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LPC meeting summary 13-06-2022 - final

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Minutes and Summary

Main purpose of the meeting: Experimental requests for beam commissioning and ramp-up periods

 

1) Introduction (Brian)

 

- slide 3: overall 2022 schedule unchanged. Firstly 13.6 SB confirmed for July 5th (~16:30).

There has been a request from the scrubbing team to switch off all solenoids for a scrubbing (~3 day) run. This is because a solenoidal field suppresses the e-cloud in the area where the field is present (so the beam pipe around the experiment would not be conditioned). ATLAS and CMS are very hesitant to ramp down their solenoid for this reason. Scrubbing of the experimental areas could be postponed till a more convenient time (when solenoids are off for other reasons). To be discussed further with the Technical Coordination teams.

- slide 4: list of completed requests.

- slide 5: remaining experimental requests.

Trains for next SB fill still TBC. Roman pot alignment TBD.

- slide 9: experiments should requests invid. bunches in the ramp-up filling schemes if needed.

Note the comment on the bottom of the slide that the non-colliding 12b in the beginning of the filling scheme cannot be maintained with a full machine (some will need to collide). 

- slide 10: first proposal for VdM/LHCf plan in September. Feedback welcome.

Q(Witold): crossing angle needed in IP1 for LHCf run. For LUCID, needs to check the effect of the crossing angle. Request to do a validation scan for this (technically, similar to crossing angle levelling).

- slide 11: reminder to the experiments to provide Massi files to exercise the propagation.

 

Q&A

Q (Gianni): when will we know if 8b4e is needed?  

A (Giovanni Iadarola): there is margin in 2022, so will not need it in 2022 unless serious cryo problems; expect to know at the end of 2022 if we might need it for 2023. 

 

Q(AFP): if want to insert RPs for the LHCf run, when is the last moment that we should inform the machine?

A(Jorg): Latest mid-end of August, but the sooner the better.

 

2) Plans for beam-beam tests (Joanna)

 

- slide 4: knob validation still to be scheduled (3 x 40 min)

- updated plan for Test 1 on slide 5

- updated plan for Test 2 on slide 6

- parasitic measurements performed during non-linearity test on 04.06.2022, see slide 8

- BSRT beam width measurement very good, see slide 9

 

Q (Brian): shaping the beam during injection possible?

A (Witold): Delphine did some shaping, but shape was not so much an issue, rather emittance.

Q (Witold): Why does emittance drop at 450 GeV, while there is no synch. radiation?

A (Joanna): may be (partially) effect of the fit.

A (Enrico): may be effect of tails. BSRT not yet fully commissioned & calibrated (need at least 10 nominals).

C (Davit Stickland): should do a wire scan before, middle and after.

 

Q (Brian): operational steps a bit missing (bunch intensities etc). Would be good to have this.

 

C (Stephane): slide 4: why so big phase shift? Should be symmetric positive/negative.

A (Joanna): result of simulations

A (Witold): to maximize beta beat

To be followed up offline.

 

C (Jorg): maybe use next SB fill to check the beam parameters with BSRT scan.

 

 
3) Round table of experiments
 
 
LHCb (Federico)
 
- slide 4: accelerator mode sequence important
- slide 10: today, SciFi took data for first time with C-side.
                 SMOG injection test done today. Successful.
                 In case of “calm” beam periods, would like to inject during recommissioning (provided it doesn’t disturb the LHC commissioning)
 
 
Q (Jorg): to test all interlocks (VELO etc.), when will this happen? 
A (Federico): next week or 2 weeks from now. VELO expert will contact LHC.
 
 
 
ATLAS (Joerg)
 
- ATLAS in good shape, NSW still being commissioned. 
- horizontal muon fill went well, see slide 3.
- slide 4: request for another horizontal muon run of about 2-3 hours (nightshift is ok).
- slide 4: no HV on RPCs till early July (RPC cleaning with Argon, need frequent short accesses)
- slide 4: emittance scan in ATLAS now with 15 points instead of 9 (improved shaping)
 
C (Roderik): horizontal muons: if you want higher intensity, need about 20 bunches, so longer injection needed.
C (Witold): non-linearity scans showed very good reproducibility wrt. the one from Oct 2021.
 
 
CMS (Gaelle)
 
- non-linearity scan was successful
- slide 3: yesterday LHC tried nominal collimator settings and background indeed reduced a lot (see slide 4)
- slide 5: CMS will switch OFF trackers for scrubbing run. Back ON for Jul 5. Having SB a bit before Jul5 would be helpful.
- slide 6: to be done: Massi file machinery debugging
 
 
Q (Jorg):  will switch off HV again if scrubbing after July 5th?
A (Gaelle): yes, no problem. 
 
 
ALICE (Federico)
 
 
- slide 4: ramp up schedule
              note effective crossing angle on bottom. TBC. Final numbers will come.