Grant: Subatomic Physics Envelope - Project

CERN's Large Hadron Collider (LHC) has the highest direct energy reach of any particle physics facility and Canada's central role in ATLAS keeps us at the forefront of international particle physics. Following the 2012 discovery of the Higgs boson, during the initial phase of operations (Run 1), and a two-year 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. Run 2 saw excellent accelerator performance with design specifications for the collision intensity (luminosity) regularly reaching twice the design value in 2017 and 2018, resulting in a large dataset for physics analysis. While the Higgs discovery was a remarkable achievement, it only scratches the surface of the potential physics reach of ATLAS and the LHC, which were designed 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 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. Phase-1 of these upgrades, in which Canadians are playing leading roles, has been in progress for about the last six years and are currently being installed, in preparation for Run 3, beginning in March 2022. The three-year period covered by this proposal corresponds to the planned duration of Run 3, in which ATLAS is expected to double the size of its high-energy dataset, with current plans for 13.6 TeV collisions. We are simultaneously also preparing for Phase--2 upgrades of the detector that will be necessary for operation at the High-Luminosity LHC starting in 2027. This work had also been in progress for a number of year, with prominent Canadian contributions. Completion of this work on schedule will require a very focused effort over the coming years. The upgrades are an investment in the future of ATLAS, and present an increasingly rare opportunity for students to be involved in the design, construction and testing of new detector components. Over the period covered by this request, the focus will be on continued analysis of the Run-2 dataset, operation of the detector for Run 3, and continued work on the Phase-2 upgrades. Our roles in all these activities will ensure that we reap the benefits of our significant past investments in ATLAS and the LHC, and ensure its future for the next two decades, while training the next generation of Canadian particle physicists. Given this plan, this request is focused on operations, upgrades and physics analysis, as well as computing operations. It includes significant postdoctoral and student support and funding for travel to CERN for expert activities and physics meetings, subsistence for CERN-based personnel, and travel for physics meetings and conferences.