We propose to install a storage ring at an ISOL-type radioactive beam facility for the first time. Specifically, we intend to setup the heavy-ion, low-energy ring TSR at the HIE-ISOLDE facility in...

The energy-resolved rate coefficient for the dissociative recombination (DR) of $\mathrm{H}_3{}^{+}$ with slow electrons has been measured by the storage-ring method using an ion beam produced from a radiofrequency multipole ion trap, employing buffer-gas cooling at 13 K. The electron energy spread of the merged-beams measurement is reduced to $500\mu \mathrm{eV}$ by using a cryogenic GaAs photocathode. This and a previous cold-$\mathrm{H}_3{}^{+}$ measurement jointly confirm the capability of ion storage rings, with suitable ion sources, to store and investigate $\mathrm{H}_3{}^{+}$ in the two lowest, $(J,G)=(1,1)$ and $(1,0)$ rotational states prevailing also in cold interstellar matter. The use of para-${\mathrm{H}}_2$ in the ion source, expected to enhance para-$\mathrm{H}_3{}^{+}$ in the stored ion beam, is found to increase the DR rate coefficient at meV electron energies.

Term energies for dielectronic-recombination Rydberg resonances below 0.07 eV are determined for ${\mathrm{Sc}}^{18+}$ with absolute accuracies below 0.0002 eV by electron collision spectroscopy in an ion storage ring, using the twin-electron-beam technique and a cryogenic photocathode. The lithiumlike $2s_{1/2}\mathrm{\text{−}}2p_{3/2}$ transition energy for $Z=21$ is determined to 4.6 ppm, less than 1% of the few-body effects on radiative corrections. Features from the hyperfine structure of the $2s$ state could be resolved in the dielectronic-recombination spectrum.

The hyperfine induced $2s2p{}^{3}P_0\to 2s^2{}^{1}S_0$ transition rate $A_{\mathrm{HFI}}$ in berylliumlike ${}^{47}\mathrm{Ti}^{18+}$ is measured. Resonant electron-ion recombination in a heavy-ion storage ring is employed to monitor the time dependent population of the ${}^{3}P_0$ state. The experimental value $A_{\mathrm{HFI}}=0.56(3){\mathrm{s}}^{-1}$ is almost 60% larger than theoretically predicted.