Challenge for more efficient transverse laser cooling for beam crystallization

ビーム結晶化のためのより効率的な横方向レーザー冷却への挑戦

野田 章*; 中尾 政夫*; 想田 光*; 頓宮 拓*; 伊藤 清一*; 岡本 宏巳*; 大崎 一哉*; 百合 庸介; 神保 光一*; Grieser, M.*; He, Z.*

Noda, Akira*; Nakao, Masao*; Soda, Hikaru*; Tongu, Hiromu*; Ito, Kiyokazu*; Okamoto, Hiromi*; Osaki, Kazuya*; Yuri, Yosuke; Jimbo, Koichi*; Grieser, M.*; He, Z.*

Mg ion beams have been successfully laser-cooled both in longitudinal and transverse directions at S-LSR in ICR, Kyoto University. The cooling rate, however, is not strong enough to realize a crystalline beam due to heating from intra-beam scattering (IBS). Reduction of the beam intensity is inevitable to suppress this IBS effect, which, however, had resulted in poor S/N ratio for observation of the transverse beam size. We, therefore, describe a new beam-scraping scheme: The scheme selects out ions in the distribution tail of the transverse phase space, keeping the beam density in the core part by simultaneous application of multi-dimensional laser cooling and beam scraping. The strategy to realize the scheme effectively has been searched by combination of the beam experiments and computer simulations.