Minutes of 110^th Impedance Working Group meeting

Date: 27/1/2026

Present: Chiara Antuono, Sergio Calatroni, Elena de la Fuente García, Miguel Díaz Zúmel, Patrick Krkotic, Elena Macchia, Nicolas Mounet, Hermann Pommerenke, Julian Sonpar,Pavlina Trubacova, Christine Völlinger, Daniel Wollman, Carlo Zannini.   

AOB: pre-Chamonix discussion

1. D. Wollman has to present about ''LHC beam limitation protection strategy for the 2026 high intensity test'' by touching the following:

• Light review with previous experience with non conformities (TCLD, 6L2)
• Limitations expected in 2026 (TCLD, TCDS, RF fingers, cryo/e-cloud limits)
• How to push intensity in MDs high intensity test? (steps to reach the HL bunch intensity with BCMS, advanced intensity pushing to MD1 reaching 40% more heat than in the normal operation to probe unknown limitation)

• Are all known non-conformity going to be addressed during LS3? (also the unknown to be identified and repaired during LS3)

• How to create new non-conformities in the high intensity test?

• Conclusions:
  • MPP supports the high intensity to beam tests and has prepared procedures to operate beyond the currently known operational envelope.

Daniel asked about a possible plan for Run 4  concerning the TCLD, if the smaller gap mitigation is enough and safe to run with it. Carlo answered yes, that was tested both from beam impedance and collimator team confirmed it can be accommodated without issue.

2. Carlo Zannini has to present about "Beam performance of injectors and view for 2026" and concerning the beam impedance, the main topics are:

• MKPS heating
• Limitations summary, particular attention is required for the 8b4e filling scheme, due to its specific filling pattern. Tests still need to be finalized, as additional issues related to sparking may arise
• PS Booster transverse instability from the extraction  kicker cable which is still limiting the high intensity operation
• The rest of the talk is related to beam performance and reliability run.

Miguel asks why he mentioned the 8b4e and Carlo says that there are several requests, and there is a possibility for the 8b4e, even if it is with less priority , therefore injectors have to be ready to give all of them.