Minutes of the LII Section meeting held on 13^th November 2006.

Present: G. Arduini, J. Barranco, G. Bellodi, O. Berrig; R. Bruce, C. Carli, M. Chanel, J. Jowett, S. Gilardoni; M. Juchno, M. Martini, S. Maury, Y. Papaphilippou, G. Smirnov

General Information (G. Arduini) - slides

Since the last meeting the date of the Christmas party has been changed (12th December).

Status of LEIR and PS ion commissioning (C. Carli and M. Martini) - M. Martini's slides.

LEIR start was delayed due to vacuum problems in the electron cooler but the Early ion beam was very rapidly obtained and the PS Ion Commissioning could start with only minor delays. Emphasis was given to the commissioning of the PS with the Early Ion beam. In parallel work with the nominal beam was performed and 80% of  the nominal intensity achieved at high energy with nominal intensity injected. Losses were observed at the beginning of the ramp. Instabilities have been observed. Damper, and RF digital controls are still evolving and this might be at the origin of the observed losses.

Matching LEIR-PS: one iteration initially reduced the mismatch in the H-plane but found some vertical mismatch. Suffered from problems with SEM wires at injection. Still controls problems with the SEM wires in the LEIR ETL line..

Early beam sent to the PS was obtained with only one pulse from Linac3 (20-25 microamps). Found some settings that can give Pb²⁹⁺ with higher intensities as compared to Pb²⁷⁺ and lower X-ray emission.. This would allow running Linac3 at 5 Hz.

Some scrubbing has been observed in LEIR at the beginning of the run. No clear effect of the electron-cooler on beam lifetime has been observed. The average residual vacuum pressure was higher (~1-2 x 10^-11 mbar) than during the run in spring. The average pressure should be in the range of few 10^-12 mbar.  The effect of the collimators on the residual vacuum and lifetime has not been studied.

The power converter feeding the quadrupole QFO215 has not been upgraded as required and its maximum current was therefore limited to 330 A. For that reason the minimum beta function at the stripper was limited to ~8-9 m instead of 5 (nominal). In spite of that the r.m.s. normalised emittance has been measured to be 0.7 (H)/0.6(V)  mu.m for the early beam after the stripper. This is smaller than the nominal value for the Early beam (1 mu.m) in both planes. The emittance blow-up due to the stripper could be measured for the 8 m low-beta optics and it amounts to 0.15 mu.m to be compared to the expected value of 0.12 mu.m. The emittance blow-up measured with the LHC proton optics was measured to be 0.4 mu.m.

The Aluminum stripper thickness during the test was 0.8 mm. It is not possible to test different stripper thicknesses as this would require opening the vacuum.

Optics measurements have been also taken without QKE58 (the powering of this quadrupole doublet in the PS will be suppressed in the first part of the 2007 run). The next MD is dedicated to load the optics re-matched to take into account the absence of QKE58 and to study the mismatch at injection.

Shielding of the PS pick-ups - estimated effect (preliminary) (J. Barranco) - slides.

The exact position of the shielding might need to be verified.

Round Table

J. Jowett mentioned that he gave a presentation on "Plans for Heavy Ions in the LHC" at one of the PAF meetings (http://paf.web.cern.ch/paf/) on 9th October 2006  (http://paf.web.cern.ch/paf/Presentations/HI_in_LHC_JJowett_Oct2006_v2.pdf).

Next meeting

Monday, 11^th December 2006 at 09:00 in room 6-2-004 (please note unusual place)

Tentative agenda

General Information (G. Arduini)

Optics studies for the LHC beam in the TT2-TT10 line and effect of the QKE58 suppression (E. Benedetto)

Common repository for the aperture and optics files for the PS-SPS Complex (O. Berrig)