Irradiation tests and expected performance of readout electronics of the ATLAS Hadronic Endcap calorimeter for the HL-LHC

The readout electronics of the ATLAS Hadronic Endcap Calorimeter (HEC) will have to withstand an about 3-5 times larger radiation environment at the future high-luminosity LHC (HL-LHC) compared to the LHC design values. The radiation damages of the front-end electronics made in GaAs technology could significantly affect the HEC performance. Recent measurements of characteristics neutron and proton irradiated ASICs at room and LAr temperatures are reported, which allow an improved assessment of the expected degradation in HL-LHC conditions. These measurements are furthermore applied to simulations of the calorimeter performance. Results from replacement technologies, like Si CMOS, are also presented.