Search

The LHCb VELO Upgrade I, currently being installed for the 2022 start of LHC Run 3, uses silicon microchannel coolers with internally circulating bi-phase \cotwo for thermal control of hybrid pixel modules operating in vacuum. This is the largest scale application of this technology to date. Production of the microchannel coolers was completed in July 2019 and the assembly into cooling structures was completed in September 2021. This paper describes the R\&D path supporting the microchannel production and assembly and the motivation for the design choices. The microchannel coolers have excellent thermal peformance, low and uniform mass, no thermal expansion mismatch with the ASICs and are radiation hard. The fluidic and thermal performance is presented., 31 pages, 27 figures

LHCb is the dedicated b-physics experiment of the LHC. Its vertex detector, the VErtex LOcator (VELO), will operate in a harsh radiation environment with limited access due to its proximity to the LHC beam. To ensure the long term operation and performance, every module was required to pass a set of quality assurance tests. These were specifically developed for the VELO modules to take into account their operational environment and assembly steps. Each VELO module was rigorously inspected, tested and thermally cycled in the Glasgow module burn-in procedures. This paper provides details of the burn-in procedures and summarises the main results that were found. Some of the major results presented in this paper are: the full characterisation of the leakage currents; identification of bad channels; and signal to noise measurements. A few minor problems were identified through visual inspections of the modules and the feedback into the production process proved critical. As a result of the electrical and thermal tests, one module out of the 45 that were tested was rejected due to its thermal performance. Studies are also reported, based on individual modules, characterising the front end read out chip pulse shape.