CONFINEMENT IN A CRYOGENIC PENNING TRAP OF HIGHEST CHARGE-STATE IONS FROM EBIT

The retrapping of highly charged Xe44+ and Th68+,72+ ions extracted fr om an ''electron-beam ion trap'' (EBIT) is demonstrated after injectio n of the ions into RETRAP, a cryogenic Penning trap (up to 6 T magneti c field) currently with an open cylinder design. Ion extraction in a s hort pulse (5-20 mus) from EBIT, essential for efficient retrapping, i s employed. The ions are slowed down upon entering a deceleration tube mounted above the trap within the magnetic field. The potential is th en rapidly (100 ns) decreased, enabling low-energy ions to enter the t rap. Capture efficiencies up to 25% are observed via detection of the delayed ion release pulse with a detector below the trap. Signal volta ges induced in a tuned circuit due to single and multiple ions have be en observed by tuning the ion resonant axial oscillation frequencies f or different ions. Results from transporting and retrapping of the ion s, as well as their detection, are described and the trapping efficien cy is discussed. The motivation for these studies is to cool the trapp ed very highly charged ions to low temperatures (<4 K) in order to per form ultrahigh-resolution precision spectroscopy, collision studies at ultralow energies, and to observe phase transitions in Coulomb cluste rs of highly charged ions.