Nuclear Charge Radii of Be-7,9,10 and the one-neutron halo nucleus Be-11

Abstract

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 \(2s_{1/2} \to 2p_{1/2}\) 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. Combination with accurate calculations of the mass-dependent isotope shifts yield nuclear charge radii. The charge radius decreases from \(^7\)Be to \(^{10}\)Be and then increases for the halo nucleus \(^{11}\)Be. When comparing our results with predictions of {\it ab initio} nuclear structure calculations we find good agreement. Additionally, the nuclear magnetic moment of \(^7\)Be was determined to be \(-1.3995(5)\mu_{\rm N}\) and that of \(^{11}\)Be from a previous \(\beta\)-NMR measurement was confirmed.