Towards a 20 ps timing detector with hybrid and CMOS monolithic LGADs for the future ALICE 3 experiment at LHC

In the context of the future ALICE 3 experiment, planned for installation at the CERN-LHC during LS4 in 2034-35, an intensive research program is actively addressing the challenge of identifying a 20-picosecond sensor technology for the Time-Of-Flight detector. Key results and next steps in the development of both traditional and monolithic Low Gain Avalanche Detectors (LGADs and CMOS-LGADs) are presented. Comprehensive studies conducted on progressively thinner LGAD highlighted the potential of a thinner design for improved timing performance, and a resolution below 20 ps was achieved. To address the challenge of a small signal at the input of the front-end electronics, the novel double-LGAD concept was introduced and tested for the first time. Extending the LGAD concept to a CMOS technology has the potential to offer a transformative path forward, combining precise timing and full-area coverage in a monolithic approach, offering a simpler and cost-effective assembly. The first CMOS-LGAD prototypes, produced in the third ARCADIA engineering run using the 110 nm technology of LFoundry, were tested for the first time and the most recent production reached an intrinsic sensor time resolution of 75 ps in line with simulations. Efficiency and in-pixel time resolution are presented together with the first studies on irradiated sensors and next steps towards the 20-ps goal are discussed.