Minutes and Summary

Main purpose of the meeting: Meeting again dedicated to short-term news and post-TS1 schedule. 

 

Filip (Introduction)

• Slide 3.

  • Currently intensity per bunch is limited to <1.6 x10^11 (decision post-LMC).

  • commissioning of high beta* optics for the 120m run is being done in between the physics production period. Even if not sure, the VdM scans for ATLAS/CMS can actually start a little earlier if the commissioning is successful before the MD+TS period (starting on Wednesday 15th June).

• Slide 9. 

  • David commented that the luminosity difference between ATLAS and CMS seems to be time dependent rather than luminosity dependent. This seems to point to machine related issues. Jorg commented that indeed it is expected that emittance blow-up is more common in H, but this seems to be going in the opposite direction as shown in the plot. More to be understood. 

  • Catrin asked whether the leveling is done on the luminosity or the pileup? Michi answered this is done on pileup, but the pileup is inferred from the luminosity that it is being distributed via DIP. 

• Slide 15. 

  • Mario commented that likely PPS will request to align an horizontal pot alignment. Hope that the validation can be integrated in the initial 3b fill. 

• Slide 17.

  • Low mu (0.5-1) scan (3.5h) expected to be done in the 400b step for ATLAS.

  • Jorg commented that the BBA background measurement for the very high beta*  run cannot happen much earlier than the run itself. Silvia responded that if the background measurement is bad, the run will be affected.

 

AoB. Jorg asked how much scheduling flexibility do we have after TS1? Not everything needs to be done sequentially, but can be done in parallel as well. Filip commented that what we are interested in is the total amount not the scheduling. Witold commented that some “time off” between two VdM steps could be beneficial for the experts. 

 

Gianni Masetti (CMS)

• For the low-mu fill, to be defined how many bunches would be desired. It can be done in the ramp-up fills, to be decided in which fill and to be coordinated with the ATLAS low mu fills.

 

David Stickland (CMS VdM)

• Witold asked what a “super-separation scan” is. David answered it is a +/-5 sigma scan. 

 

Witold Kozanecki (ATLAS VdM)

• Slide 5. Schedule is agreed at the meeting by CMS expert (David).

• Slide 6. Question regarding beam brightness. Filip commented that there should be a beam that is satisfactory, but there is no proof of it. Same comment applies to the non-factorization question. There is no MD planned, but work has been ongoing on the topic. 

• Slide 7. 

  • Jorg commented it is ok to switch Orbit Feedback OFF during the ATLA VdM scan. 

  • Jorg commented that tune measurement is very poor this year so likely the 3 digits request will not be possible. Even before going into collisions.

    • Witold asked to know what reasonable uncertainty would be available. It is one of the biggest beam-beam systematics.

• Slide 9. 

  • Bunch intensity will be as high as available from the LHC, 1.5x10^11 ppb seems reasonable. 

 

Silvia Franchino (ATLAS)

• Slide 2. 

  • Test at a very high pileup (>65) needs experts in the CCC as it enters the danger zone. Above 2.1-2.2x10^34 in luminosity we need to be careful. 

    • Will be tried to be done before MD but needs scheduling. It will be followed-up. 

• Slide 3. 

  • Plans for better conditioning of 4.L1 are currently not clear.

  • Proposed to make a checkpoint with vacuum experts and obtain feedback from ATLAS.

• Slide 4.

  • Filip commented that Stephane Fartouk promised to provide optics by the end of this week. Unfortunately, this will not give feedbacks for LHCC. 

 

Niels Tuning (LHCb)

• Request to do a mini-VDM scan in LHCb during the ATLAS/VDM scan.

  • It will be coordinated in the long fill, in between a transition step between ATLAS and CMS scans

• INDIV is important for LHCb. But working on find a way to compensate by “categorizing” bunches of different types (to provide a similar plot as with an INDIV).

 

Sarah Porteboeuf (ALICE)

• Michi asked to call the CCC when increasing the target lumi. 

 

Next meeting tentatively scheduled for next Monday 12 June and possibly Friday 23 June at 2pm (To Be Confirmed).