Minutes of the LIS Section meeting held on 7^th April 2008

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

General Information (G. Arduini)

Open days were a success. Thanks to everyone involved.

White paper posts: AB is going to submit a request for 40 to 50 posts for decision (by the CFO) sometimes in the second half of the year.

The requests for a staff child has been submitted. We should get one in summer (under Lauriane supervision) to scan old notes. Suggestions for possible notes to be scanned are welcome.

Non-ultra-relativistic resistive wall wake fields (D. Quatraro) - slides

Diego presented the first results of the analysis of the non-relativistic resistive wall wakes. The analysis is based on the formalism developed by Oide and Zimmermann and has been conducted in particular for the study of the wakes propagating ahead of the non-relativistic bunch while Oide and Zimmerman mainly focused on the trailing part of the wake. The analysis has been conducted so far for the longitudinal wake and it has just started for the transverse plane. The study of the transverse behaviour in the case of a wake field coupling the tail to the head of the bunch has been conducted by a considering for the moment a simplified two-particle model and shows already an interesting feature: the stability diagram show a stability island going to higher intensities when the forward-propagating wake is taken into account.

Gianluigi noted that these studies are of importance for understanding the beam dynamics in the PS Booster but it seems also that they could be of interest for the PS. It will be very important to continue the analysis also in the transverse plane although Diego, Elias and Giovanni pointed out that this is much more difficult in the transverse plane.

Elias asked whether a comparison with Benoit-Elias formulas for the longitudinal resistive impedance has been done. Diego replied that this has not been done yet.

Simulating transition crossing in the PS with HEADTAIL (B. Salvant) - slides

The HEADTAIL code has been modified in order to include acceleration and therefore transition crossing.

Some tests have been conducted by Benoit to test the code and benchmark it against analytical formulas calculated by Elias and to conduct a preliminary study of the instability developing at transition crossing in the presence of a broad-band impedance.

Experimental studies and simulations (with HEADTAIL) will be conducted during the run to study the behaviour of the beam at transition in the PS. Sandra will conduct these studies.

The gamma jump is not yet included in HEADTAIL as well as alpha_2.

Yannis asked whether there is a dependence of the instability growth time on the gamma transition. Elias replied that he had looked into that, but he has to look again at the conclusions.

Round table

A web page has been set-up by Benoit and Elias for the SPS impedance studies and a link has been created from the LIS web page. Bruno Spataro has provided the tables describing longitudinal and transverse impedances vs. frequency for the horizontal and vertical beam position monitors resulting from MAFIA simulations. He will now finalize the analysis for the vacuum ports. Elias is trying the drawings for the 800 MHz cavities and some additional drawings for the SPS wire scanners.

MKDV1/2 (beam dump kickers in the SPS). L. Ducimetiere has provided the dimensions for the apertures of these two kickers. Giovanni should now launch some simulations to compare the electron cloud build-up for these two apertures. Action: Giovanni

The cabling for the new pick-up for the PS tune measurement has not been completed yet. (after the meeting: done).

The cabling of the new doublets of the PS gamma jump has not been modified as required to allow independent powering of the two brunches of the gamma jump quadrupoles in order to keep open the possibility of re-installing the old power converters in case of problems. The final cabling should be done during the next shut-down. Simone will follow that up with Ray. Action: Simone.

There are still problems in reading the raw data taken last year with the new BBQ tune measurement. Simone and Yannis are in contact with Ralph. Yannis will present the results of the analysis at the next Section meeting.

A bug has been found by Olav and Frank in MADX in the treatment of maps for dipoles. It has been corrected.

R. de Maria is going to work on PS2 and he is going to provide a web tool to access the PS2 optics.

A PS2 internal review is planned for 29/5.

Javier mentioned that the simulations for the PS Continuous transfer are completed and a note is in preparation.

Elena mentioned that the analysis of the data taken with the SPS matching monitor is ongoing and a fast filamentation is visible.

 The issue of a possible scheme for the AD production with 5 bunches will be discussed at the APC in April.

Gianluigi asked what is the status of the note on the LHC ion optics in TT2-TT10. Michel replied that the note is being written. Gianluigi reminded that it is important to finalize it as soon as possible so to make it available as supporting documentation for the optics available in the common repository. Action: Michel.

Gianluigi asked the supervisor to circulate to the colleagues in the section and to Oliver and Simon the mail which is normally sent to Paul during the week-end concerning the status of the machines so to spread the information and concentrate on the most important issues during the section meeting.

Gianluigi proposed to change the starting time of the meetings from 9 to 10:30.

Next meeting

Monday, 21^st April 2008 at 10:30 in room 354-1-001

Agenda

General Information (Gianluigi)

Analysis of the raw data taken with the tune measurement in 2007 (Yannis)

A.O.B.

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