atom, giving it a tiny kick of energy. Observing such a 'direct' scatter is the only way to be sure that we have seen Dark Matter from our own galaxy; born in the Big Bang and present ever since. But to have any hope of seeing such tiny, rare signals requires experiments like no other: large detectors, sensitive to the recoil of a single atom, constructed from the most radio-pure materials and buried deep under the surface of the Earth.LUX-ZEPLIN (LZ) will be the largest and most advanced experiment ever built in the direct search for Dark Matter. LZ will come online in 2019 and operate for 3 years in a former gold mine turned science laboratory 1.5 km underground in S. Dakota, USA. I am a leading researcher in the LZ experiment, responsible for the simulations that helped us to design it; that model the level of 'background' from Standard Model processes that may mask Dark Matter signatures; and that establish the experiment's science reach. LZ will be over 10 times more sensitive than earlier experiments and its unprecedented scale and ultra-low background environment will herald a new era in direct searches. In addition to exploring the bulk of the remaining uncharted territory in search of Weakly Interacting Massive Particles (WIMPs), the most popular candidate for dark matter, LZ will now have sensitivity and discovery potential to a whole host of equally well-motivated alternative (non-WIMP) Dark Matter candidates and other physics beyond the Standard Model. Key to these searches is my expertise in modelling background processes, in exploiting multiple signal channels across the full energy range available to LZ, and in developing software to recognise complex signals from wholly unexpected physics. I will take leading roles in the WIMP and alternative model searches from LZ to uncover groundbreaking discoveries.Alongside physics analyses and software, I have developed new hardware capability in the UK with world-class mass-spectrometry to measure trace radioactivity in materials. This technique is crucial to building any future experiment needed to confirm discovery, perform high-precision measurements of signal, or explore the last of the available parameter space available for WIMPs. Such an experiment would have incredible sensitivity to the alternative models and beyond Standard Model physics, such as neutrino-less double beta decay. My mass-spectrometry research will meet the stringent radio-purity needs for future generation experiments and feed the background model upon which all the science rests.