Minutes and Summary

Main purpose of the meeting: Meeting dedicated to review the current status of the ion run

Filip (Introduction)

Slide 4: MPP approved for going beyond 450b at the time of the meeting. 

 

Slide 5: Due to high losses, an intermediate step at 650b may be tried this afternoon. 

• Roderik commented at the meeting that it was recently discovered that some BLM thresholds were not properly applied for the energy at which they are supposed to work.

• Roderik also commented that another solution may be to reduce the octupoles strength, they were found to be quite high (unnecessarily)

• Roderik confirmed that opening the TCT L2 (towards ATLAS) seems to have improved the situation, but the opening would be so large that the triplet would be completely exposed (needs at least 30-3 sigmas).

 

Sarah (ALICE)

• Slide 2: 

  • Signature in time and direction with beam1, from ATLAS

  • The effect is there from the beginning of the fill, data taking is compromised throughout the fill

• Slide 9: Requested to have the same picture in a run where other IPs are not separated (only ALICE).

  • Roderik asked if the 100 factor margin scales linearly with the number of bunches. Sarah commented that the factor is to be taken with a grain of salt because it is all an estimation.

  • Roderik also asked if the Cside could become an issue. Sarah confirmed that it is unclear. 

• Roderik commented that there are a few ideas still to try. There will not be a single solution that can help. Filip commented that we should continue with the ramp-up and study the losses at ramp. 

  • More options will then be discussed when we will have a more global picture.

• It was requested to ALICE to investigate if there is a dependency on the filling pattern. 

• Andrea also suggested investigating the diagonal structure seen by opening the TCTs on B2. 

 

Gianni (CMS)

• Emittance scan in HI is useful for the LHC as well, however they are not needed for every fill. 

  • It was suggested to do it every other fill. 

  • ATLAS (Silvia) requests to have one at the beginning of each intensity step and around 2-3 times per week. Agreed that experiments call to ask for it.  

 

Silvia (ATLAS)

• Agree to run the last scan pairs at the end of a physics fill. 

• Niels asked if the other experiments need to be separated while performing the scan. Witold confirmed it would be nice, but not absolutely needed. 

 

Giovanni (LHCb)

• Michi asked what would be a factor in full collisions. Giovanni responded it is in the order of 10 more than this. 

 

Follow-up meeting in one week from now, October 9th.