GSI, Darmstadt
The GSI linear accelerator UNILAC and the synchrotron SIS18 will feed the future accelerator facility FAIR (Facility for Antiproton and Ion Research) with heavy ion beams. Several hardware measures at the UNILAC are necessary to meet the FAIR requirement, implicating a beam intensity of 3.2·1011 of U28+-particles within an UNILAC macro pulse of 100μs length and defined emittance space at SIS18 injection. The stripper gas jet density was strongly increased to get the equilibrium charge state even for the heaviest ions. A procedure matching the 6-D-phase space for proper A lvarez DTL injection and increase of the transverse phase advance in the Alvarez accelerators reduces emittance growth. In front of SIS18 injection a new separator provides an immediate selection of the desired charge state after stripping and therefore reduces space charge induced emittance growth. The front-end of the high current injector includes several bottle necks. A compact solenoid channel is planned providing straight line injection into the 4-rod- RFQ. The RFQ will be equipped with new designed electrodes for increased acceptance and reduced emittance growth. The contribution gives an overview of end-to-end simulations, the different upgrade measures, the particular beam investigations, and the status of beam development satisfying FAIR requirements.
MSU/NSCL, East Lansing
GSI, Darmstadt
Goethe Universität Frankfurt/IAP, Frankfurt
Funding: Work supported by the BMBF.
The GSI accelerator facility provides highly charged ion beams up to U92+ at the energy of 400 MeV/u. These are cooled and decelerated down to 4 MeV/u in the Experimental Storage Ring. Within the Heavy Ion Trap facility HITRAP the ions are decelerated further down. The linear decelerator comprises a 108/216 MHz doubledrift- buncher, a 108 MHz-IH-structure, a spiral-type rebuncher, and an RFQ-decelerator with an integrated debuncher providing energy spread reduction. Finally the beam is injected with the energy of 6 keV/u into a Penning trap for final cooling. The decelerator is installed completely and first sections have been successfully commissioned. For commissioning of the individual sections different ion species, e.g. 64Ni28+, 20Ne10+, 197Au79+ were used. Each section was studied with comprehensive beam diagnostics to measure energy, emittance, intensity, transverse profiles, and bunch structure of the beam. The report gives an overview of the beam dynamics, the decelerator structures, and some results of the different commissioning runs.