First results of CROSS underground measurements with massive bolometers

CROSS (Cryogenic Rare-event Observatory with Surface Sensitivity) project is focused on 0$\nu$2$\beta$ decay searches with surface-sensitive bolometers, aiming to develop a mid-scale demonstrator with Li$_2^{100}$MoO$_4$ bolometers and Al coating, which allows rejecting near-surface events thanks to pulse shape modification, induced by the superconducting film. Several bolometers were installed in 2019 with the goal to verify the required performance for CROSS needs. Li$_2$MoO$_4$ crystals and Ge light detectors, instrumented with NTD sensors, were measured over 5 months with $\sim$90% duty cycle. A study of pulse shape discrimination with 0.2 $\mu$m Al coating on the lateral side of Li$_2$MoO$_4$ cylindrical crystal (mass $\sim$210 g) is performed. Cubic Li$_2$MoO$_4$ crystals show excellent performance of the dual heat-light read-out, efficient particle identification, and hints on high crystal radiopurity.