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

Abstract

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${}_{\mathrm{sat}}$, which allows an assessment of their accuracy. We find agreement with experiment in differential radii $\delta ⟨r_{\mathrm{c}}^2⟩$ for all employed ab initio methods and interactions, while the absolute radii are consistent with data only for NNLO${}_{\mathrm{sat}}$. Within nuclear density functional theory, the Skyrme functional SV-min matches experiment more closely than the Fayans functional Fy($\Delta r$,HFB).