RETRAP: An ion trap for laser spectroscopy of highly-charged ions

The possibility of highly-charged ions, captured and stored in an ion trap, and cooled by elastic collisions with confined Be ions, has been achieved in RETRAP; a cryogenic Penning trap system coupled to the Electron Beam Ion Trap (EBIT), which was used as a source of highly-charged ions. Be+ cooling in RETRAP has been carried out with a combination of resistive damping of the axial motion of the ions by a tuned circuit, and laser cooling. Spectroscopic goals of the research include metastable level lifetime measurements and precision laser spectroscopy on magnetic dipole transitions of selected highly-charged ions. Potential measurements of the hyperfine structure splitting, level lifetime, and bound state g-factor of a high-Z hydrogen-like ion 165Ho66+ already studied by emission spectroscopy in Super-EBIT, are discussed with relation to current progress.