Minutes of the LIS Section meeting held on 25^th March 2013

Present: Javier Alabau, Androula Alekou, Fanouria Antoniou, Gianluigi Arduini, Hannes Bartosik, Elena Benedetto, Michael Bodendorfer, Christian Carli, Vincenzo Forte, Adriano Garonna, Simone Gilardoni, Alexander Huschauer, Guido Sterbini, Letizia Ventura, Raymond Wasef

General Information (Gianluigi)

Beam-Beam WS took place last week: http://indico.cern.ch/conferenceOtherViews.py?view=cdsagenda_olist&confId=189544

Space charge WS will take place from 16^th  to 19^th April: link. http://indico.cern.ch/conferenceDisplay.py?confId=221441

Gianluigi has informed Elias about the issues with ORBIT-PTC reported by Raymond last week . He will follow that up with Frank.

Doctoral student requests to be sent to Delphine with copy to Gianluigi by 2/4 (the template will be circulated by Delphine).

New structure for radiation protection courses. Gianluigi has circulated the corresponding MEMO by e-mail.

Status of the studies on the PSB Inconel Vacuum Chamber in the injection region (Elena) - slides

This is a preliminary report on the effect of the installation of an inconel vacuum chamber in the PSB chicane magnets instead of a ceramic vacuum chamber with metallic coating. This has implications on the multipolar components seen by the beam during injection.

On top of the injection chicane bump the painting bumps will be active but over a shoter time scale (up to 100 us) and using existing magnets under vacuum. The decay of the chicane bump is 5 ms. During all the injection process the beam will not be centred on the centre of the inconel vacuum chamber.

Gianluigi and Christian were puzzled about the evolution of the sexrupolar component (e.g. it was not clear why the sextupolar component did not vanish at the end of the decay of the chicane bump.

For the simulations a standard LHC beam with 1.65×10¹².p was used with a transverse emittance of 2 mm (H) and 1.5  mm (V).

It is not clear why we get a reduction of the vertical blow-up including the multipoles. It would be important to study the machine lattice without space charge.

Christian asked whether there is any cross talk between the magnetic fields of the various bumpers. Elena will verify that with the ABT colleagues.

The PTC-ORBIT simulations have been done with the parameters found in the convergence studies by Vincenzo and Sasha.

Status of the measurements at LEIR low energy (Michael) - slides

The measurement of the momentum offset is based on YASP. Simone asked whether the model in YASP (dispersion) is consistent with the measured dispersion. This.needs to be checked (Michael to verify that) The revolution frequency could be used as the the slip factor eta is dominated by the 1/gamma^2 term an therefore it is not necessary to know precisely the momentum compaction factor.

Christian asked whether the losses observed at low energy are related to the RF capture. Michael replied in the affirmative.

Simone suggested to check with Marek whether the losses are affecting the tune measurements.

Only the horizontal chromaticity data have been analyzed. The vertical data need to be analized ==> Michael.

Round Table (all)

In the previous meeting Raymond also reported that different final distributions are obtained when running simulations having the same parameters and the same initial distribution. This difference disapeear if only one processor is used. This will be reported to the space charge WG meeting and could be tackled with J. Holmes after the space charge workshop.

Monday, 22^nd April 2013 at 14:00 in room 6-R-012

Agenda:

General information (Gianluigi)

Round Table (all)

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