ATLAS Liquid Argon Calorimeter Phase-II Upgrade: Technical Design Report

This Technical Design Report documents plans to upgrade the Liquid Argon calorimeters’ readout electronics for the ATLAS experiment for operation at the High Luminosity LHC. When the High Luminosity LHC begins operations in 2026 it will be able to reach a peak instantaneous luminosity of $7.5\times 10^{34}$ cm$^{-2}$s$^{-1}$, which corresponds to approximately 200 inelastic proton-proton collisions per beam crossing. The new Liquid Argon readout electronics will be operational for more than ten years, during which time the LHC is expected to deliver 4 000 fb$^{−1}$ of proton-proton collision data. These requirements are a significant challenge in the design of the new readout system. The design, construction and expected performance of the future readout electronics are presented in detail. These include the results of measurements of prototypes and the plans for their mass production. This document also describes the management of the project, its schedule and major milestones. The costs of the new readout electronics and the collaboration that plans to build it are also presented.