Minutes and Summary

Main purpose of the meeting: Plan for 2026; special run configurations; timing of the Technical Stop

LPC 9 February 2026

Present (P = in person): Martijn Mulders(P), Eric Torrence (P), Filip Moortgat (P), Krystian Roslon (P), Flavio Pisani (P), Paula Collins (P), Matteo Solfaroli (P), Jorg Wenninger (P), Archie Sharma (P), Joanna Wanczyk (P), Juan Esteban (P), Julia Negro (P), Michi Hostettler (P), Sofia Kostoglou (P), Matthew Nguyen, Jeroen Hegeman, Andrej Gorisek, Witold Kozanecki, Tomasz Bold, Klaus Monig, Maciej Trzebinski, Gerardo Vasquez, Richard Hawkings, Brian Petersen, Stephane Willocq, Riccardo Longo, Dragoslav Lazic, Anna Sfyrla, Ivan Amos Cali, Reyes Alemany Fernandez, Daniele Mirarchi

LPC intro (Martijn Mulders, Chiara Zampoli)

Slide 6: Paula and Flavio clarify that LHCb would like to do a magnet flip around the middle of the “low-mu” period, and also around the middle of the “high-mu” period, with the goal to equalize the amount of data with magnet Up and magnet Down. 

Splashes: the danger is that collimators would traditionally make extreme movements, with the risk of causing a vacuum leak, especially in edge-welded bellows that are known to be a weak point. If instead we can provide splashes without moving the collimators, by moving the beam with a bump instead, it would avoid this risk. Jorg clarifies that Splashes may be scheduled a bit later in the program, so not before the first collisions. Filip clarifies that this is not a problem, but the earlier the better (since the splashes are used for detector calibration). 

Proposal to move the TS: Roderik clarifies that it is not possible to have 3 days of heavy-ion commissioning before the TS and only 1 day after. That means in the current proposal the TS would have to move to Whit Monday. In principle there are no objections from the experiments, as long as efficient Transport (with two parallel teams) can be guaranteed, which could be problematic on a public holiday. 

Filip asks whether it would be possible in the case of significant downtime to move a few days of high-PU pp running at the end of the Heavy-Ion run, as by that time we don’t have concerns about the ZDCs. Before the heavy-ion run, the max luminosity tolerated by ZDC without affecting performance is about 1 fb^-1. We would have to check with RP if this is Ok. They put limits on high-intensity running during the last 2 weeks of the Run (for the high-intensity test). But this would be just before the final 2 weeks. Jorg comments that switching back to pp after heavy-ion would not be very efficient.  

SND (Gerardo Vasquez)

SND needs a 4h access to fix an issue with their DAQ boards. Jorg comments that given that this sector comes late it is probably best to do it early.. Better now than next week. Georges Trad is doing the coordination.

CMS (Archie Sharma)

Some discussion about moving the TS. Matteo points out that moving TS to a public holiday has never worked in the past. And we don’t have a strong motivation at this point.

ATLAS (Andrej  Gorisek)

Discussion about local vs global coupling corrections for the vdM scans. Richard clarified that it is the local correction they are interested in. But it would take about 3h of extra commissioning time. So far this is not included in the schedule. To be followed-up offline. [[ A message from Richard on February 10 points at the presentation by Tatiana Pieloni and Joanna Wanczyk at the LLCMWG on https://indico.cern.ch/event/1637578/ and after some discussion it is concluded that since the studies are preliminary we currently don’t have a strong case to justify spending the extra commissioning time on measuring and correcting the local couplings ]]

Maciej clarifies that the request to have 1h of data taking at mu ~0.5 with separated beams, at the end of the nominal BBA is more about measuring backgrounds than checking alignment. 

ALICE (Silvia Pisano)

If it is transparent, ALICE may ask to also have collisions for the 1.2 GeV run. It will be 400b and 11m beta *. Silvia estimates that they would target a rate of about 100 kHz. To be confirmed.

The request from ALICE to do a z-position scan of the vertex by +- 5 cm during the 75 bunch fill, with ALICE magnet off, will need to be synchronized with the other experiments (who would also be affected).  A more detailed plan will be presented next week. Filip: the other experiments need to know, in case they are planning something special during that fill, since their collision point will also move. 

LHCb (Paula Collins)

Discussion about crossing angle settings.. Jorg believes that a mistake was made for the ppref in Oct 2024, and indeed some problems were seen. Michi clarifies that for the other runs (PbPb in 2024 and pO in 2025), while internal and external angles were opposite, the net angle was negative, like the external angle, which is fine. 

Paula stresses that with the same sign, the crossing angle pushes the limit of the acceptance. Sofia points out that the external angle can be reduced a bit, but it will not make a big difference since the angle is dominated by the internal angle.