Nuclear Charge Radii of Be7,9,10 and the One-Neutron Halo Nucleus Be11

Nuclear charge radii of Be7,9,10,11 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 Be7 to Be10 and then increases for the halo nucleus Be11. When comparing our results with predictions of ab initio nuclear-structure calculations we find good agreement. Additionally, the nuclear magnetic moment of Be7 was determined to be -1.3995(5)μ_N and that of Be11 was confirmed with an accuracy similar to previous β-NMR measurements.