Minutes of the LIS Section meeting held on 2nd June 2008
Present: G. Arduini, S. Aumon, E. Benedetto, M. Chanel, A. Franchi. M. Martini, S. Maury, E. Métral, B. Mikulec, Y. Papaphilippou, G. Rumolo, B. Salvant
General Information (Gianluigi)
A staff child will arrive on 30th June to scan old paper documents. Members of the section are asked to prepare a list of documents to be scanned and send it to Lauriane with copy to Gianluigi.
The scrubbing run is being prepared. The measurements to be performed have been identified as well as the requirements in terms of beams during the phases of the scrubbing. Elias will finalize the detailed planning of the machine studies.
Training quenches in Sector 5-6 of the LHC are ongoing. It is planned to induce multiple quenches to speed up the process
TI8 extraction tests have taken place on Saturday. A small dispersion mismatch has been observed in the horizontal plane. These are the result of initial conditions which are different with respect to the theoretical ones and of a small gradient error in the focussing and defocussing quadrupoles in the FODO part of the line. The test had to be stopped on Saturday evening (initially it was planned to run until Sunday evening) due to a 18 kV cable short circuit.
Round table (all)
Elias for SPS
Elias has asked M. Gyr to have the programme for the calculation of the separatrix for the resonant slow extraction in the SPS. He has not yet received an answer.
An aperture limit has been found in LSS5 in the SPS: it was due to a bad alignment and deformation of a vacuum chamber.
It is planned to make a radiation map of the area on top of TDC2 (i.e. the switchyard for the beams for the SPS North targets) after careful tuning of the transfer line. Elias is going to organize these tests.
A problem persist with the SPS wire scanners in LSS5. The linear wire scanner in 517 is needed to measure the emittance of the beam in order to continue the transverse emittance blow-up studies.
The transverse emittance of the pilot beam was larger than nominal at PS extraction during the last TI8 test.
Bettina, Giovanni, Michel for PSB
Tests to obtain LHC beams with low bunch intensity in the PSBooster have continued. Giovanni has managed to obtain beams with bunch intensity 1 tenth of the nominal one at constant longitudinal emittance. The transverse emittance is smaller.
The preparation for the beams for MTE has started: the pencil beam has already been delivered to the PS while the large emittance beam for obtaining equal populations of the beamlets is being prepared. This year the preparation of this beam is easier because, as a result of the realignment, the working point can be moved closer to the integer without losses.
The PSB is preparing an h=1 beam for impedance measurements in contrary to what was required (h=2). After the analysis of the 2007 data it was concluded that the intensity distribution inside the bunches was not reproducible in the case of h=1. Elias and Gianluigi will discuss with Elena to understand the arguments for this change.
Sandra
The studies to understand the radiation in Goward Road are continuing. The measurements seem to indicate that the losses responsible for such radiation occur in septum 42. Optics measurements will be performed.
Andrea for MTE
The problems with the PS orbit measurement persist and do not allow the setting up of the extraction bump. The knobs for the bump adjustment are ready.
There are delays for the HW commissioning of the kickers for the MTE.
Michel Martini
There are still problems when running ORBIT with more than 7 nodes. IT is helping on that.
Yannis for PS
No support has been provided by BI for understanding the poor performance of the tune measurement spectra at large amplitude observed in 2007. Some effort should be also devoted to put in operation the BBQ.
The PS2 review took place on Thu 29/5. The R&D on a tunable 40 MHz cavity has been supported and this relaxes the constraint on the absolute value of the gamma transition for the imaginary gamma transition lattice. The possibility of considering other layouts with a larger number of straight sections has been also proposed.
Elena
she is working with F. Follin and V. Kain at the application for the emittance and Twiss parameter measurements from OTR profiles in the transfer line
PSB impedance (M. Chanel) - slides
Losses are observed in the PS Booster when the horizontal Damper is switched OFF. The losses do not occur right at injection but approximately 100 ms later (i.e. approximately at an energy of 160 MeV). If the longitudinal emittance is increased then the losses occur later. The characteristics of the horizontal instability leading to the losses have not been studied yet.
The largest contribution to the impedance comes from the extraction kickers. The impedance calculation and measurements were performed by Nassibian.
A microwave instability has been observed before the shielding of pumping manifolds. Microwave instability before the shielding of the pumping manifolds
No new measurement of the impedance of the machine has been conducted since the nineties. Michel and Giovanni plan to conduct some preliminary impedance measurements this year.
Next meeting
Monday, 16th June 2008 at 10:00 in room 354-1-001 - Please note the change of time.
Agenda
General Information (Gianluigi)
Round Table (all)
A.O.B.
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