Investigation of CO₂-based cooling for the CBM Silicon Tracking System

As the core detector of the CBM experiment, the Silicon Tracking System (STS) located in the dipole magnet provides track reconstruction and momentum determination of charged particles from beam-target interactions. Due to the expected irradiation damage, the sensors will dissipate some power and have to be kept at or below -5 ^circle C by complete removal of the heat dissipated by the front-end electronics (FEE) boards (∝40 kW). The heat must be removed to avoid thermal runaway and reverse annealing of the irradiated silicon sensors. So the STS will be operated in a thermal insulation box and will use bi-phase CO₂ cooling system for the FEE. Thermal conductivity measurements between different thermal interfaces will be shown by using higher thermal conductivity interface materials to replace all the space that otherwise would be occupied by air. Water will be used as the coolant for measurements, which will then be verified by using bi-phase CO₂. This effort is towards building a cooling demonstrator for two STS half-stations to show that the CBM-STS cooling concept is viable. Thermal interface results, both experimental and simulation, followed by the initial construction R and D of thermal insulation box and their respective future plans are presented.