Minutes and Summary
Main purpose of the meeting:
Schedule for rest of 2022, ramp-up planning, planning for vdM scans, possible switch to mixed scheme, beam spot length in IP1/5.
1) Introduction (Brian)
Topics: schedule for rest of 2022, ramp-up planning, planning for vdM scans, possible switch to mixed scheme, beam spot length in IP1/5.
No ion run in 2022. Extended ion run in 2023. Formal decision on Wednesday at the LMC.
Outline of reduced Run 3 plan on slide 4.
Short term schedule on slide 7:
- vdM/LHCf setup and ATLAS non-linearity scan completed.
- LHCf physics run wrapping up. Removal of detector on Wednesday, during SPS MD.
- Ramp-up to start on Thursday. LHCb NOT ready to insert VELO.
LHCf record fill: 57 hours of stable beam!
Post-TS1 planning, see slide 10.
Ramp up for MPP to be rediscussed since VELO will not be included.
Post-TS2 planning, see slide 11.
Need to see with MD responsible if any high lumi in MD2.
Plan for LHCb VELO insertion on slide 12:
- partial insertion (to 5 mm): will need dedicated 12b (< 1 hour) and 300b fill (~ 1 hour).
- once ready for full insertion: plan ramp up with 12b (30min), 300b (2hours), 1200b (2hours).
- then ready for insertion in normal fills
Filling schemes post-TS1 on slide 13:
- Options for 8b4e and mixed schemes presented by Lotta in LMC.
- propose to start with 36b trains (also ramp-up)
- then consider to switch to mixed scheme?
Mixed filling schemes now ready in injectors (slide 14):
1 batch of seven 8b4e + up to four 48b batches
Possible filling scheme has been prepared.
No need for ramp-up with mixed scheme (unlike for pure 8b4e).
Considering LHC test with ions: slide 15
very low intensity, 1 or 2 fills. Similar to what was done with Xe in 2017.
Would need SB, useful to benchmark ALICE O2 computing performance and disk needs
+ test of crystal collimation with ions.
E.g. on Thu/Fri of week 46 (TBC).
Roderik: no technical showstopper. Rough estimate 1.5 days.
Possibly also test injection of slip-stacked trains.
Longitudinal beam spot size (slide 16-17):
- IP1 beam spot shorter than expected
- also systematically 6% smaller than in IP5
- beams in ATLAS round within few %
- initial bunch length a bit shorter than expected and dropping faster during fill than expected (to be understood)
Witold: abs lumi numbers from both ATLAS and CMS have a ~5% uncertainty, so be careful with drawing conclusions from the ratio at this point.
Stephane: longit. bunch distribution might have tails (cleaned quickly by bb), which give you wrong numbers at the start.
Next meeting on October 3rd.
2) Round Table
ATLAS (Joerg)
Very successful collaboration between LHCf collaboration and ATLAS, in particular the ZDC group.
Recorded 1,784,687,835 events, T0 transfer close to 8GB/s over the entire weekend.
ZDC detector removal on Wednesday morning
Thank you to LHC for BBA of AFP and ALFA (successful AFP data taking during LHCf run, ALFA timing-in data yet to be analysed) and Non-Linearity scans on Friday morning
(very successful, data already analysed).
12b fill removed (TBC).
ATLAS toroid ramp-up (need 5h to ramp magnet and take calibration run, after 1200b fill)
MD2 schedule will be fixed by Wednesday.
Should not be problem to run with mixed filling scheme, provided PU reasonably low. Still need to decide on optimal PU settings.
CMS (Gaelle)
VdM scans for CMS during LHCf fill (7178)
VdM scan program completed successfully with ~32 hr of scans!
Comprehensive scan program is invaluable and will inform future vdM programs.
Also GEM latency scan.
BPTX status: Timing measurements interrupted due to oscilloscope failure today at ~4h. Recovered with manual intervention at ~6h.
Oscilloscope HD will need replacement (target: Wed).
May request mu scan during 150b (end of the fill while ATLAS is head-on).
BRIL colleagues brought cake ;-)
LHCf (Lorenzo)
very successful data taking!!
More than 3 x 10^8 triggers (Arm1 + Arm2) (2 positions).
Ready for uninstalling on Wed. morning. Will take full day (till ~17h). In contact with transport team and RP.
ALICE (Sarah)
Very happy with long LHCf fill.
ZDC commissioned. External crossing angle +145 urad, BRAN retracted.
IP shift as discussed in July/August. In last fill of August moved back to nominal value. What happened?
Brian asked for exact fill number.
JW: maybe crossing plane optimization did not work.
Will resume intensity scans as soon as possible.
