LPC meeting summary 25-01-2024 - final
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LPC meeting summary 25-01-2024 - final |
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Main purpose of the meeting: Chamonix rehearsal and Experiments Input
25th January 2024 Topic: Chamonix rehearsal and Experiments Input
Federico Alessio (Introduction)
- no comments
Andrea Ferrero (ALICE)
(Federico Alessio) The 2+2 days would give 0.6nb-1 more given our model of 0.15nb-1 per day.
Silvia Franchino (ATLAS)
(Chris Young) Do you need a low mu run at 13.6 fb-1 to monitor the radiation damage? No, it is thought that the high mu (usual) data can be used.
(Andrea Ferrero) Is it the calorimeter or ZDC that you need to monitor the radiation damage or year-to-year variations. The reply is that it is the jet response in the calorimeter that needs to be monitored.
Gianni Masetti (CMS)
(Silvia Franchino) Why do you need a VdM scan if you are just measuring the detector response? This will be asked to the HI experts.
(Silvia Franchino) Did you ask if 13.6 TeV data could be used to assess the detector conditions. This was asked and the HI experts said this was not possible.
(Silvia Franchino) Were the CMS HI community happy to lose the additional PbPb data. Yes, they were aware of this and were happy to lose it in exchange for the pp reference data.
(Federico Alessio) Can you provide the physics impact if we don't do the pp reference run in 2025. This will be followed up with the CMS HI team.
Elena Dall'Occo (LHCb)
(Federico Alessio) To clarify as you are wanting a lot of integrated luminosity do you only want to have one ppRef run in 2024. Yes, this is the position of LHCb.
AOB
(Andrea Ferrero) For the ppRef filling scheme in 2024 what will be the split in collisions. As the time limitation comes from ALICE it is likely that the filling scheme will be optimized for collisions in ALICE.
Federico Alessio (Chamonix Slides)
(Andrea Ferrero) Can you stress the yellow boxed data is not useful for physics, so the ALICE total useful data taken so far is even lower.
(Neils Tuning) Can you also mention the velo issue as well as the Phase-I commissioning.
(Silvia Franchino & aaa) If there are more bunches then mu=65 might not be possible for both ATLAS and CMS from the trigger point of view. It is more limited by lumi than mu so it is highly affected by the number of bunches. It is likely that ATLAS and CMS will start nearer to 60 than 65 when the machine is first full.
(Silvia Franchino) Did LHCf test the Arm2 detector in conjunction with ATLAS ZDC. They experts arrived at CERN recently and have contacted ATLAS ZDC. The tests will be on-going through the YETS. ATLAS RC will be included in the discussions.
(Mario Deile) The statement should be that TOTEM have completed their data-taking program. The Roman Pots are now part of CMS as the CMS PPS spectrometer.
(Riccardo Longo) The ATLAS ZDC is currently in the tunnel and the experts want to know what the LHCf plans are. Lorenzo gave the details of the proposed LHCf plans. ZDC use some of the LHCf cables so communication is key. LHCf will communicate their plans with ATLAS ZDC and discuss offline.
(Silvia Franchino) Does the lumi estimation include the change to have an additional MD day? No, as this is not yet confirmed.
(Andrea Ferrero) How much of this would be in MD and how much would be in physics data-taking time. This depends a bit on the details of the changes and if they affect normal data-taking.
(Andrea Ferrero) Why do we say that we are "comfortable" with 0.15nb-1. This will be re-worded such that it is clear that we want to be at 0.15nb-1 early in the 2024 running.
(Silvia Franchino) For BCMS would this still be with 36 bunch trains. Yes, this is the case.
(Silvia Franchino) There is also an INDIV request from ATLAS for once per week, it isn't only from LHCb.
(Michi Hostettler) If we go to 65 with the full machine we might reach the cryo limit and have to level anyway. In this situation INDIVs have less impact on the total integrated luminosity.
(Silvia Franchino) When will 2025 full-RP/keep half RP/other discussions happen? This is likely to be at the end of the summer.
(Andrea Ferrero) For VdM at point 2 the only requirement is the TCT but this doesn't need to be added to the slide.
(Lorenzo Bonechi) The motivtion for a high b* is that low b* results in a smearing of the angles resulting in poorer performance. If we go to values lower than 0.5m then we need to do new studies, and we would also need to discuss. With the squeeze outside the ramp there will be flexibility to change the b* but this would need to be agreed with ATLAS.
(Silvia Franchino & Gianni Masetti) Both experiments are discussing internally but it is likely to be the highest possible pile-up. But lower numbers of bunches is fine. Trains will require discussion with machine protection, for individual bunches this is easier. With 1.8 ppb and b* of 30cm we can get very high pile-up. The details of the request need to be discussed internally by the experiments.
(Silvia Franchino) The 20cm b* is not mentioned - why is this? It is unlikely to be ready so we were asked not to mention it, but it will be worked on for 2025 if it is not done in 2024.
AOB
(Chris Young) To CMS; you asked if it was possible to evaluate the detector conditions from the high mu 13.6 TeV, can you also enquire if low-mu 13.6 TeV could be used. This is easier to setup than a dedicated pp reference run. They will enquire about this with the HI team.