GSI, Darmstadt
NSCL, East Lansing, Michigan
IAP, Frankfurt am Main
Funding: European Commission; contract number HPRI-CT-2001-50036 (HITRAP) German Ministry for Education and Research (BMBF; contract number 06 FY160I
Deceleration of heavy, highly charged ions from the ion storage ring ESR of the GSI accelerator facility with an rf-linear decelerator will provide ions up to bare uranium almost at rest for cutting edge experiments in atomic and nuclear physics. For this unique approach the beam has to be prepared well by electron cooling in the ESR to account for a 26 time increase of the transverse emittance during the following deceleration. An interdigital H-type (IH) structure and a radio-frequency quadrupole (RFQ) structure are operated in inverse to decelerate first from 4 MeV/u to 0.5 MeV/u and then to 6 keV/u. The quasi-continuous beam from the ESR is adapted, by using a double drift buncher, to match the longitudinal acceptance of the IH. Downstream from the IH-structure the 0.5 MeV/u beam is then fit with a spiral re-buncher to the RFQ, which finally decelerates the ions to 6 keV/u. First commissioning beam times have shown that the bunching works well and ions have been decelerated to 0.5 MeV/u in the IH structure. Extensive measurements of transversal emittance before and after deceleration can now be compared to beam dynamics calculations.
