Birmingham Experimental Particle Physics Consolidated Grant 2022-25

粒子物理学是一门吸引公众想象力的学科，当有重大发现时，比如希格斯玻色子的发现，它就会成为头条新闻。随着欧洲核子研究中心（CERN）大型强子对撞机（LHC）收集的大量数据集以及未来更多数据的前景，我们正处于该领域一个非常激动人心的时刻。伯明翰有一个平衡的实验运行计划，利用LHC在能量和精度方面的全部优势，以及欧洲核子研究中心加速器综合体的其他独特能力。我们研究在这些实验中观察到的粒子碰撞和衰变，目的是确定物质的最终结构和自然力。多年来，我们一直在ATLAS实验中担任高级领导职务。ATLAS旨在探索实验室中最高能量下的丰富粒子物理主题。在实验中每秒发生的10亿次碰撞中，只有一小部分可以被永久记录下来供分析。我们的团队建造、维护和操作了高度复杂的探测器电子设备（触发系统）的主要部分，该系统的任务是选择最有趣的事件，并在碰撞后的百万分之一秒内将数据速率降低1000倍。我们也非常积极地分析结果数据，与一个强大的团队一起研究希格斯玻色子的详细特性，更大质量的顶夸克的产生和衰变，以及弱力和电磁力载体（W和Z玻色子和光子）之间的微妙相互作用。除了ATLAS之外，该小组在研究重夸克衰变方面表现突出，这为新现象提供了互补的灵敏度。在大型强子对撞机中，巨大的美夸克产生率使人们能够接触到极其罕见的衰变，伯明翰的特色是美重子（类似于质子和中子的三个夸克的组合）的衰变。我们的NA62小组研究的是含有被称为介子的奇怪夸克的粒子，包括超罕见的介子衰变为一个介子和两个中微子，这种情况每100亿次衰变中只发生一次。利用到目前为止获得的数据，我们报告了迄今为止对这种衰变最令人信服的观察结果，并将在未来进一步研究它，利用它对新物理学的特殊敏感性。在未来20年里，大型强子对撞机仍将是粒子物理领域的能量前沿设备。一项雄心勃勃的升级加速器和探测器的计划正在进行中。升级后的每一年（从2027年开始）将提供与十年前相同数量的碰撞，提供巨大的新发现潜力，但也创造了一个非常具有挑战性的实验环境。对于ATLAS，我们在构建一个更强的抗辐射和更高性能的跟踪探测器和一个升级的触发器以处理十倍大的数据速率方面发挥着重要作用。我们的LHCb和NA62团队也在为同一时代的未来阶段进行升级。该小组在粒子物理的非对撞机领域有各种快速发展的兴趣。其中包括NEWS-G实验，我们正在开发一种新型的球形气体探测器，在一个尚未被充分探索的暗物质质量区域寻找神秘的暗物质粒子。它们还包括DUNE的准备工作，这是迄今为止研究难以捉摸的中微子粒子的规模最大的实验；我们正在转移我们在ATLAS上开发的电子专业知识，为DUNE数据收集做出贡献。我们正在积极筹备下一代对撞机设施，在计划碰撞所有电子和质子组合的项目中发挥领导作用，并对所需的探测器进行研发，包括对精确计时测量的兴趣日益浓厚。在我们研发的另一个方面，我们正在将粒子物理学中开发的探测器应用于新的医疗技术，如强子束治疗。

Particle physics is a subject that captures the public imagination and can become headline news when major discoveries take place, such as that of the Higgs boson. With a large data set already collected at the CERN Large Hadron Collider (LHC) and the prospect of much more in the future, we are at a very exciting moment in the field. Birmingham has a balanced programme of running experiments, exploiting the full reach of the LHC in both energy and precision, as well as other aspects of the unique capabilities of the CERN accelerator complex. We study the particle collisions and decays observed in these experiments with the aim of determining the ultimate structure of matter and the forces of nature.We have held senior leadership positions in the ATLAS experiment over the years. ATLAS is designed to explore a wealth of particle physics topics at the highest energies ever reached in the laboratory. Of the billion collisions taking place in the experiment per second, only a tiny fraction can be recorded permanently for analysis. Our group built, maintains and operates a major part of the highly sophisticated on-detector electronics (trigger system) which has the task of selecting the most interesting events and reducing the data rate by a factor of 1000 within two millionths of a second after collisions. We are also very active in analysing the resulting data, with a strong team working on the detailed properties of the Higgs boson, the production and decays of the even more massive top quark and the subtle interactions between the carriers of the weak and electromagnetic forces (the W and Z bosons and the photon).Beyond ATLAS, the group is prominent in studying the decays of heavy quarks, which offer complementary sensitivity to new phenomena. The huge rates of beauty quark production in LHCb gives access to extremely rare decays, a Birmingham speciality being those of beauty baryons (combinations of three quarks similar to protons and neutrons). Our NA62 group studies particles containing strange quarks called kaons, including the ultra-rare kaon decay to a pion and two neutrinos, which happens only once in every 10 billion decays. Using the data taken so far, we have reported the most convincing observation of this decay so far, and will go on to study it further in future, exploiting its particular sensitivity to new physics.The LHC will remain the energy frontier facility in particle physics for a further two decades. An ambitious programme to upgrade both accelerator and detectors is underway. Every year after the upgrade (from 2027) will deliver the same number of collisions as ten years before, offering enormous new discovery potential, but also creating a very challenging experimental environment. For ATLAS, we are playing a major role in the construction of a much more radiation-hard and higher performance tracking detector and an upgraded trigger to handle the ten times larger data rate. Our LHCb and NA62 teams are also working on upgrades for future phases in the same era.The group has various fast-developing interests in non-collider areas of particle physics. These include the NEWS-G experiment, where we are developing novel spherical gas detectors to search for mysterious dark matter particles in a region of their mass that is not yet well explored. They also include preparations for DUNE, the largest-scale experiment ever to study the elusive neutrino particles; we are transferring our electronics expertise developed on ATLAS to contribute to DUNE data colection.We are active in preparations for next generation collider facilities, taking leadership roles in projects that plan to collide all combinations of electrons and protons and performing R&D into the detectors that will be required, including a growing interest in precision timing measurements. In another strand of our R&D, we are applying detectors developed in particle physics to new medical techniques such as hadron beam therapy.