First Characterization of AC-LGAD Sensors using a Readout ASIC

The development of detectors that provide high resolution in four dimensions has attracted wide-spread interest in the scientific community for several applications in high-energy physics, nuclear physics, medical imaging, mass spectroscopy, as well as quantum information. The Low-Gain Avalanche Diode (LGAD) silicon detector has already shown excellent timing performances, but since fine pixelization of LGADs is difficult to achieve, the AC-coupled LGAD (AC-LGAD) approach was introduced to provide high spatial resolution. In this type of device, the signal is capacitively induced on fine-pitched electrodes placed over an insulator and is shared among multiple electrodes. AC-LGADs are therefore considered as promising candidates for future detectors to provide 4-dimensional measurements with high resolution in both space and time dimensions. AC-LGAD sensors designed and fabricated at the Brookhaven National Laboratory (USA) have been coupled and read-out using a fast-time ASIC prototype, the ATLAS LGAD Timing Integrated Read-Out Chip (ALTIROC) that was developed by Omega/IJCLab (France) for the ATLAS timing detector at the HL-LHC. The response of an AC-LGAD strip sensors to beta particles and IR photons has been measured using the ALTIROC0 ASIC and used to study signal sharing, as well as spatial and time resolution of the AC-LGAD sensor.