Nuclear Charge Radii of the Nickel Isotopes \(^{58-68,70}\)Ni

Collinear laser spectroscopy is performed on the nickel isotopes \(^{58-68,70}\)Ni, using a time-resolved photon counting system. From the measured isotope shifts, nuclear charge radii \(R_c\) are extracted and compared to theoretical results. Three ab initio approaches all employ, among others, the chiral interaction NNLO\(_{\rm sat}\), which allows an assessment of their accuracy. We find agreement with experiment in differential radii \(\delta \left\langle r_\mathrm{c}^2 \right\rangle\) for all employed ab initio methods and interactions, while the absolute radii are consistent with data only for NNLO\(_{\rm sat}\). Within nuclear density functional theory, the Skyrme functional SV-min matches experiment more closely than the Fayans functional Fy(\(\Delta r\),HFB).