Pawel Jalocha (University of Oxford (GB))
The LHCb Vertex Detector (VELO) will be upgraded in 2019 to a lightweight, pixel detector capable of 40 MHz readout and operation in very close proximity to the LHC beams. The thermal management of the vacuum-resident system will be provided by bi-phase CO2 circulating in micro channels embedded within thin silicon substrates onto which active elements are placed. This solution has been selected due to the excellent thermal efficiency, the absence of thermal expansion mismatch with silicon ASICs, the radiation hardness of CO2, and very low contribution to the material budget. The R&D effort for LHCb is focusing on the design and layout of the channels together with a fluidic connector and its attachment which must withstand pressures in excess of 200 bars. Even distribution of the coolant is ensured by means of the use of restrictions implemented before the entrance to a race-track layout of the main cooling channels. In this talk,a characterisation of a realistic microchannel prototype will be presented and compared to simulation. The design of a suitable fluidic connector, together with the vacuum soldering technique will be described.