Bochum 1998 – scientific programme

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HK: Hadronen und Kerne

HK 25: Instrumentation III, Accelerators

HK 25.8: Talk

Tuesday, March 17, 1998, 16:00–16:15, A

Beam-Based Measurements at ELSA — •J. Keil and D. Husmann — Physikalisches Institut, Universität Bonn, Nußallee 12, D-53115 Bonn

The Electron Stretcher Accelerator (ELSA) of Bonn University provides a nearly continuous electron beam with a high duty cycle for external experiments in the energy range between 0.5 GeV and 3.5 GeV. At the moment one of the main goals is the conservation of the polarization during acceleration and extraction. In order to avoid depolarization of the beam due to imperfection and intrinsic resonances the control of the closed orbit and the symmetry of the lattice has to be improved. The absolute position of the closed orbit in the quadrupoles is determined by changing the focusing strengths of single quadrupoles and measuring the global influence on the orbit. For calibration of the optics model of ELSA the orbit response matrix has been measured and used to fit the parameters of the accelerator lattice. Also the scaling factors for the corrector magnets and the beam position monitors were determined this way. The results of the fits of the orbit response matrix and a comparison with measurements of the optical functions of ELSA will be presented.