Minutes of the LIS Section meeting held on 19^th March 2007.

Present: M. Aiba, G. Arduini, J. Barranco, G. Bellodi, E. Benedetto, O. Berrig, C. Carli, M. Chanel, A. Franchi, S. Gilardoni, M. Juchno, A. Lombardi, M. Martini, Y. Papaphilippou, G. Rumolo, B. Salvant, G. Smirnov.

General information (G. Arduini)

• Workshop ECL2 (WS on e-cloud clearing) - 1-2/3/2007 (http://care-hhh.web.cern.ch/CARE-HHH/ECL2/default.html) No progress in the characterization of the materials from the point of view of SEY and reflectivity. The following issues were raised and needs an answer.
  • NEG (when conditioned) and TiN seem to have equivalent SEY (Secondary Emission Yield).
  • NEG: does it maintain low SEY after venting? how many times can be cycled (venting and conditioned) without significantly loosing its low SEY? Impedance of NEG coated surface? Problems at high frequency?
  • TiN: low SEY even after venting?  Stability with time?
  • Enamel: will the enamel charge up and then spark?
  • Clearing electrodes: simulations simulate the case of constant voltage during beam passage. But normally there is a voltage drop during the beam passage.
  • TS/MME (P. Chiggiato) are interested to compare NEG and TiN (or ZrN). Possible installation of a NEG and TiN or ZrN chamber in the SPS in 2008?
• L. Rinolfi will take over from M. Martini as Member of the Academic Training Committeee, Applied Physics WG
• DOE seems not to support a strong R&D programme towards ILC in the medium term

Linac 4 to PSB transfer line (G. Bellodi) - slides

The following points came out from the discussion:

• the vertical dispersion and its derivative should be 0 at the entry of the PSB distributor.
• the sign convention for the dispersion needs to be verified (Action: G. Bellodi, C. Carli)
• the values of the horizontal dispersion and its derivative cannot be constrained at present and certainly depend on the final choice of the painting scheme (in particular in the longitudinal plane)
• it is not clear whether the Twiss parameters at injection used in the simulations so far correspond to the values assumed in the calculation of the injection line (Action: G. Bellodi, M. Martini).
• the choice about the longitudinal painting scheme can be done only based on space charge simulations. M. Martini will try to simulate case 2 (in Giulia's slides) with ACCSIM: input files for each turn are required as input from Giulia. The nominal LHC beam case will be studied. Action: G. Bellodi, M. Martini.
• the HW for the energy ramping seems to be feasible
• Giulia will study the so-called case 4 ("relaxed" energy ramping without debuncher)
• A study of the tunability range of the line seems to be very heavy at this stage. The possibility of tuning the horizontal dispersion and its derivative either at 0 or at the values of the PSB at injection (dispersion matching) could give an indication of the tunability (at constant Twiss parameters and for vanishing vertical dispersion and deispersion derivative).

Next meeting

Monday, 2^nd April 2007 at 09:00 in room 354-1-001

Agenda

General Information (G. Arduini)

Space charge effects for CNGS beam at 160 MeV in the PSBooster (M. Martini)

PS space charge benchmark (E. Metral)

First comparison of ORBIT and ACCSIM (M. Aiba - to be confirmed)

Back to Minutes