Ion Trapping Techniques: Laser Cooling and Sympathetic Cooling*

Radiation pressure from lasers has been used to cool and compress 9Be+ ions stored in a combination of static electric and magnetic fields (Penning trap) to tem eratures less than 10 mK and densities greater than lo7 cm-q in a magnetic field of 1.4 T. A technique called sympathetic cooling can be used to transfer this cooling and compression to other ion species. ions sympathetically cooled by laser cooled 9Be+ ions is given. source vi? sympathetic cooling is also discussed. A n example of lg8Hg+ The possibility of making an ultracold positron Ion traps have been used in low energy atomic physics experiments for a period of roughly 30 years.1*2) years, however, the technique of laser cooling and compression has greatly increased the potential use of stored ions in a number of applications. One example is time and frequency standards. With the technique of laser cooling and compression, ion temperatures less than 10 mK, densities a factor of 10 less than the Brillouin limit (defined below), and essentially indefinite confinement times have been obtained. 3,4) Unfortunately, elementary charged particles (electrons, positrons, protons, etc.) can not be directly laser During the past 1