Minutes of the LIS Section meeting held on 14^th May 2007.

Present: M. Aiba, G. Arduini, O. Berrig, C. Carli, M. Chanel, A. Franchi, F. Gerigk, M. Juchno, M. Martini, S. Maury, Y. Papaphilippou, G. Rumolo, B. Salvant, G. Smirnov, F. Zimmermann.

General information (G. Arduini)

A group meeting will take place on 31^st May (the date was changed after the meeting  to 1^st June).

The proposal for the space charge studies in the frame of LARP has not been accepted for this year but FNAL management is supporting a collaboration with us. The FNAL colleagues (M. Popovic) asked when would it be the best period (after 4th July) to come at CERN to participate to the machine studies on space charge at the PS Booster. Action: M. Chanel and C. Carli to propose the dates. 

The option of a Rapid Cycling Synchrotron as PS2 injector has been discarded by the SPC. The SPL is now the favorite option. C. Carli noted that there was not much time for the study of the RCS option.

Follow-up of ACCSIM-ORBIT benchmark (M. Aiba) - slides

There is a good agreement between ORBIT and ACCSIM for the case of linear tracking in the horizontal plane, the same is not true for the vertical plane where a discrepancy is clearly visible for the r.m.s. and 100% emittances after 1000 turns. The discrepancy can be observed both for the linear and non-linear tracking.

The option of non-linear tracking is not documented. Y. Papaphilippou suggested to contact J. Holmes. Action: M. Aiba to contact J. Holmes and S. Cousineau to get additional documentation on the non-linear tracking.

The tune footprint still show some points with significant tune offsets with respect to the expected spread even in the absence of space charge. The main discrepancy occurs in the horizontal plane. This could be due to the algorithm used to calculate the tune in ORBIT.

G. Arduini suggested to study the emittance evolution without space charge for ACCSIM (already done) and ORBIT for the linear and non-linear case. In ACCSIM no emittance blow-up is observed in that case. Y. Papaphilippou noted that in the case of non-linear tracking emittance blow-up could be observed due to the non-linear part of the fringe field in dipoles. Action: M Aiba to study the evolution of the emittance in the absence of space charge for the linear and non-linear tracking. A tune scan might be necessary for the non-linear case to avoid resonances.

Follow-up of ACCSIM-ORBIT benchmark (M. Martini) - slides1 - slides2

Status of the LINAC4 site study (S. Maury) - slides

(G. Arduini for M. Chanel).

The major problem is the orbit acquisition:  beam position is read even without beam. The problem is not yet understood and this is delaying the beam-based realignment of the PSBooster.

Status of the PS (S. Gilardoni, Y. Papaphilippou)

Main beams (SFTPRO,EAST, AD) have been prepared (at least at moderate intensity. Some more work is required for the optimization of the slow extraction, but for the time being the beam is not extracted to the East because of a vacuum problem in the East Area.

There is a problem with the controls of the PFW (operated in 5-current mode simulating the old 3-current mode of operation) generating frequent trips of the power supplies. A

Next meeting

Monday, 11^th June 2007 at 09:00 in room 354-1-001

Agenda to be defined

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