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HK: Hadronen und Kerne
HK 25: Instrumentation III, Accelerators
HK 25.9: Talk
Tuesday, March 17, 1998, 16:15–16:30, A
Tunejump Quadrupoles for Fast Crossing of Intrinsic Resonances in ELSA — •M. Hoffmann1, D. Husmann1, S. Nakamura1, C. Steier1, and T. Toyama2 — 1Physikalisches Institut, Universität Bonn, Nußallee 12, 53115 Bonn — 2KEK, Tsukuba-305, Japan
Recently polarized electrons have been accelerated up to high energies in the 3.5 GeV Electron Stretcher Accelerator complex in Bonn. A polarization of 63% at 1.27 GeV have been achieved in an external beamline.
For energies above 2 GeV depolarizing resonances in ELSA became so strong that nearly the whole polarization was lost at the intrinsic resonance at 2.0 GeV. This type of resonance can be overcome with special tunejump quadrupoles. These are pulsed magnets which shift the vertical betatron tune of the accelerator in such a way that intrinsic resonances are crossed fast enough not to cause significant polarization loss.
Detailed design studies have been done and the magnetic field distribution has been calculated. Characteristic parameters of the magnets were measured on a prototype. The results will be presented.