Calibration and commissioning of the Time Of Propagation PID detector at the Belle II Experiment

Abstract The Time Of Propagation (TOP) counter is a novel particle identification detector which relies on the precise detection time of Cherenkov photons produced by charged particles traversing a quartz bar. The TOP counter is constituted by 16 modules that cover the barrel region of the Belle II detector. Each module is instrumented with 32 Micro-Channel-Plate Photo-Multiplier-Tube (MCP-PMT) detectors, which are read out by dedicated fast waveform-sampling front-end electronics. After recalling the performance goals and stringent design requirements of the TOP counter, a comprehensive overview of its calibration strategies will be given. The status of the integration with the other Belle II sub-detectors and the performance during the commissioning phase with cosmic ray data will be presented, along with a preliminary study of the first SuperKEKB collision events.