Charge radii of radium isotopes

Abstract

We present a combined analysis of the available isotope-shift data from the optical spectra of Ra atoms and Ra${}^{+}$ ions. Atomic structure calculations of the field-shift and specific mass-shift constants of the low-lying levels in Ra${}^{+}$ are used. The nuclear radial differences $\ensuremath{\delta}\ensuremath{\langle}{r}^{2}\ensuremath{\rangle}$ for the radium isotopes are derived and compared to previous analyses and nuclear models. We discuss the relevance of our results to measurements of atomic parity violation in a chain of Ra${}^{+}$ isotopes.