Darmstadt 2008 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 18: Instrumentation und Anwendungen I

HK 18.3: Talk

Tuesday, March 11, 2008, 09:15–09:30, 2C

Acceleration of polarized electrons at the Electron Stretcher Accelerator ELSA — •Andreas Balling — Electron Stretcher Accelerator ELSA, Physikalisches Institut, Universität Bonn, Germany

Part of the hadron physics program performed at ELSA in the framework of the SFB/TR 16 is focused on double polarization experiments. In order to supply a continuous beam of polarized electrons to external experiments, several depolarizing resonances have to be overcome during beam acceleration. Therefore, at ELSA, betatron tune jumps are applied for the compensation of intrinsic resonances and harmonic closed orbit corrections for compensation of imperfection resonances.

This talk will focus on the newly developed system for the correction of vertical closed orbit distortions which consists of 30 steerer dipole magnets, increasing the available integral field strength by a factor of 3 compared to the existing setup, and 30 switching power supplies, reducing the time needed for an orbit bump application down to well below 20 milliseconds. This new system will allow for the harmonic compensation of all imperfection resonances on the fast energy ramp (even up to 5 GeV) without interfering with the interjacent intrinsic resonances. Numerical simulations of the resonance crossing, an overview of the new setup and first results will be presented.