• A. Noda, M. Nakao, H. Souda, H. Tongu
  Kyoto ICR, Uji, Kyoto
• M. Grieser
  MPI-K, Heidelberg
• K. Jimbo
  Kyoto IAE, Kyoto
• I.N. Meshkov, A.V. Smirnov
  JINR, Dubna, Moscow Region
• K. Noda, T. Shirai
  NIRS, Chiba-shi
• H. Okamoto
  HU/AdSM, Higashi-Hiroshima
• S. Shibuya
  AEC, Chiba

Funding: The present work was supported by Advanced Compact Accelerator Development program by MEXT of Japanese Government. Support from Global COE, The Next Generation of Physics, is also greatly appreciated.

Creation of 3-dimensional crystalline beam by application of laser-cooling for a Mg ion beam with kinetic energy of 40 keV is a major research subject of the ion storage ring, S-LSR, at ICR, Kyoto University*. Based on the success of longitudinal laser cooling in 2007**, an approach to extend the effect of laser cooling to the transverse degree of freedom has been performed. An indication of heat transfer from the horizontal to longitudinal direction has been obtained by synchro-betatron coupling. By application of bunched beam laser cooling at the operation point around (2.07, 1.10), the momentum spread of the cooled ion beam has been observed to have a peak at a synchrotron tune around 0.07 and simultaneously transverse beam size seems to be reduced in this region. An increase of beam brightness in the horizontal profile has also been observed by measuring spontaneous emission of absorbed laser light. In the present paper, strategy to reach the final 3-dimensional crystalline state by application of 3-dimensional laser cooling by careful adjustment of coupling among 3 degrees of freedom is to be presented based upon the recent experimental results.

*A. Noda, M. Ikegami, T. Shirai, New Journal of Physics, 8, 288-307(2006).
**M. Tanabe et al.,Applied Physics Express 1, 028001-1-028001-3 (2008).