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Belle II Restarts: First electron-positron collisions observed after 18 months maintenance
On February 20, 2024, the Belle II experiment resumed data acquisition for physics measurements.
Belle II is a particle physics experiment designed to investigate the properties of particles, such as B mesons, produced by the SuperKEKB accelerator. This research aims to study new physical phenomena that are crucial for understanding the mechanisms behind the creation of the universe.
Operations were suspended for about 18 months starting in the summer of 2022, and major improvements were made to both the accelerator and detectors. Beam operation of the accelerator resumed on January 29 this year, and the first electron-positron collision was observed at 22:12 on February 20. We will continue to accumulate data for physics measurements while confirming the effects of the improvements made during the long-term maintenance period.
Contribution of N Laboratory, Nagoya University
N-Lab has developed and operates the TOP Counter, a particle identifier for the Belle II detector. During the long-term maintenance period that began in the summer of 2022, the photodetector used in the TOP Counter was replaced with an upgraded model.
Regarding the upgraded photodetector, Prof. Kenji Inami stated,
“The improved photodetector is capable of detecting photons more efficiently and with greater tolerance to light loading. We expect to be able to undertake data taking with higher precision in upcoming physics runs!”
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