Minutes of the LIS Section meeting held on 30 July  2012

Present: F. Antoniou, G. Arduini, H. Bartosik, M. Bodendorfer, C. Carli, V. Forte, A. Garonna, C. Hernalsteens, Y. Papaphilippou, G. Sterbini, R. Wasef.

General Information (Gianluigi)

Gianluigi welcomed Fanouria Antoniou as new member of the LIS team. She will work for 50% of her time on CLIC and for 50% of her time on the LBNO EU project for a long base line neutrino experiment.

The presentation of the LHC results on 4th July and later at the ICHEP conference has been a great success and it has [rovided and excellent image of the laboratory. More than 6 fb-1 have been collected with excellent performance in the run before the technical stop preceeding the conference.

Since the restart after the technical stop the quality of the beam has degraded and larger tails have been observed leading to larger losses during the squeeze and instabilities leading to beam losses and beam dumps. Yannis, Hannes, Simone have been heavily involved in the measurements of the beam quality in the injectors.

Given the excellent results obtained with the low gamma transition optics by Hannes and Yannis Steve Myers has requested to make this optics operational in the SPS by September so to use it for LHC physics filling.

50 ns h=9 beam will be tested in the LHC to study emittance preservation as this beam could allow to achieve sub-micrometric emittances with nominal bunch population.

Preliminary analysis on the PS wire scanners (Guido) - slides

At present it is not possible to fly more than one wire scanner in the PS on the same cycle. This is a controls issue that will be solved this week likely. Bunch-by-bunch measurement is not possible and limited mostly by cable and electronics.

Two signals are available from the wire scanner:

The Secondary emission current signal is hardly usable because of the high noise.

Yannis noted that in the SPS only a scintillator is used and because of that an asymmetry in the profiles rovided by in and out scans is observed when the beam is not centred.

Christian noted that the PSB wire scanners were using the SEM signal

The PS and PSB wire scanners are calibrated in a test bench while the SPS wire scanners aren't. It was noted that the dependence of the measured beam size on the beam position might be the result of the fact that the speed of the wire is not constant and of the absence of calibration.

Saturation might not be visible all the time, for that reason a campaign of measurements has bee done to determine the range of HV settings and filters to be used to avoid saturation for a given class of beams.

Guido is also considering the possible algorithms to characterize and quantify tails. This is of particualr importance for the LHC beams. A Levy distribution is a possible choice.

 

Next meeting

Monday, 27th August 2012 at 14:00 in room 6-R-012

Agenda:

General Information (Gianluigi)

Highlights from NuFact2012 (Simone)

Round Table (all)

 

 

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