ARC-BPAC December 2025 (rehearsal)

Monday 15 Dec 2025, 06:00 → 08:00 Europe/Berlin

https://speakapp.link/to/OoZbkw

ARC-BPAC indico:

https://kds.kek.jp/event/57962/ (Pw: 202512)

06:00 → 06:20 Accelerator operation issues and how they have been addressed

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

Speaker: Kyo Shibata

SuperKEKB_challenges&countermeasures_16.pdf

06:20 → 06:35 Belle II operation issues and how they have been addressed

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

Speaker: Katsuro Nakamura (KEK)

251218-BelleIIShutdownWork_JointReview.pdf

06:35 → 06:55 Accelerator operation status

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

Speaker: Makoto Tobiyama

06:55 → 07:15 Accelerator operation plan

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

Speaker: Gaku Mitsuka

07:15 → 07:35 Mitigation plan for beam backgrounds and SBLs

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

Speaker: Hiroyuki Nakayama (Belle (SuperKEKB Experiment))

20251218_ARC-BPAC_v3.pdf

20251218_ARC-BPAC_v5.pdf

07:35 → 07:55 Belle II operation status & plan

• 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

Speaker: Kenta Uno (KEK)

2025.12.14_Kuno_BPAC.pdf

2025.12.14_Kuno_BPAC_v2.pdf