Systematic model calculations of the hyperfine structure in light and heavy ions (original) (raw)

2002, Canadian Journal of Physics

Systematic model calculations are performed for the magnetization distributions and the hyperfine structure (HFS) of light and heavy ions with a mass close to A ∼ 6 208 235 to test the interplay of nuclear and atomic structure. A high-precision measurement of lithium-isotope shifts (IS) for suitable transition, combined with an accurate theoretical evaluation of the mass-shift contribution in the respective transition, can be used to determine the root-mean-square (rms) nuclear-charge radius of Li isotopes, particularly of the halo nucleus Li. An experiment of this type is currently underway at GSI in Darmstadt and ISOLDE at CERN. However, the field-shift contributions between the different isotopes can be evaluated using the results obtained for the charge radii, thus casting, with knowledge of the ratio of the HFS constants to the magnetic moments, new light on the IS theory. For heavy charged ions the calculated n-body magnetization distributions reproduce the HFS of hydrogen-like ions well if QED contributions are suppressed. Ab-initio calculations of the HFS of 209 Bi 80 + were performed to analyse this surprising result. Here, the boiling of the QED vacuum gives an important contribution to the HFS, thus modifying the theoretical results of other models. The investigations performed have initiated detailed studies of the structure of lithium-like ions heavier then bismuth, to obtain predictions for the experiments on uranium, which are proposed at PHELIX-XRL. PACS Nos.: 31.15Pf, 31.30Jv, 32.10Hq, 21.10GV, 21.10FT, 21.60+n Résumé : Nous avons fait des calculs théoriques systématiques des distributions de magnétisation et HFS (structure hyperfine) dans des ions légers et lourds, autour des masses A ∼ 6 208 235 de façon à vérifier le rôle relatif des structures atomique et nucléaire. Une mesure de haute précision du déplacement isotopique (IS) de certaines transitions dans le Li peut être couplée à une évaluation théorique précise du déplacement dû à la masse dans ces transitions, afin de déterminer la racine quadratique moyenne (rms) du rayon de la charge-nucléaire des isotopes de Li, en particulier du noyau à halo 11 Li. Une expérience de ce type est en cours au GSI et à ISOLDE, CERN. Cependant, la contribution due au