The operation and performance of the TOP detector at the Belle II experiment

Kazuki Kojima

31 October 2021

Abstract: The SuperKEKB/Belle II experiment, the successor of the KEKB/Belle experiment at KEK, started the physics data taking with the full detector system in March 2019. The Time-of-Propagation (TOP) detector was integrated into the Belle II detector for charged particle identification in the barrel region. The TOP detector mainly consists of quartz radiators, Micro-Channel-Plate (MCP) PMTs, and front-end electronics. It reconstructs a ring image of Cherenkov photons generated by an incident particle. It measures the timing of each detected photon with an accuracy of less than $100~\mathrm{ps}$ for good $K/\pi$ separation. In the operation of the TOP detector, harsh beam-induced background in the high luminosity environment is one of the critical issues to keep the particle identification performance. We developed various tools to monitor MCP-PMT performance and to identify and fix errors arising from front-end electronics during data taking. The TOP detector provides $85\%$ $K$ identification efficiency at a $10\%$ $\pi$ misidentification rate in the data at the early stage of the experiment. In these proceedings, we present the operation status and the performance by the summer of 2021.

Keyword(s): TOP ; MCP-PMT ; EPS-HEP ; EPS-HEP2021 ; PID ; 2021
Note: 15 minutes (12 minutes presentation + 3 minutes Q&A)

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 Record created 2021-10-31, last modified 2021-10-31

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