Meeting on WP2 HSI related actions

6/R-018 (CERN)



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Guido Sterbini (CERN), Yannis Papaphilippou (CERN)
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Beam-beam and luminosity meeting
Nikos Karastathis
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G. Sterbini, G. Iadarola, K. Skoufaris, K. Paraschou, N. Triantafyllou, L. Blondel, L. Intelisano, N. Karastathis, S. Papadopoulous,  S. Kostoglou,  Y. Papaphilippou, H. Bartosik 

Guido  introduced the topic of the meeting: there are several actions open for the HSI section. They are opened by the LMC and the HL-LHC WP2. It is important to agree/discuss on the presented deadline for an optimal planning of the available resources (prioritization and work load-sharing).

Yannis presented the LMC actions: 

- produce an action list from the LumiDays for follow up at LMC (12.06.2019). Ilias circulated a draft this week. 

- keep looking at why B1 has a lower lifetime than B2, 27.09.2017. This is a long term collaborative actions. It requires to track B2.

- understand the source of additional losses at the beginning of the fill, 28.09.2016. These two items were already extensively discussed at Evian and in several beam-beam and luminosity meetings, with several progress done by Stefania, Gianni, Kostas, Sofia, Ilias, et al. I think it merits two presentations, one on the emittance evolution (and update of the luminosity model) and one on the lifetime. Both can be done on November/December 2019 (in particular to allow for lifetime simulations, including incoherent e-cloud). Gianni commented that the status of Kostas work can be presented as it was done at the impedance workshop. For a more in-depth presenation, additional time is required.

- check if the wire compensation is more efficient with flat optics, 02/03/2016. This seems to me an obsolete action, as it was demonstrated experimentally the efficiency of wire compensation in round optics, whereas in flat optics we do not have any experimental results but only very limited simulations for HL-LHC. An update on simulations can be given after the HL-LHC collaboration meeting (November 2019)

- study the origin of the 50 Hz lines that perturb the tune measurement at 6.5 TeV. Some more news (model of the load, 7 kHz origin?).  Sofia can give an update by December 2019, as there is a further extensive analysis of data which was already presented in the beam-beam meeting.

Guido presented the list of HL-LHC WP2 actions (also available here).
They are divided is 6 sets:
  1. SPS crab cavity tests
  2. Status of BB WS simulation tools
  3. BBLR compensation for HL-LHC 
  4. BB-WS and noise for flat optics
  5. Noise effects and emittance-BU in the HL-LHC
  6. BB weak strong actions 

There was a general consensus on the prioritization and work load-sharing. 

Yannis commented that when opening the actions is important to discuss in the WP2 the scope required for the studies and if there is missing input.

Gianni commented that several actions can be addressed in an efficient way only if we work on a correct software framework. Gianni pointed out that there is a great potential in that respect in python. Guido commented that python could serve as a glue for the standard tools (MAD-X and Sixtrack). Yannis agreed on the method.

Guido proposed to use the BB meeting to track the advancements of the work related to the actions and to report the status of the action as AOB to the WP2 meeting, in order to inform about the action's status and the time/resources needed to pass to the next steps. 

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