Construction and qualification of the Barrel Timing Layer detector at the CMS experiment

The high luminosity era of the LHC (HL-LHC) aims to answer several important questions of elementary particle physics, such as, for example, the Higgs boson self-coupling and the existence of physics beyond the standard model. However, it brings new experimental challenges such as greater particle multiplicity, increased number and density of proton-proton interaction vertices (pileup), and high radiation dosage. Consequently, novel techniques are necessary to maintain good reconstruction performance and exploit the full potential of the experiment. The Barrel Timing Layer (BTL) is one of the new state-of-the-art detectors that will be installed in CMS, dedicated to measuring particle arrival time with a tremendous precision of 30-60 ps. Precision timing measurement will serve as an essential tool in tackling the challenges of HL-LHC and is expected to have a significant impact in improving its physics potential. This talk will describe the design and construction of the BTL and, particularly, the qualification/quality-assurance procedure of the sensor modules (that use LYSO crystals, read out by SiPMs) which is quintessential for achieving the target performance.