Towards a nuclear charge radius determination for beryllium isotopes

Nuclear charge radii of 7,9,10Be and the one-neutron halo nucleus 11Be

Nuclear charge radii of ;{7,9,10,11}Be have been determined by high-precision laser spectroscopy. On-line measurements were performed with collinear laser spectroscopy in the 2s_{1/2}-->2p_{1/2} transition on a beam of Be+ ions. Collinear and anticollinear laser beams were used simultaneously, and the absolute frequency determination using a frequency comb yielded an accuracy in the isotope-shift measurements of about 1 MHz. Combining this with accurate calculations of the mass-dependent isotope shifts yields nuclear charge radii. The charge radius decreases from 7Be to 10Be and then increases for the halo nucleus 11Be. When comparing our results with predictions of ab initio nuclear-structure calculations we find good agreement. Additionally, the nuclear magnetic moment of 7Be was determined to be -1.3995(5)micro_{N} and that of 11Be was confirmed with an accuracy similar to previous beta-NMR measurements.

Frequency metrology on single trapped ions in the weak binding limit: the 3s(1/2)-3p(3/2) transition in 24Mg+

We demonstrate a method for precision spectroscopy on trapped ions in the limit of unresolved motional sidebands. By sympathetic cooling of a chain of crystallized ions, we suppress adverse temperature variations induced by the spectroscopy laser that usually lead to a distorted line profile and obtain a Voigt profile with negligible distortions. We applied the method to measure the absolute frequency of the astrophysically relevant D2 transition in single 24Mg+ ions and find 1 072 082 934.33(16) MHz, a nearly 400-fold improvement over previous results. Further, we find the excited state lifetime to be 3.84(10) ns.

High precision atomic theory for Li and Be+: QED shifts and isotope shifts

High-precision results are presented for calculations of the nonrelativistic energies, relativistic corrections, and quantum electrodynamic corrections for the 2 2S, 2 2P, and 3 2S states of Li and Be+, using nonrelativistic wave functions expressed in Hylleraas coordinates. Bethe logarithms are obtained for the states of Be+. Finite mass corrections are calculated with sufficient accuracy to extract the nuclear charge radius from measurements of the isotope shift for the 2 2S-2 2P and 2 2S-3 2S transitions. The calculated ionization potential for Be+ is 146 882.923+/-0.005 cm{-1}.