• W. Barth, L.A. Dahl, P. Gerhard, L. Groening, M. Kaiser, S. Mickat
  GSI, Darmstadt

A dedicated charge separator system is now installed in the transfer line to the GSI-synchrotron SIS18. In former times charge separation was performed with a single 11 degree dipole magnet after a 25 m beam transport section. This was not adequate to meet the requirements during high current operation for FAIR: it only allows for charge state separation of low intensity and low emittance beams. With the new compact charge separator system emittance blow up and unwanted beam losses for high intensity beam operation will be avoided. Additionally a new beam diagnostics test bench is integrated. With this the beam parameters (ion current, beam profile, beam position, transversal emittance, bunch structure and beam energy) for the injection into the SIS18 can be measured in parallel to the routine operation in the transfer line. Results of the commissioning with high intensity argon beams as well as with an uranium beam will be reported.

• L. Groening, W. Barth, W.B. Bayer, G. Clemente, L.A. Dahl, P. Forck, P. Gerhard, I. Hofmann, G.A. Riehl, S. Yaramyshev
  GSI, Darmstadt
• D. Jeon
  ORNL, Oak Ridge, Tennessee
• D. Uriot
  CEA, Gif-sur-Yvette

Funding: CARE, contract number RII3-CT-2003-506395) European Community INTAS Project Ref. no. 06-1000012-8782
Transverse emittance growth along the Alvarez DTL section is a major concern with respect to the preservation of beam quality of high current beams at the GSI UNILAC. In order to define measures to reduce this growth appropriate tools to simulate the beam dynamics are indispensable. This paper is on benchmarking of three beam dynamics simulation codes, i.e. DYNAMION, PARMILA, and PARTRAN against systematic measurements of beam emittance growth for different machine settings. Experimental set-ups, data reduction, the preparation of the simulations, and the evaluation of the simulations will be described. It was found that the mean value of final horizontal and vertical rms-emittances can be reproduced well by the codes.

• D. Jeon
  ORNL, Oak Ridge, Tennessee
• G. Franchetti, L. Groening, I. Hofmann
  GSI, Darmstadt

The 4ν=1 resonance of a linac is found when the depressed tune is around 90 deg. It is observed that this fourth order resonance is dominating over the better known envelope instability and practically replacing it. Simulation study shows a clear emittance growth by this resonance and its stopband. Experimental measurement of the stopband of this resonance is proposed and conducted in early 2008 using the UNILAC at GSI. This study will serve as a excellent benchmarking.

• W. Vinzenz, W. Barth, H.-L. Dambowy, L. Groening, M. Hoerr, G. Schreiber
  GSI, Darmstadt

During the LINAC conference in Knoxville 2006 the operating frequency of the FAIR proton linac was fixed at 325.224 MHz. Even though the six CH-Structures need slightly different rf levels, the proton linac will be equipped with identical rf power sources. That applies although for the RFQ structure. To supply the FAIR accelerators with a good beam quality by the UNILAC as the high current heavy ion injector for FAIR, as well as an high duty factor accelerator for nuclear physics experiments, different upgrades and modifications have to be made at the rf components. In addition there has to be an upgrade for a planned 50% duty cycle mode, higher beam load within the post-stripper section as well as the provision of an excellent rf operation for the next 30 years. Discussions on possible collaborations with CERN in terms of LLRF and the combining of the procurement for tube amplifiers for bunching cavities are on the way. This paper describes the actual status of the proton linac rf system and the future requirements for the existing UNILAC rf systems.