Minutes and Summary

Main purpose of the meeting: Discuss 2026 schedule, targets, and configuration. Finalise proposal for the advancement of two days of the high intensity test.

LPC minutes 26 January 2026

Present (P = in person): Chiara Zampolli (P), Martijn Mulders(P), Chris Young (P), Eric Torrence, Filip Moortgat (P), Krystian Roslon (P), Andrej Gorisek (P), Flavio Pisani (P), Xavier Buffat (P), Matteo Solfaroli (P), Alexi ( P), Archie Sharma (P), Joanna Wanczyk (P), Juan Esteban (P), Georges Trad (P), Roderik Bruce, Silvia Pisano, Stephane Willocq, Witold Kozanecki, Federica Oliva, Andres Delannoy, Anna Sfyria, David Stickland, Klaus Monig, Maciej Trzebinski, Matthew Nguyen, Paula Collins, Riccardo Longo, Richard Hawkings, Mirko Pojer, Tomasz Bold

LPC intro (Chiara Zampolli)

Slide 11 (Matteo): 50/15 is still being discussed. We need to decide before commissioning. Xavier agrees: I would not leave it as an option. We either fold it in or we don’t.

Slide 17 Paula clarifies that for LHCb MD2 is preferred over MD1. As little risk for pp as possible if it is done. 2026 is a crucial part of Run 3, after the Upgrade 1 in 2024. 

Slide 18 causes a lively discussion about how much risk is acceptable. Matteo and Xavier and George argue that the option in MD1 to test only with single beam up to 25% heating beyond operational envelope (as shown in slide 18) would not be sufficient to make the test worthwhile from the machine perspective. The goal is to anticipate a little bit of risk from the end of the year and move it earlier, to leave time to react in case any problem is found. Filip and Paula acknowledge emphasize again the importance of ensuring useful physics data taking in a short year, for which hundreds of people will be involved in running the detectors, while also acknowledging the usefulness of the high intensity tests. It is not so obvious how to balance these conflicting priorities and it is suggested that the final decision should be taken at higher management level. 

Slide 19 is followed by a discussion about the ordering of the low-PU and high-PU data taking. Both ATLAS (Andrej) and CMS (Filip) initially expressed a preference to have high-PU first. If MD1 contains risk, CMS prefers to do low-PU first, while ATLAS still has a slight preference to do high-PU first (but only if CMS does the same). Chiara clarifies that one argument to do low-PU first is that there is still a small uncertainty about whether it works to do both experiments at the same time (even after the studies look promising, and a short test during commissioning that is planned). If it does not work, this schedule would still allow enough time to do one experiment (CMS) first, and the other experiment (ATLAS) second. Filip and Andrej agree this would be a possible solution. 

On slide 20, Filip clarifies that he is still checking whether CMS needs 10 splashes. Matteo clarifies that if not needed it would be better not to do it, since there are small risks associated to the collimator movements (due to stress on the bellows). This consideration could be more important than the small amount of time it takes to do the splashes.

Regarding the desired energy for the “1 TeV” run, Paula Collins clarifies that 1.2 TeV is acceptable but 1.0 TeV is preferred. 
The question is raised what configurations other experiments want. Maciej (for AFP) mentions that they studied the optics for beta * varying between 11 and 3.1 m, and the lower beta * the better for the acceptance. This is based on an insertion to 20-25 sigma, assuming this is possible without the need for beam based alignment. 

Silvia: not sure we will be able to give feedback on vdM non-factorisation, as analysis of the Run3 data is still ongoing. We will let you know. And a question: when do you want to have feedback on collisions for 1 TeV? Chiara: in the next 2 weeks would be good. 

About the plans for switching experiment magnets off at end of year, Matteo clarifies that It might be best (for e-cloud) to keep magnets at nominal, but for CMS it has been discussed to switch off the solenoid and we have to take it. For other experiments, if it does not matter much it is best to keep them on. 

George wonders if switching off the magnet means no lumi will be provided, and LHCb might not close the VELO.  This is to be planned carefully, since part of the heating test is to estimate the impedance of the VELO. Paula agrees this needs to be planned carefully. 

Filip ensures that lumi of acceptable quality can be provided w/o magnet, as was done in the past. Andrej: ATLAS even wants to take data so will likely keep the magnets on. 

Paula mentions that once the 1 TeV run configuration is known, it needs to be discussed with the VELO group. 

ALICE (Krystian Roslon)

Matteo and George: ok with ALICE test on Wednesday February 4. Juan has the morning shift in CCC. 

CMS (Archie Sharma)

Filip clarifies that as splashes are not for free they will make sure they are really needed.

ATLAS (Andrej  Gorisek)

A question on behalf of AFP: is it possible to have 15-30 mins of stable beams at end of the BBA fill? Matteo: this is highly non-standard. It is theoretically possible, also because the intensity is low. But personally I would discourage this strongly unless really important. Andej: we will discuss with AFP to see if it is really that important. 

LHCb (Paula)

No slides

Lot of work going on in cavern; among other things we double-checked the belt tension in the VELO which had an issue last Summer, and also the performance of the BCM which potentially could cause an interruption to the beam. Also the cooling which was very problematic in 2025. In the short YETS we are doing what we can to improve stability. The SMOG detectors in the cavern which caused data loss last year were replaced. Please update the table for the feedback from LHCb on the high intensity test. Thanks for all the work on the low-E run . We are very excited for this.