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Gras, J.J.

Paper Title Page
CT08 Adaptive Optics for the LEP 2 Synchrotron Light Monitors 77
 
  • G. Burtin, R.J. Colchester, G. Ferioli, J.J. Gras, R. Jung, J.M. Vouillot
    CERN, Geneva, Switzerland
 
  The image obtained with the LEP synchrotron radiation telescopes deteriorates, giving multiple and deformed images, when the beam energy goes beyond 80 GeV at beam currents above 2 mA. This problem is due to the deformation of the light extracting beryllium mirror, by as little as 1 mm, and had been predicted at the design stage. To overcome this problem, several changes together with an adaptive optics set-up have been introduced. These essentially consist of a cylindrically deformable mirror to compensate the cylindrical deformation of the beryllium mirror and a movable detector to compensate the spherical deformation. Both components are continuously adjusted as a function of beam current and energy.  
CT11 The OTR Screen Betatron Matching Monitor of the CERN SPS 90
 
  • C. Bovet, R.J. Colchester, G. Ferioli, J.J. Gras, R. Jung, J.M. Vouillot
    CERN, Geneva, Switzerland
 
  In order to satisfy the stringent emittance requirements of LHC, betatron matching monitors, based on multiturn beam profile measurements, have been proposed for the SPS and LHC. A test monitor has been installed for evaluation in the CERN SPS first in 1996 and improved in 1997. It is based on an OTR screen and a fast beam profile acquisition system. It has been used with proton beams to assess the quality of the betatron matching from the PS to the SPS in 1998. Experience and results are presented.  
PS15 Beam profile measurements at 40 MHz in the PS to SPS transfer channel 135
 
  • G. Ferioli, J.J. Gras, H. Hiller, R. Jung
    CERN, Geneva, Switzerland
 
  Bunch to bunch beam profile measurements provide a valuable tool to control the injection lines to the SPS. A fast profile monitor based on a 2.5μm Mylar coated with Aluminium Optical Transition Radiation (OTR) radiator, has been developed, installed and tested in the transfer line between the PS and SPS. The OTR beam image is focused onto a fast Linear Multianode Photo Multiplier Tube and the associated electronics sample and store profiles every 25ns. The paper describes the detector design, the electronic processing, and presents the results of different measurements made with bunches of 109-1011 protons at 26 GeV, and bunches of 106 Pb82+ ions at 5.11 GeV/u.