Accelerator operation issues and how they have been addressed

• Kyo Shibata

Issues ** Beam size increase due to beam-beam ** Small dynamic aperture (short Touschek lifetime) ** Low injection efficiency (2nd bunch control, orbit jitter, emittance increase at BT, beam-beam, emittance increase at a larger charge at Linac) ** Poor stability and reproducibility ** Lack of monitors ** SBL Summary of the work during the last shutdown to address those issues

Belle II operation issues and how they have been addressed

• Katsuro Nakamura (KEK)

Issues: ** Beam background (detector performance, detector life, DAQ stability) ** Detector damage by SBL ** Lack of on-site experts Summary of the work during the last shutdown to address those issues

Accelerator operation status

• Makoto Tobiyama

Confirmed improvement by the work during the last shutdown Plan and result of 2025c run Issues in 2025c and how they have been addressed ** Hardware troubles and recovery procedures ** Physics run time less than 50% ** Lower injection efficiency than 2024c ** Lower specific luminosity than 2024c

Accelerator operation plan

• Gaku Mitsuka

How to achieve 1/ab and 1 x 10^35 /cm^2/s ** How to reach LER > 2.0 A and HER > 1.4 A, issues to be addressed to reach it, and how to address it. ** How to keep 80% of physics run time and how to improve the accelerator operation efficiency Machine studies Plan ahead for possible issues and contingencies

Mitigation plan for beam backgrounds and SBLs

• Hiroyuki Nakayama (Belle (SuperKEKB Experiment))

- Collimator - Faster beam abort - PXD HV fast shutdown - Belle II HV emergency shutdown interlock for machine failure

Belle II operation status & plan

• Kenta Uno (KEK)

- Current status of the beam background, SBL, and DAQ - How the countermeasures for the issues are functioning in the operation or what improvements were confirmed during this run - Operation arrangements and expert staffing - Further improvements or implementation of remaining countermeasures - Detector studies - Strategy or criteria to turn on PXD