Picosecond timing resolution with 3D trench silicon sensors

In the high luminosity LHC phase, the collider will operate at a luminosity of 1.5 x 1034/cm/s and strict requirements will be posed on subdetectors capabilities. Concerning the LHCb Upgrade2 VELO, to guarantee a good detector performance, the additional information of the hit time stamping with an accuracy of at least 50 ps is needed. A very promising option today to achieve this level of timing precision is the 3D trench silicon pixel, developed by the INFN TimeSPOT collaboration. This kind of sensor would allow to build a 4D tracker, capable of excellent resolution in both space and time measurements. The latest beam test with the 3D trench sensors has been performed at the CERN SPS/H8 in 2021. By means of low-noise custom electronics boards featuring a two-stage transimpedance amplifier, it was possible to test silicon pixels and strips made with the 3D trench technology. To extrapolate the sensor time resolution, the crossing time of a particle was estimated using two MCP-PMTs as time tag, with an accuracy of approximately 7 ps. The beam-characterization was performed for both non-irradiated and irradiated (2.5 center dot 1016 1 MeV neq/cm2) devices. Preliminary results show that the standard deviation of the core of the pixels time distribution is about 10 ps and the tilted sensor has shown an efficiency close to 100%.