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LIU Beam Parameter WG meeting #2
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Europe/Zurich
874/R-018 - salle de réunion activité CCC (CERN)
Notes:
General
- In the SPS performance we should add a line concerning 'beam loss and optics choice', separated from the limitation coming from protection devices and heating. Losses with LHC beams are already now a problem in the SPS in the present optics configuration, if they increase this would either impact the loss budget of the SPS (and increase the requirements on the upstream machines) or become a new limitation, because losses above a certain value are intolerable, unless a collimation system is implemented in the SPS
- The different items listed in the summarising table need to be followed up:
- PSB brightness line: E. Benedetto will wrap up the studies at the PSB injection WG meeting on 12 January - Action: Malika to report from the LIU-PSB injection WG meeting and propose baseline assumption at next meeting (12 February).
- Longitudinal emittance @PSB extraction: Summarise 2015 studies and outline perspectives to achieve the wanted values of longitudinal emittance out of the PSB. Potential contributors: A. Findlay and S. Hancock. Some questions: are we limited with the C16 voltage right now? Can we do MDs in Ring4 using the Finemet as C16 (or on a different harmonic number) to increase or optimise the blow up? Do we need any improvement in the LLRF ? - Action: Bettina to organise the follow up and propose next steps.
- Bunch length @PS injection: Summarise known information from recombination kicker rise time measurements + 2015 measurements and outline studies in 2016. Potential contributors: W. Bartmann and G. Sterbini. Some questions: What is the current experience with transferring longer bunches than 180 ns with LHC beams? Is there any measurable emittance growth due to kicker? - Action: Giovanni to contact Wolfgang and Guido and ask them to present in one of next meetings.
- PS performance: Can we define the intensity reach of the PS after LIU considering longitudinal coupled bunch instabilities, electron cloud, TMCI at transition? - Action: Heiko to present where we are standing and outline of needed studies in one of next meetings.
- SPS performance I: Longitudinal instabilities. Action: Elena to keep the WG up to date with the results from ongoing simulation studies on SPS intensity reach after impedance reduction.
- SPS performance II: Protection devices, dumps and kicker heating: Actions: Verena to summarise what are the present intensity/brightness limitations and current work. Brennan to check with Mike Barnes the status of MKP/MKE heating studies with LIU beam parameters and possibly improved designs and report back.
- SPS performance III: Beam losses. We need a summary of the present concerns (e.g. from the scrubbing run experience with high intensity, operational experience with LHC beams) and needed actions to take care of the problem - Action: Verena and Hannes
- Ion beam paramater table: Produce achieved beam parameters, make educated guesses on future performances, generate and propose the LIU parameter table - Action: Hannes and Giovanni (update at next meeting on 12 February)
Ions, 2015 performance along the injector chain from the current status of data analysis
- From the present figures, the strongest losses occur losses at SPS flat bottom: for the intensities injected in 2015 into the SPS, the rms value of the extracted bunch current plateaus as a function of the injected value. Possible candidates to cause the effect are space charge, IBS and rf noise, or whatever interplay between them. Can we disentangle among the different effects? How do losses scale with the injected intensity? What is the dependence on flat bottom length? What are the perspectives for improvement after LS2 (e.g. with the new LLRF and therefore RF noise reduction)?
- Michaela's tool to calculate integrated luminosity is necessary also to optimise production scheme in the injectors (e.g., check impact of different number of SPS injections using different assumptions on SPS loss pattern, can we use lower current from LEIR but over a shorter cycle -using the 100ms injection-, improvement to the gaps for MKI and MKD in the LHC etc.) - Action: Giovanni to talk with John and identify who could follow this up systematically
- Need follow up on IBS/Touschek studies in the SPS with ions - Action: Giovanni to talk with Yannis who will take over this task after Fanouria's departure (could be the same person that makes optimisation of the injection schemes for luminosity production from the previous point)
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