Heidelberg 2022 – scientific programme

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T: Fachverband Teilchenphysik

T 68: Detector Systems 2

T 68.6: Talk

Wednesday, March 23, 2022, 17:30–17:45, T-H27

Commissioning and Results of a Scintillator Based Beam Abort and Machine Protection System at SuperKEKB — •Ivan Popov, Hendrik Windel, and Frank Simon for the Belle II collaboration — Max-Planck-Institut für Physik, München, Deutschland

The asymmetric-energy collider SuperKEKB started its physics operation in March 2019. The usage of the nano-beam scheme enables collisions of electrons and positrons at record-breaking luminosities, but requires continuous particle injections at a rate of 50 Hz. These injections result in periods of high backgrounds, which can negatively affect the operation of Belle II subdetectors. In order to monitor and mitigate such backgrounds, the CLAWS detector system, consisting of scintillator tiles read out by silicon photomultipliers, has been in operation in various forms since 2016. Beginning with the first physics run in 2019, 32 sensors have been distributed along the final focusing magnets. Over the course of SuperKEKB's run time in 2020 they have proven to reliably observe disturbances in the particle beam which can result in catastrophically high backgrounds and quenches of the final focusing magnets. An electronics upgrade together with the implementation of a smart trigger logic enables the generation of a beam abort trigger within 200 ns after the occurrence of excessive background, thus ensuring the safe operation of the experiment. The CLAWS have been operating as a beam abort system since May 2021. In this report, the commissioning of the system and results achieved are discussed, and an outlook on plans for its further expansion is given.