Quality Assurance Tests of the LHCb VELO Modules

The LHCb experiment has a dedicated vertex detector (VELO) to measure the particle’s tracks close to the interaction point. This paper describes the main steps of the quality assurance tests performed during assembly, reception and installation of the LHCb VELO modules. Visual inspection, electrical tests, thermal tests and metrology measurements were made. A burn-in test of the modules was performed in a vacuum environment similar to that of the LHCb experiment. The signal to noise of the sensors was estimated to be 20.4 3.0 for R sensors and 22.4 3 0 for Φ sensors. The modules were tested up to 350 V and the leakage current of the modules did not exceed 20µA at any stage of the testing. Only 0.6% of channels were found to be noisy or not fully functional. The acceptable operating pressures of the modules in vacuum was also evaluated.