LASER COOLING OF A NATURAL ISOTOPE MIXTURE OF YB+ STORED IN AN RF TRAP

We demonstrate laser cooling of Yb+, produced by ionization of a natur al isotope mixture, stored in an rf trap. One of the three major even isotopes was directly laser cooled and other isotopes were simultaneou sly trapped as a result of sympathetic cooling. It was possible to car ry out laser cooling to the temperature at which the cloud-to-crystal phase transition occurs for Yb-174(+), as observed in the case where e nriched isotopes are used. We observed sudden drops of fluorescence ow ing to pumping to the F-2(7/2) state in the case of a small number of trapped Yb+ ions.