The time-of-propagation counter for Belle II

TL;DR

The paper discusses the design and optimization of the time-of-propagation (TOP) counter for Belle II, a particle identification device crucial for high-precision flavor physics measurements at the upgraded KEKB accelerator.

Contribution

It introduces the optimized configuration of the Belle II TOP counter, demonstrating its capability to distinguish kaons and pions with high confidence up to 4 GeV/c.

Findings

Achieves 4 sigma kaon-pion separation up to 4 GeV/c

Utilizes micro-channel plate photomultiplier tubes for precise timing

Optimized design enhances particle identification performance

Abstract

The Belle II detector operating at the future upgrade to the KEKB accelerator will perform high-statistics precision investigations into the flavor sector of the Standard Model. As charged hadron identification is a vital element of the experiment's success, the time-of-propagation (TOP) counter has been chosen as the primary particle identification device in the barrel region of Belle II. The TOP counter is a compact variant of the detection of internally reflected Cherenkov light (DIRC) technique and relies heavily on exquisite single photon timing resolution with micro-channel plate photomultiplier tubes. We discuss the general principles of TOP operation and optimization of the Belle II TOP configuration, which is expected to provide 4 sigma or better separation of kaons and pions up to momenta of approximately 4 GeV/c.