Vagelis Gkougkousis - A High Granularity Timing Detector for the Phase II Upgrade of the ATLAS experiment

Wednesday 18 Oct 2017, 13:00 → 14:00 Europe/Madrid

Seminar (IFAE)

Michael Leyton (IFAE), Stefano Terzo (IFAE)

The expected increase of the particle flux at the high luminosity phase of the LHC (HL-LHC) with instantaneous luminosities up to L ≃ 7.5×1034 cm−2s−1 will have a severe impact on pile-up, expected to reach on average 200 interactions per bunch crossing. Reconstruction and trigger performance of electrons, photons, jets and transverse missing energy is expected to be severely degraded especially in the end-cap and forward region. This region is particularly interesting relevant for physics processes including forward jets, like vector-boson fusion and vector-boson scattering processes, and for physics signatures with large missing transverse energy. A High Granular Timing Detector (HGTD) is proposed in front of the liquid Argon end-cap calorimeters for pile-up mitigation covering the pseudo-rapidity range of 2.4 to about 4.2. Four layers of Silicon sensors are foreseen to provide precision timing information for charged and neutral particles with a time resolution of the order of 50 pico-seconds per readout cell allowing to assign the energy deposits in the calorimeter to different proton-proton collision vertices. Readout cells have transverse sizes of a few mm, resulting to a highly granular detector with several hundred thousand readout channels. Proposed sensor technology is based on Low Gain Avalanche Diode (LGAD) sensors, proven to provide excellent timing resolution in the order of 30psec per layer in single die configuration. The proposed detector layout and Front End readout, laboratory and beam test characterization of sensors and the results of radiation tests are presented.