ALTIROC1, a 20 ps time-resolution ASIC prototype for the ATLAS High Granularity Timing Detector (HGTD)

THE high-luminosity phase of CERN’s Large Hadron Collider (HL-LHC) is foreseen to start in 2026 [1] . The expected increase of the pile-up due to the 200 interactions per bunch crossing will have a severe impact on the physics. A High Granularity Timing Detector (HGTD) is proposed in front of the Liquid Argon End-Cap calorimeters for pile-up mitigation at Level-0 trigger level and in the offline reconstruction. Four layers of very thin (50 µm) Low Gain Avalanche Diodes (LGAD), with a transverse size of 1.3 x 1.3 mm 2 , are foreseen to provide precise timing information for charged and neutral particles with a time resolution of about 30 pico-seconds per MIP.