Development of the trigger readout system for the phase-I upgrade of the ATLAS Liquid Argon calorimeters

The ATLAS Liquid Argon (LAr) Calorimeters were designed and built to measure electromagnetic and hadronic energy in proton-proton collisions produced at the LHC at centre-of-mass energies up to 14 TeV and at instantaneous luminosities up to 10³⁴cm^-2s^-1. An LHC upgrade is planned to enhance the luminosities to 2-3×10³⁴cm^-2s^-1 and to deliver an integrated luminosity of about 300 fb^-1 during Run 3 from 2021 through 2023. In order to improve the identification performance for electrons, photons, taus, jets, missing energy at high background rejection rates, an improved spatial granularity of the trigger primitives has been proposed. A new trigger readout system is being designed to digitize and process the signals with higher spatial granularity. A demonstrator system has been developed and installed on the ATLAS detector to evaluate the technical and performance aspects. Analog signal parameters including noise and cross-talk have been analyzed. The performance of the new demonstrator system in the data taking run will be presented. The next generation of prototypes for the trigger readout system is being developed. In this paper, research and development of radiation tolerant custom ASICs for the final trigger readout system will be discussed.