Minutes and Summary

Main purpose of the meeting: To discuss 2026 schedule - proposal for heating test in MD1 and risks

LPC minutes 19 January 2026

Present (P = in person): Chris Young (P), Chiara Zampolli (P), Martijn Mulders (P), Eric Torrence (P), Archie Sharma (P), Robert Muenzer (P), Juan Esteban (P), Flavio Pisani (P), Stefano Redaelli (P), Giulia Negro, Anna Sfyrla, Dragoslav Lazic, Federica Oliva, Georges Trad, Johanna Wanczyk, Mika Huhtinen, Riccardo Longo, Richard Hawkings, Tomasz Bold

Introduction (Chiara Zampolli)

Paula Collins: LHCb is happy with 5 fb as target, along the lines of the comment from last week.

Filip Moortgat: CMS is happy with 30 fb as target for the pp run.

 

Flavio Pisani (LHCb): to have the vdM scan before MD1 might actually be preferred.

 

Jorg Wenninger: this scenario B [all high-mu running in one block before MD1] has a small advantage. Fewer changes. 

 

Maciej Trzebinski: the extended bba estimate is for full alignment. For the pp reference run we fit everything in one fill (half a shift) … this is really an over estimate for the BBA. Chiara Zampolli: anyway I don’t think we can accommodate and bba. The priority during these two days is LHCb.

 

Jorgen Wenniger clarifies that the mention of the ‘horizontal muons’ on Mon 23.02 in the preliminary schedule is a random placeholder (as a reminder).

 

Silvia Pisano: you mentioned Heavy-Ion running could be extended; do you mean at the end, during the time now scheduled for the High Intensity tests? Chiara Zampolli: yes, just to make sure that experiments are aware and if this possibility becomes true, that we are not limited by experiments not having shifters or the magnet switched off. So that we care not earlier, but maybe extended during HI days at the end
Silvia Pisano: is the ramp-up schedule final? Chiara Zampolli: yes it is the same as in 2025. I did not confirm with Christophe. I will check with him. Jorg Wenninger: no reason to change. 

 

Silvia Pisano: for feedback on vdM : what exactly do you need? Chris Young: I think in Run2 they figured out a way of beam tailoring that improved the non-factorisation significantly… it was then forgotten in 2022-2023. But was used again in 2024-2025, so there should be significant differences.  Chiaria Zampolli: it would be good to show in Chamonix, as it involved quite a bit of work from the injector teams. 

High-Intensity test proposals and planning for MDs (Sofia Kostoglou)

Chiara Zampolli: we are Ok with doing the single beam tests, but not with two beams. 

Sofia Kostoglou: it is possible that we will not have time to do tests with both beams in those two days. But we can learn something from them that we cannot learn with single beams. But this does not have to be decided now.

Chris Young: if you break something with two beams it is likely in a high-radiation area, which we would like to avoid. You can do all of the tests planned for the first six days of the HI test with single beams. 

Filip Moortgat: this is all based on the assumption that the experiments are more open to risk in MD1 than MD2. I think if you ask the experiments you might get a very different answer. 

A lively discussion follows speculating about the possible answers from different experiments, risks of different parts that could break during the high-intensity tests. 

Jorg Wenniger points out that it is all about risk management for Run 4, and that we are interested to find a ‘bigger problem’ than a single non-conformity of a part that can be replaced in a YETS. 

Flavio Pisani points out that LHCb, the 2026 run is really important, and that Run 4 will not bring a gain for LHCb. Actually, at HL-LHC the prospects are slightly worse, due to shorter fills. 

Paula Collins confirms that for LHCb the priority is to go into the long LS3 shutdown with the largest pp dataset possible, and minimal risk. It is hard to understand what this additional test will really bring. 

Sofia Kostoglou: it all depends on the priorities. Are the 2500 fb-1 that ATLAS and CMS will collect in Run4 the priority? Or the data we expect to collect in 2026?

Jorg Wenniger: you gain by advancing ONLY if there is a problem just behind the corner. If there is no problem MD1 will be smooth and everyone will be happy. To profit from what you learn you somehow must commit yourself to then do something. If something breaks and we don’t act on it, it would be strange. 

Roderik Bruce: of course the risk is that you run into several problems. You could find one problem in the beginning. If you only find this in the HI test, we will not find anything else behind. We could look a bit stupid if we run into a problem in HL-LHC and we have not done what we could do to test it before. 

Sofia Kostoglou: identifying a problem does not automatically mean that there should be an intervention. For example last year we had this TCLD problem that caused a vacuum spike. But nothing was broken. We had time to come up with a mitigation through studies, simulations or other means. And this is what this will give us. 

Paula: what fraction of possible problems would be investigated with this test? If it would only a small fraction it would change the benefit vs risk calculation.
Sofia Kostoglou: this we cannot know.
Roderik Bruce: I don’t think we know exactly all the possible things that could go wrong. It is impossible to say what fraction. The only thing we know is that you have a chance to come back twice. 

Jorg Wenninger: the whole point is that we would like to avoid that in Run4 you have to a year or more to fix something big. 
Chris Young: yes the point is to find a whole family of something that needs to be re-designed or fixed. Jorg Wenniger: you gain 4 years to think already about the problem and prepare for an action.

Filip Moortgat: it is reassuring that you propose to go in small steps of 100 bunches so you might see something already without breaking it. 

Roderik Bruce: one reason to do it in MD1 and not in MD2 is that we get more time to think about a mitigation before the high-intensity test. 
Chiara Zampolli concludes by asking the experiments for feedback on what they think about these plans, what they would be willing to risk. We should probably avoid the two beams. We also discussed that if we lose time because we have to do an intervention, the time should be shared between physics and MD. So this is our proposal as LPC.
Martijn Mulders: do we want to keep the idea of doing it in MD2 on the table?
Chiara Zampolli: lets ask the experiments and see what they would prefer. And also the machine should tell us what they would prefer. Please discuss with your management and let us know by Wednesday evening, as we are meeting with the Director of Research on Thursday.   

CMS (Filip Moortgat)
Some splashes would be very much appreciated! (not sure how many).

CMS will have some low-mu requests during ramp-up. 

ATLAS (Eric Torrence)
Discussion about the AFP bump, with the conclusion that if included it could probably stay for all runs except the vdMeer scans.
Chris Young: the low E run should deliver a few pb^-1 of data, not nb^-1. 
Filip Moortgat: would CMS automatically get collisions if ATLAS asks for it? Because it is symmetric? Jorgen Wenninger: not necessarily. 

ALICE (Silvia Pisano)
Jorg Wenninger confirms that on February 4 they can make sure that somebody is in the CCC who can ramp up/down the ALICE magnet
Silvia Pisano: are optics and filling scheme the same for low-PU as for the standard pp? Jorg Wenninger: yes.
Silvia Pisano: will luminosity readings be needed during HI test? Filip Moortgat: CMS is planning to switch off the magnet, so we can give you something that is proportional to the luminosity but not the absolute scale. Sofica Kostogloul: this worked well in the past, so would be ok. 

LHCb (Flavio Pisano)
No slides 
Yets activities proceeding as usual
No replacement in VELO of damaged modules (impact on physics did not justify it: we lose a bit of acceptance in the very forwards region ) … too risky to take detector apart and replace broken modules.
I don’t think we will need a magnet off run this year, no special requests at the moment for the intensity ramp-up. 
For the low-E run: preparing with the minimum baseline astroparticle cosmic-ray study. If there is more time we are ready to fill it in with more measurements. 
We will check if >24h fill length could cause a problem or not.