Minutes and Summary

Main purpose of the meeting: pp data-taking, preparing for PbPb, and 2026 plans

LPC minutes 27th October

Introduction (Chris Young)

(Paula Collins) Given that 1.5 days of pp physics was moved from last year to this year to allow the MD to move technically the targets should be adjusted. Therefore we probably haven't quite got to the targets yet.
(Chris Young) Yes, but we should also account for the one heavy ion day that was moved to this year for NeNe so the adjustment is only 1/2 a day. We can calculate what the adjustment should be.

(Roderik Bruce) Depending on availability the background test timing could shift a bit in either direction.

(Roderik Bruce) There are a few points with low intensity eg. cycle setup earlier as well as the loss maps.

(Roderik Bruce) The negative polarity setup is a placeholder so this can move, and 
(Chris Young) Could we move this setup to ensure that the checklist doesn't fall in the night.
(Roderik Bruce) This setup also requires experts to be present.
(Chris Young) The idea would be to move it or not move it such that we do fills through the night and checklists during the day.

(Robert Munzer) Note that the week after is LHCC week so it would be good to get the VdM program done earlier rather than later.
(Roderik Bruce) Is there still a preference for daytime at the weekend?
(Robert Munzer) Daytime is better but there isn't a strict requirement other than unavailabilty of the experts on Tuesday.

(Roderik Bruce) Do we have an timing for the SND bump test and optics knob test?
(Chris Young) Yes, we hope that it will happen on Thursday afternoon after an access where FASER have to remove an emulsion as the 
(Paula Collins) You announced the dump at 8am. Is there some flexibility around this on the day in case a fill has recently started? Experience has shown that it is very difficult to time the fills to be finishing at 8am. 
(Chris Young) If it is only a couple of hours then there is very little gain. We can look into it, and if there can be more flexibility, but many other teams usually plan to utilize the slot in parallel.
(Paula Collins) If people are using the shadow of the access then they should be required to be flexible.
(Chris Young) We will investigate the possibilities.

ALICE (Robert Munzer)

(Michi Hostettler) The drop is when we 1.4e11 in beam 1
(Chris Young) We did have some fills with both beams at 1.4e11.
(Michi Hostettler) It looks much more consistent now, but comparing to the best points before it is quite similar, but previously there was quite some variation.
(Robert Munzer) Lower beam 1 intensity does seem to be beneficial for the ALICE background. I will look at some normalization of the background by beam current.
(Georges Trad) Has it flattened since we stopped increasing the intensity at 1.8e11?
(Robert Munzer) Yes, it appears to now be stable.

(Chris Young) These targets look quite achievable/reasonable.
(Roderik Bruce) Have the final leveling values been decided?
(Robert Munzer) We will try some different values but decide during the running. It is thought to be most likely in the 30-35 kHz range.

CMS (Archie Sharma)

(Chris Young) For the lower mu 2x5h you can just phone the CCC before (so they can warn cryo) and they will say if they want to do it or if they want you to just adjust the target.

ATLAS (Andrej Gorisek)

(Andrej Gorisek) Clarified that the 12h VdM statement refers to pp and not PbPb/pPb.

(Georges Trad) Note that ion setup is before the TS.
(Chris Young) We will try to find the time that the last beams will be dumped asap.
(Georges Trad) RP will determine the dump time.
(Andrej Gorisek) The toroid will be ramped down before access begins in the ATLAS cavern. This is why we want to know the time of the last beam.
(Michi Hostettler) Are you so pushed for time during the TS or could you shift things later?
(Andrej Gorisek) We could run things an hour later but would prefer not to.

(Andrej Gorisek) Please make sure that the luminosity requests are accurate as they are missing for some MDs where we expect them.
(Chris Young) 17403 there will be collision in trains with stable beams 17383 we expect collisions but not in stable beams. 

(David Stickland) Is the 12h the combined ATLAS+CMS time or just ATLAS, and does this include length scale and calibration transfer parts? 
(Andrej Gorisek) This will be checked, but it is in the ATLAS request, and we are thinking of dropping the 2 calibration transfer fills.

(Chris Young) Thank you for the clear statement on the DOROS MD proposal.

LHCb (Paula Collins)

(Michi Hostettler) Nothing has changed on the LHC side for the z-position but maybe it is a side-effect of the polarity change.
(Chris Young) For the z, we did change the beam length blow-up.
(Michi Hostettler) Yes, but this should change the length rather than the position.

(Chris Young) Is the BCM condition still being used?
(Paula Collins) Yes, if we suspect the velo is in danger it will still be extracted.

(Chris Young) For the 1 TeV run I did some quick simulations of the integrated luminosity expected if we ran in a similar way to the oxygen run with 60 bunches and staying within 4x the setup beam limit. This doesn't get anywhere near the numbers you quote. Therefore we can't accomplish this program with a series of pilots, but need to use nominal bunches. Usually at the start of the year we need several fills with 15h in collision for each step and several steps are needed to get to 200 nominal bunches, before doing the physics. We will need to discuss exactly what is required with Machine Protection. 
(Michi Hostettler) You need to think about how to do this in terms of time dedicated to intensity ramp-up and time dedicated to physics. In MD we have done some shorter ramp-ups and this configuration won't be used again afterwards, but MP still needs to be on board ensuring the machine is safe. Additionally the cycle is not very long as there won't be beta* steps etc. so perhaps several intensity ramp-up fills can be done quickly - cycle+turn-around could be 2h. But the ambitious targets look impossible within 48 hours. If we do a long ramp-up it is maybe worth spending more time to take a bigger dataset, but this would need to be balanced against the rest of the physics program.
(Chris Young) Does the SMOG data use all the bunches, both those colliding in LHCb and those not-colliding? 
(Paula Collins) Yes, but I will double-check.
(Roderik Bruce) Does the 48h include the commissioning?
(Chris Young) Yes. It is to be seen how much of the time this will take, but this is why I was trying the same strategy that was used for Oxygen. This will need further discussion.

(Andrej Gorisek) There is a proposal so save some time during the VdM optics fill, by eg. dropping one of the length scale scans, but the main gain is dropping the calibration transfer fills.