Upgrade of the ATLAS detector at the LHC (2023-26)

粒子物理学是一个研究驱动的领域，致力于确定宇宙中最基本的粒子，以及它们如何通过基本力相互作用。位于瑞士日内瓦的欧洲粒子物理实验室(CERN)的大型强子对撞机(LHC)是当今粒子物理研究的前沿实验设备。2012年，在大型强子对撞机上发现了希格斯粒子，这是近几十年来科学上的重大进步之一。大型强子对撞机被用来在非常高的能量下产生质子-质子碰撞，这是由非常大的尖端粒子探测器记录下来的。ATLAS探测器就是大型强子对撞机上的一个这样的探测器系统。自ATLAS项目开始以来，英国一直有参与该项目的长期记录，包括原始探测器的设计和建造，以及利用收集的数据来促进我们对基本粒子和相互作用的基本理解。ATLAS实验利用了一个广泛的物理计划，从在最高质量尺度上搜索新粒子，到进行精确测量来表征和建立标准模型(粒子物理学的理论模型)的参数，并潜在地发现与其预测的偏差。推动这一科学案例的目的是阐明和表征希格斯扇区和在TeV尺度上的电弱对称破坏的性质，并将对新现象的搜索--或者描述它们的特征--扩展到更高质量尺度和更罕见的过程，并辅之以提高测量范围的精度。为了实现这些科学目标，计划了一项光度升级计划，该计划将使大型强子对撞机保持在粒子物理的高能前沿到本世纪40年代，提供的数据集比大型强子对撞机预计在2025年其当前运行阶段结束之前产生的数据集大10倍以上。这项提议的主要目标是完成正在进行的ATLAS探测器的重大升级。更具体地说，正在寻求的资金是为了英国对所谓的ATLAS“第二阶段”升级的贡献，该升级将由15家机构组成的财团提供。探测器、触发器和数据采集升级对于能够收集和充分利用大型强子对撞机从2029年起在其高光度阶段(HL-LHC)向ATLAS提供的大幅增加的数据速率至关重要。除了完成第二阶段升级所需的资源外，这项提议还包括为欧洲核子研究中心升级系统的后续集成和调试提供资源的请求。必要的工作方案(施工、整合和调试)从2023年4月开始，为期六年，本提案中有详细说明。然而，这里提出的资源申请仅针对该计划的头三年，完成之前的资金将在随后的时间内寻求。英国对ATLAS探测器第二阶段升级的责任和交付内容包括以下系统：新的全硅内跟踪器、基于硬件的热量计触发器、事件过滤软件触发器系统、数据采集系统以及实验的计算和软件的开发。ATLAS实验的结果将发表在科学期刊、国家和国际会议上，并通过其他出版物和活动向包括学校在内的更广泛的公众传达。这些科学成果将使世界各地的实验和理论粒子物理学研究人员受益。其他学术受益者包括使用粒子加速器、探测器、先进电子学、软件和计算的其他学科的研究人员。

Particle physics is a research-driven area concerned with establishing what are the most elementary particles in the Universe and how they interact with one another via fundamental forces. The Large Hadron Collider (LHC) at CERN (the European Laboratory for Particle Physics in Geneva, Switzerland) is an experimental facility at the forefront of particle physics research today. The discovery, in 2012, of the Higgs particle at the LHC was one of the major advances in science in recent decades. The LHC is used to produce proton-proton collisions at very high energy, which are recorded by very large cutting-edge particle detectors. The ATLAS detector is one such detector system at the LHC. The UK has a long-standing track record of involvement in the ATLAS project, since its inception, covering the design and construction of the original detector, as well as the exploitation of the data collected to progress our fundamental understanding of elementary particles and interactions. The ATLAS experiment exploits a broad physics programme ranging from searches for new particles at the highest mass scales to making precision measurements to characterise, and establish the parameters of, the Standard Model (the theoretical model of particle physics), and potentially discovering deviations from its predictions.The science case is driven by the aims of elucidating and characterising the nature of the Higgs sector and of electroweak symmetry breaking at the TeV scale, and extending searches for new phenomena - or characterising them if already discovered - to higher mass scales and rarer processes, complemented by improved precision in a range of measurements. To achieve these science goals, a programme of luminosity upgrades is planned which will maintain the LHC at the high energy frontier of particle physics into the 2040s, delivering a dataset more than 10 times larger than that which the LHC is expected to produce until the end of its current phase of operation, in 2025.The main objective of this proposal is to complete major ongoing upgrades of the ATLAS detector. More specifically, the funding being sought is for the UK's contributions to so-called "Phase-II" upgrades of ATLAS, to be delivered by a consortium of 15 institutions. The detector, trigger and data acquisition upgrades are essential to be able to collect and fully exploit the much-increased data rate that the LHC will deliver to ATLAS during its High-Luminosity phase (HL-LHC), from 2029 onwards.In addition to the required resources to complete the Construction of the Phase-II upgrades, this proposal also includes a request of resource for the subsequent Integration & Commissioning of the upgraded systems at CERN. The necessary programme of work (for Construction, Integration and Commissioning) extends for six years, starting in April 2023, and is detailed in the present proposal. The request for resources presented here is, however, only for the first three years of the programme, with the funding to completion to be sought at a subsequent time.The UK responsibilities and deliverables for the ATLAS detector Phase-II Upgrades are in the following systems: the new all-silicon Inner Tracker, the hardware-based calorimeter trigger, the Event Filter software trigger system, the Data Acquisition system and the development of the experiment's Computing and Software.Results arising from the ATLAS experiment will be published in scientific journals, at national and international conferences and, through other publications and events, communicated to the wider public, including schools. The scientific results will benefit the world-wide community of researchers in both experimental and theoretical particle physics. Other academic beneficiaries include researchers in other disciplines using particle accelerators, detectors, advanced electronics, software and computing.