LPC meeting summary 07-11-2022 - final
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LPC meeting summary 07-11-2022 - final |
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Main purpose of the meeting: Scheduling of last 3 weeks of 2022 run, recent LHC performance VdM plans, ion test plans.
1) Introduction (Brian)
Topics of the day: scheduling for last 3 weeks of 2022 Run, recent LHC performance, plans for vdM scans, ion test period.
Remaining schedule 2022 on slide 3.
SND emulsion replacement done last Friday.
Floating MD on 22/23 Nov.
LHC performance:
~6.4/fb delivered October 27-November 2 to IP1/5. New record lumi in a day 1.18/fb on November 2.
New record for bunch intensity (1.46x10^11 ppb at SB) in fill 8334. Had to offset-level a bit to stay at PU=54. Last beta* step reached after 6 hours.
Backed-off intensity in following fills since hitting cryo limit in the ARCs.
MKI heating also potential issue with long back-to-back fills.
Options for last 2 weeks: keep current configuration or switch to hybrid configuration?
Plan for VdM scans on slide 7:
- 3 setup/validation fills (no SB)
- IP2/8 scan: on request of David, the order is suggested to be ATLAS/CMS/LHCb/ALICE.
- 600b ramp-up inserted on request of MPP. ATLAS separated. No emittance scans.
If this would be used for the LHCb dipole OFF data-taking, then we would extend this fill to 2h.
Ion test: see slides from Roderik
Input requested for LHC performance workshop at CERN in December.
Next meeting on November 14th.
2) Update on 2022 Pb ion test (Roderik)
Schedule starts at noon on Nov 17th.
ALICE requested different crossing angles for both fills. TBD with MPP.
First stable beam fill:
https://lpc.web.cern.ch/schemeEditor.html?user=lpc&scheme=2022/Special/Single_20b_8_16_8_1bpi_20inj_PbPbtest2022.json
Second fill:
https://lpc.web.cern.ch/schemeEditor.html?user=lpc&scheme=2022/Special/50ns_20b_8_20_5_8bpi_6inj_PbPbtrains.json
Injectors doing very well: achieved 2.2E8 Pb/bunch with slip-stacked trains.
Might not fit all single bunches to respect the setup beam limit. Might have to ask the slightly lower intensity from injectors.
Updated performance estimate on slide 4.
Simulated luminosity after 5h on slide 5. Might make first fill shorter and second fill longer, see slide 6.
Everybody was happy with this proposal.
3) Round Table
ALICE (Sarah)
In past week, 3 HI rate pp tests up to 4 MHz.
Still 2 HI rate pp tests to be scheduled in the last 2 weeks.
Requests for VdM programme:
ALICE Magnet and crossing angle during VdM
• L3/Dip +/+ -> the internal half crossing angle sign is negative
• The effective half crossing angle at IP2 = -72(internal) + 145(external) = +73 microrad
Collimator openings relevant for ZDC operations
• TDI (+-55 mm) and TCDD (+-20mm) are open as expected
• up to now the TCLIA is opened at 56 mm ( +-28mm) as in run2 (giving a crossing angle limit +-66 microrad)
• for run3 the TCLIA should instead opened at 59 mm (+-29,5 mm ) which sets the crossing angle limit +-100 microrad
BRAN should be retracted
Leveling request in ALICE during scans on slide 4-5 (low mu running).
ALICE programme detailed on slide 6-7.
Pb test: ALICE configuration on slide 9:
Magnet polarity during Pb test
• L3/Dip +/+ -> the internal half crossing angle sign is negative
Target Crossing angles
• Fill with single bc
• The effective half crossing angle at IP2 = -72(internal) + 172(external) = +100 microrad
• Fill with trains
• The effective half crossing angle at IP2 = -72(internal) + 128(external)= +56 microrad
• have the smallest angle to compensate for the high b* but of course if the value is too close to the operational limit 60 would do as well
Collimator openings relevant for ZDC operations
• TDI (+-55 mm) and TCDD (+-20mm) are open as expected
• up to now the TCLIA is opened at 56 mm ( +-28mm) as in run2 (giving a crossing angle limit +-66 microrad)
• for run3 the TCLIA should instead opened at 59 mm (+-29.5 mm ) which sets the crossing angle limit +-100 microrad
BRAN should be retracted.
ALICE datataking goals for 2023:
- pp data taking
• production for physics at 500 kHz interaction rate. Target Lumi 8.7 Hz/ microbarn
• with regular high rate scans from 5 kHz to 4 MHz interaction rate for Pb-Pb commissioning
• 3.5 MHz interaction rate has an equivalent track load to Pb-Pb 50 kHz
- pp reference run
• production for physics at 1 MHz interaction rate
- Pb-Pb data taking
• Energy decided with results of Pb test for crystal collimation
• Data taking at 50 kHz interaction rate levelled with ZDC
LHCb (Federico)
Plans for remaining weeks of 2022 on slide 2
VdM scans
LHCb magnet OFF fill(s)
Mu(pileup) scan up to mu = 7
Test emittance scan procedure in LHCb during SB fills
Ion data taking, requires multiple collisions in LHCb
Plan for VdM on slide 3.
Chosen to run with VELO *not* fully closed.
Request to start with ATLAS LSC, not LHCb VdM.
• We need some time to validate trigger and recipes.
• Could not do it last week due to injection activity during daytime
1. +/- 3.5 sigma XY VdM scan (SMOG-less)
2. 2D spiral + diagonal VdM (SMOG-less)
• Steps 1 and 2 should take ~67 minutes without interruptions.
• Count at least 30 more minutes for instabilities.
3. Inject SMOG. Wait stabilization, about 15 minutes.
• Still to decide if to inject in SMOG cell (SMOG2) or vessel (SMOG1)
4. +/- 4.5 sigma XY VdM scan
5. 2D spiral + diagonal VdM
6. LSC +/-4.5 sigma
7. +/- 4.5 sigma XY VdM scan with finer steps around the center
• Steps 3 to 7 should take ~127 minutes without interruption. Add extra time…
CMS (Andrea)
Lumi instabilities in fill 8335, 8345. Disappears after optimization. Any understanding?
JW: must be due to moving beam. Source unknown. Could be many reasons, but points to something moving locally in IP5.
In either filling scheme scenario: max PU be kept at 55 in CMS.
ALTAS (Joerg)
Preference to stay with 36b BCMS till end of the year. Motivations on slide 2.
Plan to start 2023 ramp-up with hybrid scheme.
End-of-fill emittance scans, if needed by LHC for beam evolution studies, could be added back, shortened to 9 scan points if permitting.
Michi: prefer not to mix scans with 15 points and 9 points. Machine operators will decide.