Minutes of the LIS Section meeting held on 14th March 2011

Present: G. Arduini, S. Aumon, H. Bartosik, C. Carli, S. Gilardoni, A. Lachaize, M. Martini, Y. Papoaphilippou, G. Prior,  M. Newman

General Information (Gianluigi)

Erk Jensen will be new BE/RF group leader from 1st July

No request for Spanish students or staff child projects has been received

Christian and Gianluigi have discussed with I. Sakai (Kyoto University) about the possible visit of one of his collaborators (K. Okabe) for 6 months. K. Okabe cold work on the conceptual design of a collimation system for the PSB. He could first spend some time at J-PARC to understand their system and then could apply that experience to the PSB. Christian will ask  funds to R. Garoby.

LHC

The commissioning is progressing well. The beta beating correction was successful and beta beating lower than 10% have been achieved. Stable beams with 3 nominal bunches against 3 nominal bunches have been achieved with luminosities in excess of 1030 cm-2 s-1. Ramp up in intensity will continue during the week.

The final programme of the IEFC WS (21-24/3) is available at: http://indico.cern.ch/conferenceOtherViews.py?view=standard&confId=1235

MTE for PS2 (Antoine) - slides

Christian asked whether the phase space at the magnetic septum optimized. Antoine replied in the affirmative. Christian noted that the clearance at the septum could be further increased if the phase space is rotated. Optimization has been done w.r.t. the strength of the octupoles and sextupoles and then with respect to the duration of the crossing of the resonance (optimum is 40-50 thousands of turns). This is a number of turns similar to the PS. The transverse feedback could be used to further increase the capture efficiency in fact the estimated capture efficiency does not include the effect of synchrotron motion and chromaticity. It is not clear why the vertical emittance is smaller than the initial one (70 %). Gianluigi asked whether a spoiler is required to protect the septum. Antoine replied that the quoted losses are all around the machine and not necessarily at the magnetic septum. It must be checked at which location these occur.

Attempts of reducing the chromo-geometric terms is ongoing. Yannis suggested to introduce the magnetic errors before doing such a detailed study. The effect of magnetic errors is probably no negligible because they have a significant effect on dynamic aperture at injection reducing the dynamic aperture to 5 to 6 sigmas which corresponds to about 15-20 sigmas at top energy.

Losses at PS Injection (Sandra) - slides

An aperture model has been built for the injection line. The beam must be injected off-centre and close to the injection septum because of the limited strength on the kicker. It is not possible to increase the strength of the present kicker. A re-matching of the line to minimize the beam size at the injection septum would require more strength (~factor 2) in at least two quadrupoles of the injection line. This could be increased by adding two other quadrupoles close to two existing one. This option should be investigated as quadrupoles and power converters might be available and this could minimize losses while waiting for the PS upgrade. The optics of the ring should be also modified at the injection region in order to preserve the matching of the line to the ring. This would require the use of the QKE quadrupoles. Losses continue for some time after injection and are likely due to tail repopulation due to space charge. Synchrotron motion and high chromaticity could make worsen the losses. A tune and chromaticity scans are ongoing.

Round Table (all)

Simone

POPS is running well but noise is observed on the Bdot signal.  The 50 and 75 ns beams are ready. The transverse emittance of the 25 ns beam needs to be checked. It has not been tried yet to increase the intensity on 75 ns above nominal. The 2 Basic Period cycle for MTE is not working yet (there is an issue with RF tree). The programme for the correction of the 5 turns for the CT or MTE extraction has been debugged and corrected. It will be tested with the CNGS beam next week. It should work now.

Gersende

A new version of MARS is available. It must now be checked whether the difference that we had in the past between BNL and CERN versions is still there. Furthermore the simulations are giving smaller values than those expected by HARP data. The latest version of MARS should take into account HARP data. The Intermediate design report is being reviewed. Gersende is helping on that.

Hannes

Orbit-PTC code. The synchrotron motion is now correct. This was due to an incorrect definition of the RF parameters.

Michel

Michel has been working in assessing the possible use of the TSU (Heidelberg) ring for storing  ions for beta beams.

Next meeting

Monday, 28th March 2011 at 14:00 in room 354-1-001

Agenda

 

 

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