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LPC meeting summary 11-07-2022 - final

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Minutes and Summary

Main purpose of the meeting: Planning for intensity ramp up and for the special run in September.

Minutes LPC meeting 11.07.2022
 
 
1) Introduction (Brian)
 
Topics today : expt. requests on ramp-up and planning for September special run.
 
Schedule for the next week is presented. If all goes well, 600b by Saturday.
 
900 GeV horizontal muons request from ATLAS dropped.
 
Phase know validation scheduled Wed afternoon.
Actual beam-beam MD to be scheduled next week.
 
72b fill: proposed to do offset leveling separately in IP1 and IP5 (to avoid blow-up of the beam)
 
Q to experiments: interest in quickly leveling to high lumi/intensity? TBD.
 
Q (Maciej): time in between first and second 600b fill? 
A: No, start on Sunday and then next one on Monday.
 
Emittance better than expected (1.6-1.9 um from dedicated scan). BSRT values too optimistic.
 
Updated plan for September special run on slide 18.
 
Q (Witold): can machine do beta* leveling while keeping the beam separated? (wrt calibration transfer run in 3rd box on slide 18)
A (Matteo): would require validation that takes longer than 45 minutes.
Proposal to do mu scan, then beta* leveling, then other mu scan. TBC.
 
Impact of crossing angle in ATLAS on LHCf commissioning:
Q to LHCf: can commissioning happen without crossing angle in ATLAS? Action item: find out.
 
Suggestion from Witold: possibility to do crossing angle variation during ALICE/LHCb VdM scan.
 
Slide 19: scan ranges to be discussed with MPP
 
2) ADJUST mode (J. Wenninger)
 
ADJUST mode is set automatically at end of tune change, before starting collisions. See details on slide 1.
Collisions in place before the optimization stage. Then all collimators are in final position (can be checked in DIP).
At this point, the expts could ramp up HV etc. 
Could consider to declare SB at this point. Or expts. could already start during ADJUST (check tertiary collimators around IP in DIP … when they are in reference position, all is safe).
But this is different for each optics. Alternatively, introduce a DIP variable that tells that this is done. OP will consider it. Action item on OP: introduce this flag in DIP.
 
 
3) Round Table
 
 
FASER (Jamie)
 
feedback from first Run3 data: 
trigger rate in 3b and 12b fills and extrapolated to 2E34. This gives 1.1 kHz rate, while originally 650 Hz was expected.
Not a problem per se.
 
Observed higher rate before AFP is inserted (30-40% reduction after XRP insertion). Seems to be due to TCL settings.
In particular, TCL6 setting is much tighter when AFP is inserted – this could be reducing the trigger rate by absorbing collision debris (TBC).
From FASER side: having AFP inserted sooner/more frequently is better.
 
Beam background: concrete shielding seems effective.
 
Comment from JW: TCL6 can be moved even if AFP is not inserted.
 
 
ALICE (Federico)
 
commissioning during 75b runs going well.
 
ATLAS (Joerg)
 
Most timing and HV scans done.
 
Emittance scan during each beta* step during last 75b fill was not useful due to operator mistake. Will request it again (during 300b?)
 
72b low mu fill tonight: if consecutive leveling in IP1 and IP5: ATLAS would like to go first. No objection from CMS.
Currently problem with MBST triggers. Hopefully will be solved by tonight.
Would like to have AFP inserted.
 
Happy for access on Wed (US15 and tunnel).  
 
 
CMS (Andrea)
 
Reminder: emittance scan requested in the beginning and end of every fill.
 
Low mu run with 600b: also CMS asks to level down to mu=1.
Will schedule this in 3rd 600b fill, to avoid separation leveling in both IP1/5.
 
 
LHCb (Federico)
 
LHCb requests extra 12b fill sometime in August. To be confirmed later, based on VELO progress.
 
SMOG injection available on “best effort” but generally only during working hours.
 
LHCb requests isolated bunches present in IP8 as long as possible.
 
Tests of the link between VELO to the BIS validated.
 
VELO closing procedure: to be discussed after commissioning is finished. No need for specific fill to test this. 
Confident in closing procedure. MPP should suggest strategy. Action item on LPC: discuss with MPP.
 
Massi file in preparation. Corrected version planned for next week.
 
Out of the 10 working hours shifts, LHCb requests ~50% of them in collisions in this phase.
 
 
Q (Brian): August 12b fill : after VELO is inserted?
A (Federico): yes. And full tracking system ready.
 
Comment from JW: VELO insertion validation is also about the heating.