Minutes of the LIS Section meeting held on 23rd May 2011

Present: G. Arduini, H. Bartosik, G. Bellodi, C. Carli, S. Gilardoni, A. Lachaize, M. Martini, B.. Mikulec, G. Prior.

General Information (Gianluigi)

The ABP group meeting will take place on Tuesday 28/6 and it will be followed by a barbecue (weather permitting).

LHC: progressing well, injected up to 912 bunches and a luminosity of 1.1×1033 cm-2s-1 has been achieved.

 

Status of the LINAC4 to PSB beam dynamics studies and open questions (Christian) - slides

Changes in the layout of the transfer line between LINAC4 and PSB are being finalized in order to match the characteristics of the power converters (already ordered) to those of the magnets (design just completed). Bettina asked whether there is any potential interference with the planned beam instrumentation. Christian replied that this should be verified. The magnets that will be built will be rectangular magnets while in the past it was assumed that they were sector magnets. That is another reason for review of the optics. Solution of the optics with matched D and vanishing dispersion at the injection point have been proposed.

Bettina asked whether the line should still be able to go to pulse with a repetition period of 900 ms. Christian replied in the affirmative, but it must be verified.

A margin of 15 % in the maximum strength has been assumed for the new layout.

Christian pointed out that original design of the transfer line was including 14 trajectory correctors but only 5 magnets and power converters have been considered by the magnet and power converter teams. Christian is going to verify the reason for this discrepancy.

Space charge effects (including optimization of the longitudinal painting) are being evaluated at injection with the help of Jean-Baptiste Lallement.

The effect of magnetic imperfections of the chicane magnets on the beam quality after injection should be urgently evaluated taken into account the large amplitude of the injection chicane bump amplitude (45 mm).

Time dependent properties are not yet implemented in ORBIT-PTC. Etienne and Sasha are still working on it.

Collimation and activation issue should be urgently addressed. Kato Okabe (Kyoto University -J-PARC) has not confirmed his visit after the earthquake occurred in Japan.

The specifications for the injection hardware are quite advanced and the impact of the installation of the equipment on machine impedance should be evaluated..

Gianluigi pointed out that commissioning strategies and tools should be developed (e.g. resonance terms measurements and compensation).

Michel pointed out that Sasha could be interested in spending one year at CERN as scientific associate.

 

Round table (all)

Gersende

A summer student is going to work on the neutrino factory (possibly on the parameters data-base)

Simone

Transverse emittance measurements with wire scanners in the PS are not sufficiently precise because the resolver ADC has not sufficient resolution..

Work is still ongoing to understand the origin of the oscillation in island positions measured with the turn-by-turn BPMs. Saturation has been observed in some BPMs but no warning is issued by the orbit acquisition system. Simone is trying to calibrate the BPMs and verify the amplitude at which they saturate by calibrating them imparting a known kick.

Simulations are ongoing to determine the settings for the extraction with the electrostatic septum SEH31.

Hannes

Measurements of the transverse emittance as a function of intensity: are being performed and for the moment a linear dependence has been observed with an emittance of 2.5 um for a bunch population of 2.5x1011 p.

Blow -up has been observed in the SPS and it is mostly occurring at the flat bottom.

Elena Benedetto is conducting a similar scan in the PS.

 

Next meeting

Monday, 20th June 2011 at 14:00 in room 6-R-012

Agenda

 

 

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