Approach to the low temperature state oriented for crystalline beam

Noda, Akira*; Nakao, Masao*; Soda, Hikaru*; Tongu, Hiromu*; Jimbo, Koichi*; Okamoto, Hiromi*; Osaki, Kazuya*; Yuri, Yosuke; Meshkov, I.*; Smirnov, A.*; Grieser, M.*; Noda, Koji*; Shirai, Toshiyuki*; He, Z.*

Various approaches to attaining low-temperature beams have been continued in the cooler storage ring S-LSR at Kyoto University. One-dimensional ordering of electron-cooled 7-MeV protons was realized with an abrupt longitudinal temperature jump from 2 K to 0.3 K at a particle number of around 2000. Laser cooling has been applied to 40-keV Mg beams toward the realization of crystalline beams. For a coasting beam, the lowest longitudinal temperature of 3.6 K was attained at ions. The temperature was limited due to intra-beam scattering (IBS). On the other hand, the transverse temperature of the beam indirectly cooled through IBS was saturated at 500 K for ions. In order to cool the transverse direction further, synchro-betatron resonance coupling has been applied to a bunched Mg beam. The transverse temperature has been reduced to the order of K at the beam intensity of ions by the reduction of the beam intensity using a scraper.