Longitudinal and Transverse Coupling of the Beam Temperature Caused by the Laser Cooling of24Mg+

A laser-cooling experiment of a 40 keV 24Mg+ beam was carried out in the small laser-equipped storage ring (S-LSR). A laser co-propagating with the beam and an induction accelerator were utilized in the experiment. The lowest longitudinal temperature achieved in the present experiment was 3.6 K for 3?104 ions stored in the ring. It was found that the number of stored ions is related to the temperature at the final equilibrium state of the laser cooling. This relation shows that the longitudinal temperature of the laser-cooled beam linearly couples with the transverse one through intra-beam scattering.