Minutes of the LIS Section meeting held on 15^th October 2007.

Present: G. Arduini, S. Aumon, J. Barranco, E. Benedetto, O. Berrig, C. Carli, M. Chanel, A. Franchi, S. Gilardoni, M. Juchno, M. Martini, E. Métral, Y. Papaphilippou, D. Quatraro, G. Rumolo, B. Salvant.

General information (G. Arduini)

F. Bordry will be the new Deputy Department Head starting from 1/1/2008.

J.-P. Matheys  will be the new ADM group leader starting from 1/1/2008.

Beam 07: Discrepancies are observed between measurements and ORBIT simulations for SNS. The imaginary gamma transition lattice solution for PS2 seems to take consistency. Concerns were expressed during the workshop concerning the lack of operational experience with machines with imaginary gamma transition. C. Carli reminded that LEAR had an imaginary gamma transition. The status of the SPS impedance model and of the electron cloud studies were given at the workshop.

E. Métral has conducted a preliminary study on the transition crossing in the PS2 (draft). A first conclusion is that at least 3 to 5 larger longitudinal emittance would be required to cross transition in the optimistic assumption that only space charge impedance is considered.

Ultimate beam (E. Métral) - slides

E. Métral presented some considerations on the Ultimate LHC beam that he outlined during the BEAM07 workshop, the basic argument being that larger emittances from the PS-Booster might imply smaller absolute blow-up in the downstream machines. A re-optimization of the nominal transverse parameters might be therefore necessary. The 48 bunch scheme proposed last year could further help in achieving ultimate performance. A test to compare 48 vs 72 bunch scheme is planned.

Final report on ANSYS magnet model study (M. Juchno) - slides

TMCI studies in the SPS: results of the observations (B. Salvant) - slides

The data for the TMCI instabilities have not been fully analyzed yet and a new machine development session is planned for the end of the end of the month. Measurement will be taken at injection and with matched voltage to avoid strong quadrupolar oscillations.

Status of the machines

SPS (E. Métral) - Week 40

PS (S. Gilardoni)

Tune measurement seems to work (at least for small radial positions) for short bunches. Tests are still ongoing.

PSB (M. Chanel)

Tune measurement seems to work now.

Ions (G. Arduini, C. Carli)

A new optics for the TT2-TT10 transfer line has been loaded and it provides a good matching. No tails are observed and emittances seem to be preserved. The beam has been accelerated through transition in the SPS. Signs of bunch shortening and of reduction of the bunch peak intensity have been observed at flat-bottom. E. Métral has suggested to verify whether this could be due to Touschek. Gianluigi made a preliminary estimate and it seems that the Touschek lifetime is very large (hours).

Losses are still observed in the PS (~50% of the beam) and the reason needs to be found.

Next meeting

Wednesday, 14^th November 2007 at 09:00 in room 6-2-008

Agenda

General information (G. Arduini)

Status of the machines (supervisors)

Status of Machine Studies (E. Métral)

A.O.B.

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