Minutes of the LIS Section meeting held on 11th April 2011

Present: G. Arduini, H. Bartosik, C. Carli, A. Lachaize, M. Martini, G. Prior

General Information (Gianluigi)

Fellow requests should be sent to Gianluigi by the end of the week.

IPAC11: The abstracts approved by Paul should be submitted by 13/4.

The long term scientific plan has been discussed in a meeting organized by the DG. The first long shut-down will last 2 years (from beam to beam). The running period between two consecutive shut-downs should last 3 years. The first shout-down might start (CMS proposal) in March 2013. The third shut-down when the modifications related to the High Luminosity LHC upgrade should be implemented should take place in 2022 according to the above scheme.

PS impedance: data taken in 2001 (Elias et al.) for the detuning with intensity seem to be consistent with the data collected by S. Aumon in 2010.

LHC (latest news at: https://lhc-commissioning.web.cern.ch/lhc-commissioning/news-2011/LHC-coordination-2011.html): the recovery from the technical stop has been tedious due to various problems (delays in the recovery of the cryogenics, earth fault on a trim quadrupole circuit). Following the realignment of three collimators loss maps had to be repeated and evidenced a loss of hierarchy in the horizontal plane for Beam 1. This seems to be related to a loss of margin in the orbit excursion.

Scrubbing with 50 ns beam has started on Wednesday 6th April but it had to be stopped for two days on Thursday morning after having detected a cabling error in the protection of one the 13 kA current leads leading to a loss of redundancy. Investigations during Thursday and Friday revealed that no other high current circuit had a similar problem and scrubbing could resume.

On Sunday 1020 bunches (trians of 72 bunches) could be injected in the LHC representing the highest current injected in the LHC at 450 GeV. In spite of the interruptions the scrubbing is progressing well and a test ramp should take place tomorrow or on Wednesday to qualify the effectiveness of the scrubbing at 450 GeV for operation to 3.5 TeV. If the effectiveness of the scrubbing is confirmed we might continue scrubbing.

Round table (all)

Antoine

There are still some issues with the correction of the 5 turns form the CT. There is a good fit for turn 1 and 2 while the fit is more difficult for other turns. Gianluigi suggested to verify whether the measured data refer to the first turn.

Gersende

Comparison of the MARS data at CERN and BNL: The BNL runs are complete now and the results must be checked with those from CERN runs. The code is the same but seeds might be different.

Gersende is working with the student of Ilias Efthimiopulos to optimize of the capture efficiency by adapting the tapering of the solenoids after the target. Gianluigi suggested to read some of the papers of S. Van der Meer on the subject of the neutrino horn where analytical approaches could be found and could be used to guide the optimization process initially.

Christian

Christian is reviewing the layout of the LINAC4 to PSB transfer lines. A few issues have been identified in the present layout. The power converters for the magnet of the transfer line have already been ordered but some limitations in the maximum strength of the magnets have been identified.

Christian has organized a second meeting to determine the feasibility of extracting ions from PS to the East Hall for radiobiological studies. This preliminary study should be completed rapidly to determine whether such experiments could be performed already next year.

A web version of the Chamonix Proceedings is available on the web.

A summer student (non-member state) will join LIS to study the injection of 50 MeV protons from LINAC4 in case of a failure of LINAC2.

Hannes

The issue of the discrepancy between ORBIT-PTC and Laslett formulas in the estimation of the indirect space charge tune spread has been understood.

Head tail simulations have started to determine the effect of the lower gamma transition on the electron cloud instability threshold for the 25 ns beam

Next meeting

Monday, 9th May 2011 at 14:00 in room 354-1-001

Agenda

 

 

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