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

Systematic measurements on transverse rms-emittance growth along the Alvarez DTL of the GSI UNILAC were performed. A high intensity argon beam was used to measure rms-growth for different transverse phase advances along the DTL. The transverse tune depression varied from 21% to 43%. For benchmarking of the experimental results four different beam dynamics codes were used: DYNAMION, PARMILA, PARTRAN, and LORASR. This paper is on the results of the experiments, the reconstruction of the initial conditions for the simulations, and on the agreement between simulations and experiments. Additionally, successful suppression of rms-growth by systematic matching is reported.

• D.-O. 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 2008 using the UNILAC at GSI. This study will serve as an excellent benchmarking.

SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.

Slides