Minutes of the LIS Section meeting held on 11^th August 2008

Present: G. Arduini, J. Barranco, E. Benedetto, C. Carli, M. Chanel, A. Franchi, S. Gilardoni, E. Métral, Y. Papaphilippou, D. Quatraro, G. Rumolo

General Information (Gianluigi)

The synchronization test has been successful. The LHC beam went immediately to point 3 on the first shot.

Dispersion and kick response analysis indicate some optics errors in the machine. Investigations are ongoing to identify the source of these problems.

A new Committee, the LHC Performance Committee,  has been set-up replacing the LHC Technical Committee and the LHC Installation and Commissioning Committee.

PS & MTE status (Simone) - slides

Extraction of the 4 islands and the core performed on 01/08.

Capture with 18-19 % efficiency in the island obtained without losses.

Major issue is the reproducibility of the capture on a cycle-by-cycle basis. No significant noise has been measured on the non-linear element currents. Measurements will be performed on the Pole-Face Windings and on the Figure of eight loop during the week.

The longitudinal setting-up of the beam is not yet completed and the longitudinal structure is not reporducible at high energy.

Gianluigi asked whether the non-reproducibility is observed also at lower intensity, e.g. with SFTPRO like beams. Simone replied that for these beams the instability is still there but it is less dramatic. Gianluigi suggested to focus on the SFTPRO beam and to try to deliver it to the SPS in order to gain operational experience. Given the lower intensity the SPS should be more tolerant to any intensity variation along the spill.

It might be also good to make some tests with capture with RF off in order to disentangle the effect of the longitudinal structure on the reproducibility of the capture.

The setting-up of the MTE on a 1 basic period cycle is ongoing.

Simone reported also on the failure of the spark gap protection for the main power supply.

Measurements of orbit and dispersion confirm that the quality of the orbit measurement is now good. It has been decided not to re-align the machine.

Highlights from  EPAC08 (Elena) - slides

Elena presented some of the latest achievements on:
Crab cavities at KEKB
Last year of PEP II
Electron lenses at Tevatron
Plasma wake-field accelerators

Only one crab cavity is installed at KEKB therefore the beam performs head-tail oscillations all around the ring. The peak luminosity and beam-beam tune shift have increased but a lower lifetime has been observed so that no increase in integrated luminosity has been observed so far.

The electron lens at the Tevatron is pulsed on one bunch only resulting in an enhancement of the lifetime of that bunch. During he meeting it was not clear why the electron lens is not pulsing on the other bunches.

Round-table (all)

PS

The HV cable of the electrostatic septum 31 had to be changed again. There is a problem with the controls of the power supply of two new bumpers installed for the MTE. Alarms are not available and the acquisition is not working yet.

PSB

Archives seem to work now but the number of users should be increased to ease the fast switching between different users, in particular for the LHC beams.

LINAC4

Discussions are ongoing on the injection HW. Two steerers were not included in the design of the injection region. Work is ongoing in the preparation of the high intensity beam for the 160 MeV/c studies. Measurements of the evolution of the emittance at 160 MeV/c are needed with shorter time intervals between measurements in order to improve the benchmark with simulations conducted by Michel Martini. Action: Michel Chanel.

Next meeting

Monday, 25^th August 2008 at 10:00 in room 354-1-001

Agenda

General Information (Gianluigi)

Status of Injection Loss Studies (Sandra)

Recent upgrades of the HEADTAIL code (Diego)

Round Table (all)

A.O.B.

Back to Minutes