Characterization of the first full-size production for ePIC TOF layers

Abstract

Low-Gain Avalanche Detectors (LGADs) are characterized by a fast rise time (500 ps) and extremely good time resolution (down to 17 ps). The intrinsic low granularity of LGADs and the large power consumption of readout chips for precise timing are problematic in near-future experiments such as e+e- Higgs factories (FCC-ee) and the ePIC detector at the Electron-Ion Collider. AC-coupled LGADs, where the readout metal is AC-coupled through an insulating oxide layer, could solve both issues at the same time thanks to the 100% fill factor and charge-sharing capabilities. Charge sharing between electrodes allows a hit position resolution well below the pitch/$\sqrt12$ of standard segmented detectors. At the same time, it relaxes the channel density and power consumption requirements of readout chips. Extensive laboratory characterization of AC-LGAD devices from the first full-size (up to 3x4 cm) production from HPK for ePIC will be shown in this contribution. Both pixel and strip geometry was produced and tested. This study was conducted within the scope of the ePIC detector time of flight (TOF) layer R&D program at the EIC.