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

The nuclear charge radii of $^{7,9,10,11}$Be have been determined by high-precision laser spectroscopy. On-line measurements were performed at ISOLDE with collinear laser spectroscopy in the $2s_{1/2} \to 2p_{1/2}$ transition of Be$^{+}$. Simultaneous measurements in collinear and anti-collinear direction combined with absolute frequency determination using a frequency comb yielded accuracy in the isotope shift measurements of better than 1 MHz. Combined with accurate calculations of the mass-dependent isotope shifts the nuclear charge radii along the isotopic chain were extracted. 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 1.3998(15) $\mu_{\rm N}$ and that of $^{11}$Be was confirmed with an accuracy similar to previous $\beta$-NMR measurements.