Minutes of the LII Section meeting held on 15^th May 2006.

Present: G. Arduini, S. Aumon, G. Bellodi, O. Berrig, C. Carli, R. Bruce, M. Chanel, H. Haseroth, J. Jowett, M. Martini, S. Maury, J. Pasternak, F. Roncarolo, G. Smirnov.

PS Booster start-up status  (M. Chanel) (slides).

No major problems during the start-up, some difficulties related to controls and in particular with the Beam Current Transformer due to the migration to FESA. The Linac 2 current is limited to 130-140 mA. This is partly due to the short pulses which are required from the Linac as ISOLDE is not requiring high intensity. PSB Ring 3 still shows a poorer performance as compared to the other rings. Another feature is the capture at a radial position of about +6 mm in order to have optimum performance on ring 1.

Investigation of aperture limitations by the PS horizontal wire scanners in straight sections 54 and 64 (O. Berrig) (slides)

A detailed model of the PS aperture is now available to determine possible aperture bottlenecks for the different beams and optics in the PS. The observation in 2003 and 2004 of tails in the beam profiles measured with the wire scanners in the PS for high intensity beams has triggered a detailed study of the aperture in the regions close to the wire scanners. The horizontal wire scanners and the measurement target (a scraper used for transverse amplitude distribution measurement) could be aperture limits in the horizontal plane because the minimum horizontal size of the vacuum tank is smaller than the horizontal size of a standard vacuum chamber. No evident limitation has been observed at injection and at extraction (CT and fast extraction).

Status of the gamma jump study in the PS (S. Aumon) (slides)

The issue of the aperture at the wire scanners has also been analyzed for the gamma jump. A potential bottleneck has been identified at WS64 and at the measurement target 65. Solutions are being investigated.

PS start-up status (S. Gilardoni) (slides)

The start-up was pretty smooth so far and the realignment campaign was very successful. Pending problems:

• wire scanners. None of the working at the beginning. Potential damage to H54. H64 not working yet.
• the behaviour of the extraction bump in 16 is not yet understood. Doubts on the beam position readings and on the value of the current flowing in the magnets.
• Important orbit distortion have been observed during transition. That could also be the result of a momentum offset variation during transition crossing.
• Some controls problem (OASIS in particular).

Next meeting and tentative agenda

Monday, 19^th June 2006 at 09:00 in room 6-2-004

General information (G. Arduini)

Orbit error implementation in ICOSIM (H. Braun)

Electromagnetic interactions for channeled ions (G. Smirnov)

Status of the LINAC4 studies (M. Martini)

Gamma jump in the PS: status (S. Aumon)