The ATLAS Experiment at the Large Hadron Collider

欧洲核子研究中心的大型强子对撞机（LHC）拥有任何粒子物理设施中最高的直接能量，加拿大在ATLAS合作中的核心作用使我们处于国际粒子物理的前沿。在运行的初始阶段（运行1）发现希格斯玻色子之后，经过两年的关闭期以改进加速器和探测器，大型强子对撞机在2015年春季开始“运行2”后恢复运行，碰撞能量增加到13 TeV。加速器一直运行得非常好，在2016年6月达到并超过了碰撞强度（亮度）的设计规范。虽然希格斯玻色子的发现是一项非凡的成就，但它只是触及了ATLAS和LHC潜在物理范围的表面，它们从一开始就被设计用于探测TeV尺度上的新物理特征，这些特征可以“稳定”真空并解决标准模型的缺陷。充分发挥ATLAS的潜力需要更多的数据和更高的碰撞强度，这意味着需要进一步升级加速器和探测器，以及对ATLAS记录的质子-质子碰撞数据进行复杂的分析。******该提案涵盖的三年期间对应于运行2的最后一年，以及“长关闭2”（LS2）的两年，在此期间，将对LHC进行进一步改进，以增加亮度，并完成ATLAS探测器的“第一阶段”升级，其中加拿大发挥主导作用，将完成并安装。我们也在为探测器的“第二阶段”升级做准备，这将是2026年高亮度LHC运行所必需的。Run 2的完成将提供一个大型的高能数据样本，这将在未来几年形成丰富的科学产出的基础，其形式是寻找超出标准模型的物理，提高对希格斯玻色子的理解，以及对其他标准模型过程的精确测量。第一阶段和第二阶段的升级工作是对ATLAS未来的投资，为学生提供了一个越来越难得的机会，让他们参与到新探测器组件的设计、建造和测试中来。在本提案所涵盖的期间，通过对Run-2数据的分析和ATLAS升级的工作，我们确保我们从过去对ATLAS和LHC的重大投资中获益，并确保其未来二十年的发展，同时培养下一代加拿大粒子物理学家。考虑到操作和LS2活动的时间表，该请求侧重于探测器操作和升级，以及计算操作和物理分析。它包括博士后和学生支持，前往CERN参加专家活动和物理会议的旅行，CERN工作人员的CERN生活津贴，以及参加物理会议和会议的旅行。

CERN's Large Hadron Collider (LHC) has the highest direct energy reach of any particle physics facility, and Canada's central role in the ATLAS collaboration keeps us at the forefront of international particle physics. Following the discovery of the Higgs boson during the initial phase of operations (Run 1) and a two-year long shutdown period for improvements to the accelerator and detector, the LHC resumed operation with the start of "Run 2" in spring 2015, at an increased collision energy of 13 TeV. The accelerator has been running exceptionally well, with the design specifications for the collision intensity (luminosity) met and then surpassed in June 2016. While the discovery of the Higgs boson was a remarkable achievement, it only scratches the surface of the potential physics reach of ATLAS and the LHC, which were designed from the outset to probe for signatures of new physics at the TeV scale that could "stabilize" the vacuum and address deficiencies of the Standard Model. Achieving the full potential of ATLAS requires more data and thus higher collision intensities, implying the need for further accelerator and detector upgrades, along with sophisticated analyses of the proton-proton collision data recorded by ATLAS.******The three-year period covered by this proposal corresponds to the final year of Run 2, and the two years of “Long Shutdown 2” (LS2) during which further improvements will be made to the LHC, to increase the luminosity, and “Phase-1” upgrades of the ATLAS detector, in which Canada plays a leading role, will be completed and installed. We are also preparing for “Phase-2” upgrades of the detector that will be necessary for operation at the High-Luminosity LHC starting in 2026. The completion of Run 2 will provide a large high-energy data sample that will form the basis of a rich scientific output over the coming years, in the form of searches for physics beyond the Standard Model, improved understanding of the Higgs boson, and precision measurements of other Standard Model processes. Work on the Phase-1 and Phase-2 upgrades is an investment in the future of ATLAS, and presents an increasingly rare opportunity for students to be involved in the design, construction and testing of new detector components. For the period covered by this proposal, via work on analysis of the Run-2 data, and work on ATLAS upgrades, we are ensuring that we reap the benefits of our significant past investments in ATLAS and the LHC, and ensuring its future for the next two decades, all while training the next generation of Canadian particle physicists. Given the schedule for operations and LS2 activities, this request is focused on detector operations and upgrades, as well as computing operations and physics analysis. It includes postdoctoral fellow and student support, travel to CERN for expert activities and physics meetings, CERN subsistence for CERN-based personnel, and travel for physics meetings and conferences.