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.