Minutes and Summary

Main purpose of the meeting: Preparation for 2024 data taking

LPC minutes 25th March

Introduction (Chris Young)

(Chris Young) It was suggested that we could produce filling schemes where there are INDIVs only for some experiments which could allow another 48b batch. However, all experiments said that they are interested in occational INDIVs throughout the year.

(Catrin Bernius) It was asked which experts are needed for the beam tailoring MDs and this is the luminosity experts who confirmed that they would be there.

(Chris Young) It was clarified that the decision on the shift of the EYETS will hopefully come this week before people leave for Easter.

(Catrin Bernius) Will there be a specific LPC where the VdM configurations will be dicussed. Yes, we will have one but it doesn't need to be the next meeting. We will send a message when we want to have a meeting on this topic, with some notice so people can prepare.

(Lucia Silvestris, Jorg Wenninger) It was asked when the Roman Pot alignment will occur as this will occur before the next meeting. It will be in the week after Easter but it isn't known which day. People will have to be flexible. The morning meetings will continue to give updates on the schedule between the LPC meetings.

ALICE (Andrea Ferrero)

(Chris Young) You mention that you want 8 colliding bunches, would you still be happy with less than 8? For less then we would need more than 10h at injection to get a meaningful dataset.

LHCb (Elena Dall'Occo)

No comments

CMS (Giulia Negro)

(Jorg Wenninger) It would be good to see this at Flat Top, but once we declare stable beams then if we change things then we need to re-validate.

(Roderik Bruce) Is there any way to see this before stable beams are declared. No, this isn't possible.

(Jorg Wenninger) To clarify, is positive outwards or inwards. It is inwards so the beam needs to be moved outwards.

(Federico Alessio, Jorg Wenninger) Could we do a 3 bunch, non-leveled loss map, to validate just this configuration, do the measurement and bump, then do all the loss maps. The other consideration is that the aperature would need to be measured before declaring stable beams.

(Chris Young) Are you not worried about the y-position. No, this is stable which is what we care about rather than the absolute value.

(Chris Young) This takes very little data to measure so small numbers of bunches and low charge is fine.

(Jorg Wenninger) Without the aperature measurement we wouldn't have the collimator setting for stable beams either.

(Stephane Fartoukh, Giulia Negro) It was pointed out that moving the beam outwards increases the radiation damage on the triplet. Between 2022 and 2023 CMS requested a move outwards of 1 mm and it was agreed to only move by 0.5 mm based on this radiation argument. The request is not to move back to the position of 2023, not to move it further outwards than this.

(Chris Young) It was confirmed that for the afterglow studies, while stable beams is not required the beams do need to be colliding.

ATLAS (Catrin Bernius)

(Chris Young) For the emmitance scan ATLAS and CMS should do their emmitance scans in the same fill. We should coordinate this so both experiments are aware when these are going to occur.

AoB

(Andrea Ferrero, Federico Alessio) Do you need MASSI files for the collisions at injection energy? It would be nice to have them if you can produce them but if you don't have them this is not a problem.

(Jorg Wenninger, Experiment contacts) It might be the case that over the Easter weekend that there might be a focus on the daytime without much activity in the LHC at night. This would mean that there wouldn't be beam in the machine at night. The experiments all welcome collisions at injection during the daytime and would appreciate some notice of when this will occur.

(Chris Young, Jorg Wenninger) For the FASER test will this still be done over the weekend. Yes, as long as the TCL6 is aligned before the weekend this will be done. Several data points could be done in the case that there is not much activity. This would also give useful collisions to all experiments.

(Jorg Wenninger) In the week of the 8th April, on the Tuesday or Wednesday (potentially after the first stable beams) there will be the cryo re-configuration and there will be access possibilities in parallel.