Nuclear Charge Radii ofBe7,9,10and the One-Neutron Halo NucleusBe11

Abstract

Nuclear charge radii of $^{7,9,10,11}\mathrm{Be}$ have been determined by high-precision laser spectroscopy. On-line measurements were performed with collinear laser spectroscopy in the $2{s}_{1/2}\ensuremath{\rightarrow}2{p}_{1/2}$ transition on a beam of ${\mathrm{Be}}^{+}$ 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 $^{7}\mathrm{Be}$ to $^{10}\mathrm{Be}$ and then increases for the halo nucleus $^{11}\mathrm{Be}$. When comparing our results with predictions of ab initio nuclear-structure calculations we find good agreement. Additionally, the nuclear magnetic moment of $^{7}\mathrm{Be}$ was determined to be $\ensuremath{-}1.3995(5){\ensuremath{\mu}}_{N}$ and that of $^{11}\mathrm{Be}$ was confirmed with an accuracy similar to previous $\ensuremath{\beta}$-NMR measurements.