Summary notes of the LCU meeting on 10/08/2010

Present: OB, HB, RC, OD, MF, MG, YL, MS, RT, FZ, Kazuhito Ohmi, Chandrashekhara Bhat, Tom Mertens

Report from meetings

• General information -> MG
  MG started to welcome new members and visitors:
  technical student Tom Mertens, who works with JJ on heavy ions.
  Chandrashekhara Bhat who is working on injectors upgrade
  Kazuhito Ohmi who is working on beam-beam and e-cloud.
  The LHC is running well. Most of the running is for physics with 25 bunches per beam. The peak luminosity reached 4.e30cm-2s-1. Beam-beam tune shifts from central collisions have reached and even exceeded the nominal values without problems. Several fills were suddenly lost in stable physics. The loss patterns and possible explanations are currently studied with help from our group on aperture modeling (CA) and dust particles simulations (FZ).
  MG reports that the error tables generated with WISE and FiDeL corresponding to the LHC machine as-built will be stored in the official afs optics repository for tracking use.
  Ezio Todesco is reviewing the LHC settings and the magnet modeling. Several questions and possible issues came up in this context and will be followed up:  Skew sextuples were active since the 21 May and it will be checked if this is intended and useful. The correction was implemented by MS, who translated the algorithm prepared by SF for tracking simulations.
  The decrease of magnet ramp rates in the last technical stop resulted in modified dynamical behavior. Horizontal and vertical tunes now change in opposite direction during the ramp for the two beams.
  The MCD were found weaker by a factor of 2 for a couple of months. This has been fixed.
  The MCO are powered to a few Amperes at injection. Due to the strong magnetisation, this induces a sort of undefined status of the correctors, some under correcting and some overcorrecting the b4 component in the dipoles. Overall, the compensation is correct and the MCO will be kept in operation.
  Landau octupoles are used at top energy and it remains to be checked if they are still useful in presence of collisions and operation with the transverse damper on. FZ suggested to use the octupoles to reduce the tune spread from the beam-beam interaction.
  The Q33.L2 was found displaced by 1 mm in the horizontal plane: the causes for this are being checked. Aperture is also being verified (CA).
  The organization of the LHC upgrade studies will evolve from a task force to a project lead by Lucio Rossi with OB acting as deputy.  Several of us are involved in this work. Work packages are being defined and organized with collaboration from outside CERN (USLARP). FZ mentioned also the FP7 supported activities within EUCARD (e.g., ACCNET). C. Bhat said that  single bunch intensities of 3.6e11 protons were reached in the SPS. MG said there is furthermore promising work in progress on the SPS optics which should allow to decrease transition, which increases stability thresholds at injection into the SPS.
  
• LMC -> FZ
  The last LMC was dedicated to a discussion how to arrive at the planned 1.e32cm-2s-1 luminosity this year. It was decided to stay at the current beta* = 3.5 m and increase the luminosity by increasing the number of bunches. Two options for the bunch spacing, 75 and 150 ns were discussed. 150 ns would be preferred by the experiments. It is now for the injectors to verify that 150 ns could be provided with similar intensities and emittances as for 75 ns. More details can be found in the LMC minutes.
  

AOB

None

Last update: 10-August-2010

MG & HB

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