Speaker
Description
The High-Luminosity phase of the LHC (HL-LHC) will bring an increase in the instantaneous luminosity of the present accelerator by a factor of 7.5, leading up to 200 interactions per bunch crossing. This extreme pile-up environment will be a challenge for the track reconstruction performance of ATLAS, particularly in the forward region. To address this, the High-Granularity Timing Detector (HGTD) will be installed between the new Inner Tracker (ITk) and the calorimeters, covering a pseudorapidity range of 2.4 < |η| < 4.0. It will provide precise timing measurements, with a resolution of 30 ps per track at the beginning of operation and up to 50 ps at the maximum HL-LHC fluence. This allows HGTD to recover the tracking performance in the forward region when combined with the ITk spatial resolution.
HGTD consists of 8032 modules, each composed of two hybrids, and a total of about 3.6M channels. A hybrid integrates a Low-Gain Avalanche Detector (LGAD) sensor bump-bonded to a dedicated front-end ASIC, called the ALTIROC. The readout cells have a size of 1.3 mm x 1.3 mm.
This talk will present recent performance studies of ALTIROC-A modules, the final version of the ASIC, ahead of the (pre-)production phase. The testbench characterization procedure will be described, including threshold tuning and connectivity tests. Results from testbeam campaigns will also be shown, highlighting the measurements of the hit efficiency and the timing performance of the modules.