Crossing intrinsic depolarizing resonances in ELSA with pulsed betatron tune jump quadrupoles

At the electron stretcher accelerator ELSA of Bonn University an external fixed target experiment using a polarized electron beam has been started. To provide a polarized beam with sufficient intensity a dedicated source for polarized electrons is used (with a GaAs-AlGaAs superlattice photocathode). To prevent depolarization during acceleration in the circular accelerators several depolarizing resonances have to be corrected for. One type of resonances (the intrinsic ones) is compensated using two pulsed betatron tune jump quadrupoles. This method is applied because adiabatic crossing techniques that became popular in proton accelerators in the last years cannot be used in an electron accelerator due to synchrotron radiation effects at higher energies