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Brinker, F.

Paper Title Page
MOPLT044 Longitudinal Positron Polarisation in HERA-II 644
 
  • E. Gianfelice-Wendt, D.P. Barber, F. Brinker, W. Decking, J. Keil, M. Vogt, F.J. Willeke
    DESY, Hamburg
  
  Following the installation of two more pairs of spin rotators in the course of the HERA Luminosity Upgrade, longitudinal positron spin polarisation has now been generated simultaneously at all three positron(electron) interaction points in HERA at the routine energy of 27.5 GeV. The maximum attained so far is 54 percent. The theoretical maximum for this configuration and in the presence of realistic errors is 57.0 percent. This is the first time in the history of high energy electron storage ring physics that the naturally occurring vertical polarisation has been, with the aid of spin rotators, converted to longitudinal polarisation at three interaction points simultaneously. We describe the measures needed to attain polarisation in light of the HERA Upgrade and the resulting recent performance.  
TUPLT035 Online Calculation of the Beam Trajectory in the HERA Interaction Regions 1222
 
  • F. Brinker
    DESY, Hamburg
  
  During the HERA luminosity upgrade the new super conducting mini beta quadrupoles have been placed inside the experiments for final focussing and separation of the lepton and proton beams. The synchrotron radiation of up to 12 kW produced in these magnets passes through the detector and is absorbed behind the experiments. In order to avoid background events from synchrotron radiation it is a mandatory to adjust precisely the beam trajectory before and inside the detector. A procedure has been developed to calculate the trajectory in the interaction regions. With a beam-based alignment the offsets of the beam with respect to the quadrupoles is measured. From this measurement the offsets of the quadrupoles and of the beam position monitors are fitted. With the knowledge of these offsets the trajectory of the beam is calculated with high precision. The display of the trajectory is online available as an operational tool for beam steering and background optimization.  
THPKF020 Improvements of the Orbit Stability at DORIS III 2302
 
  • F. Brinker, O. Kaul
    DESY, Hamburg
  
  Running since 1974, the storage ring DORIS experienced a major modification in 1991 to run as a dedicated synchrotron radiation source since 1993. Since then the increasing requirements of the users on beam stability lead to a series of technical and operational measures to improve the beam conditions. The beam pipe has been mechanically isolated from the magnets, the cooling has been improved and this year a new orbit feedback came to operation which uses positron beam position monitors as well as photon monitors in the beam lines to stabilise the different photon beams. The different measures taken are presented.  
THPLT042 Automated Orbit Control for the HERA ep Collider 2571
 
  • S.W. Herb, P.K. Bartkiewicz, F. Brinker, J.M. Maass
    DESY, Hamburg
  
  Successful operation of the HERA electron-proton collider requires maintaining stable orbits during the typically 12 hour luminosity runs, as well as during the fill and acceleration procedures. The primary sources of orbit errors for the electron ring are the interaction region magnets, whose support structures are integrated with the experimental detectors and susceptible to thermal and magnetic effects. The orbit correction algorithms are designed to correct these effects locally, while operating with somewhat reduced sensitivity on error sources in the rest of the ring. We describe the correction system and our operating experience.  
THPLT043 Development of a New Orbit Measurement System 2574
 
  • O. Kaul, F. Brinker, R. Neumann, R. Stadtmüller
    DESY, Hamburg
  
  Since DORIS III became a dedicated source for synchrotron radiation in 1993, the demands of the synchrotron-light-users concerning the beam position stability have permanently increased.In order to improve this stability, different measures have been adopted, all with success. The vacuum chambers have been renewed, since they were the source of quadrupole movement, which caused strong horizontal orbit distortion. In 2003 a new orbit position control was implemented, based on the ?Singular Value Decomposition? method. The position information comes from synchrotron light monitors, installed in the beam-lines, and from the orbit measurement system, which operates with a maximal measurement rate of 5Hz and a spatial resolution not less than 20μm. To satisfy the requirements for beam-position stability, the orbit measurement system has been further developed. The test stage is nearly finished and the new system will be installed soon. The orbit measurement rate will exceed 250Hz und the spatial resolution will be less than 2μm. In addition beam oscillations of up to 20Hz can be damped.