Laser spectroscopy of highly charged ions at the storage ring CSRe: Schottky-based spectroscopic investigation and XUV fluorescence detector development

Laser spectroscopy stands out as a powerful tool to investigate atomic and nuclear properties and also test fundamental theories by precisely measuring the energy levels in highly charged ions. In this work, the finestructure splitting 1s 2 2s 2 S 1/2 - 1s 2 2p 2 P 1/2 transition in lithium -like 16 O 5+ has been investigated in a laser spectroscopy experiment at the heavy -ion storage ring CSRe. The excitation resonance of the tunable narrowband UV laser and the ions was observed using a Schottky resonator with very high sensitivity. The experimental uncertainties including the ion beam velocity determination, the space charge effects, laser wavelength calibration, and angular misalignment between the laser and ion beam were analyzed, and the 2 S 1/2 - 2 P 1/2 transition wavelength was determined to be lambda 0 = 103.45(38) nm. The primary source of experimental uncertainty arises from the inaccurate measurement of the high voltage applied on the electron cooler and therewith the ion beam velocity at the CSRe. In order to solve this problem, a high -precision divider to precisely measure the highvoltage of the electron cooler is under construction, which is expected to improve the present experimental accuracy by three orders of magnitude. In addition, an XUV optical detector equipped with an off -axis parabolic mirror has been developed and installed at the CSRe for the investigation of slow dipole -forbidden transitions in highly charged ions, such as hyperfine splitting and M1 transitions. The experimental studies presented here pave the way for future laser spectroscopy experiments at the CSRe as well as at the future larger -scale scientific facility HIAF in China.