Minutes and Summary

Main purpose of the meeting: This meeting is mostly dedicated to the near-term schedule and the ramp-up fills. 

Introduction (Filip)

Many successful activities in the past 2 weeks. For a summary, see slide 3 and 4.

• Wednesday 19th there will be a 24h access, for cryo reconfiguration ad SPS wire scanner fix

• Strong wish to have all of the SPS wire scanners working

  • If approved, then recovery will take all day Thursday until ~10pm

  • Even with the shift in schedule, it is possible the first 3b+12b Stable Beams fills may happen over daytime on the week-end. Even 75b can happen as early as Sunday.

 

Regarding the outstanding list from the experiments:

• Horizontal muons planned for tomorrow, starting 8am

• Agreed that the ATLAS fill at very low mu (0.005) with 64 isolated bunches would happen during the ALICE/LHCb VdM fill

• ALICE 0/0 magnet scan step will be done at 75b fill (one of the two fills)

• LHCb VELO tomography will happen during the 400b fill

• Nobody is interested in another 450 GeV Stable Beams fill

 

Ramp-up fills:

• New requirements from MPP is to have at least 2 fills and >15h in SB per step

• New step wrt to last year: remove 300b and 600b steps and merge them into a 400b step. 

  • By default intermediated steps (red in slide 7) are not in the plan. However, filling schemes are maintained in case it would be decided to do them.

  • Currently, up until the filling scheme with ~1800b there will be 3 INDIVs, with 2 INDIV collisions for all experiments. Afterwards, a discussion needs to happen to decide how much and which experiments need them. 

• Jorg commented that currently the SPS cannot deliver 200ns spacing. 

  • It may affect the 400b step. To be seen when we approach the step.

 

New 2023 schedule has been updated (v1.1.1): MD2 block has been moved to August 15-20 (was July 22-26). 

• Under discussion the FASER/SND emulsion exchanges

• One extra day of TS1 has been added (for the crystal collimation fix) and the 90m(120m) b* run will happen on Sunday 25 June at the moment

• In terms of near-term schedule, the 400b fill is currently scheduled after the scrubbing fills. LHCb would prefer this.

  • Jorg commented that it will depend on the progress in the next days

  • ALICE 75b fill will be dedicated to the magnet 0/0 fill considered quite important for ALICE. They need at least one fill. 

  • Scrubbing start date is uncertain, but currently planned for early next week. Could be two or three days depending on beam conditions, injectors availability etc. 

 

Some latest news from the LHC Beam Operations Committee (LBOC)

• Proposal to move to 25ns beams instead of BCMS beams for 2023 operations

  • This is transparent for the experiments

• High and very high beta optics:

  • 90m there is a first version, but not final yet. 120m hopefully coming soon. 

  • The optics for the very high beta* runs are in preparation considering the requirements TOTEM/ALFA. 

  • Hasko from ALFA said that in fact they also prefer 3/6km after more investigations. Ilias will be contacted.

• In the ion cycle, it was decided to go to b* = 0.5m, operationally this is easier as it is already commissioned and it provides a marginal ~2% gain in luminosity.

• There is quite a sizable discrepancy between longitudinal luminous region measurements in ATLAS/CMS .

  • ATLAS commented it is possible their measurement may not have been reliable due to lack of cooling and magnet. 

 

CMS (Andrea Massironi)

• Observed a +1cm Z luminous region position shift. Asked if it is possible to shift back to 0cm

  • Jorg and Filip commented that once we see that all data from all experiments agrees, it will be adjusted at 6.8 TeV. This can be done live during a fill. 

• CMS asked to participate in the low mu runs in // with ATLAS. Answers to questions on slide 4 were provided during the meeting:

  • ATLAS confirmed they would prefer to do the low mu fill after TS1. Either the 400b step or the successive step (likely ~1200b).

  • CMS cannot be separated at the same time as ATLAS, but can be done afterwards. This can be coordinated.

  • The hours taken for the scans are in principle not part of the MPP validation, but we agreed that the fill can be kept longer so the extra time “comes for free” 

  • It is also confirmed that the very low mu fill for ATLAS would be done during the ALICE/LHCb VdM scan and CMS cannot be separated, so CMS can run at the nominal PU.

 

ALICE (Sarah Portebouef)

• ALICE will profit from the access on Wednesday to fix a MCH damaged fiber

• Important to schedule the 0/0 magnet fill run

  • 75b fill can happen as early as Sunday

• ALICE requests collisions in IP2 during the ATLAS/CMS VDM scan

  • This is ok

 

ATLAS (Silvia Franchino)

• Still problems with the solenoid, root cause not understood. Currently it will be powered on Thursday 20th in time for the start-up. 

  • Problem may reoccur and ramp-up requests will come back in the list.

• Investigations on the beam mode changes explained in slide 4 will be done in OP

• Still follow-up needed for the beam background measurement at ALFA, requested to be done after the 90m b* run.

 

LHCb (Niels Tuning)

• Preference that 400b fill (where VELO tomography would happen) is done after scrubbing, due to a problem with VELO cooling 

  • After tomography, there would be need of an access to check the VELO foil status

  • Validation of VELO movement can only happen the Technical Stop as it needs multiple tries of movements in and out

• Emittance scan at end of fill (head-on) is easy to be done. Emittance scan on the separation plane is trickier. Jorg suggests to start with the emittance scan when head-on. Could be tried during the 75b fill, in between the beta* leveling of ATLAS/CMS

 

SND (Ettore Zaffaroni)

• To discuss the dates for the emulsion exchanges

 

Given the fast evolving schedule, the next LPC meeting is scheduled for next Monday 24th April at 2pm.