Performance Evaluation of the Timing Resolution of an AC-LGADs Bonded to a Si-Ge BJT ASICs

Reconstructing particle tracks in future high-luminosity collider experiments is expected to be challenging due to the huge pile-up tracks. 4D tracking by the inner tracking detectors with both spatial and timing resolution will provide reliable track reconstruction. Capacitive Coupled Low Gain Avalanche Diodes (AC-LGADs) developed by KEK, Tsukuba group with Hamamatsu Photonics K.K. have an excellent timing resolution (∼20 ps) with 20 µm active thickness as well as a 100 µm×100 µm pitch pixelated electrodes to achieve O(10 µm) spatial resolution. To read out the pixelated AC-LGAD sensors without degrading timing performance low noise and low power consumption ASIC is required. In this study, as a possible candidate of AC-LGADs read out ASIC, a silicon-germanium (Si-Ge) based ASIC, featuring low power consumption, low noise, and high-speed operation has been tested. In this paper, the timing resolution of Si-Ge ASIC bonded to the AC-LGAD sensors by wirebonds and flip-chip is evaluated by using a IR laser and a 3 GeV electron beam at KEK, Japan.