Upgrades to the ATLAS Detector at the Large Hadron Collider

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The funds requested here are in support of R&D efforts targeted at upgrades of the ATLAS detectorat the Large Hadron Collider (LHC) at CERN, to ensure that the performance of the detector is maintainedinto the so-called High Luminosity LHC (HL-LHC) phase, when the luminosity (related to the beam intensityand collision rate) will be up to 7.5 times that for which the LHC and ATLAS were originally designed.The future LHC program has been affirmed as the top priority of European particle physics, and the future ofLHC and ATLAS operations is secure. The ATLAS detector requires upgrades to operate at the increased rates expected at the HL-LHC, and maintaining Canadian involvement in ATLAS includes significant Canadianparticipation in this upgrade program.Collisions at the HL-LHC will result in a larger number of particles in ATLAS, with a corresponding increases in the amount of energy deposited. ATLAS was not designed for this environment, and some parts of it willneed to be upgraded. The Inner Detector, which tracks the trajectories of charged particles, will need to entirely replaced. The new detector, called the ITk, will be built entirely of silicon detector modules.This will be an enormous effort, requiring the involvement of about half of the ATLAS institutes.The Liquid Argon Calorimeter, where the bulk of the Canadian contributions to the original detector weremade, will also need some upgrades. The readout electronics will need to be entirely replaced. Also, the partof this device which sits closest to the LHC proton beams, the forward calorimeter (FCal), which was partiallybuilt in Canada, will not operate properly at the HL-LHC; a number of options for dealing with this problemare under investigation.The Canadian group proposes to be involved in the construction of the tracker upgrade (ITk) and to contribute to the upgrades of the Liquid Argon Calorimeter readout electronics and to whatever upgrade plan is adopted inthe region of the forward calorimeter. The electronics work would follow on naturally from Phase-I upgrade work that the group is already involved in. Because a decision on the FCal upgrade is not expected until June 2016, very little of the funds requested here are for that part of the work; we anticipate including this in a second RTI request to be submitted in 2016.The bulk of the request is for the purchase of parts (silicon sensors, ASICs, electronics boards) for theconstruction of prototype modules for the ITk, and for equipment necessary for the construction and testingof these modules. This is a necessary step in the “site-validation” process being developed for selectingthe ITk module construction sites. The Canadian group plans to build 1000 of the 20000 modules needed forthe “Strips” portion of this detector. For site qualification, funds are requested here for the productionof 20 prototype modules at each of two proposed Canadian sites (Toronto, Vancouver).