Inverse odd-even staggering in nuclear charge radii and possible octupole collectivity in 217,218,219At revealed by in-source laser spectroscopy

© 2019 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Hyperfine-structure parameters and isotope shifts for the 795-nm atomic transitions in At217,218,219 have been measured at CERN-ISOLDE, using the in-source resonance-ionization spectroscopy technique. Magnetic dipole and electric quadrupole moments, and changes in the nuclear mean-square charge radii, have been deduced. A large inverse odd-even staggering in radii, which may be associated with the presence of octupole collectivity, has been observed. Namely, the radius of the odd-odd isotope At218 has been found to be larger than the average of its even-N neighbors, At217,219. The discrepancy between the additivity-rule prediction and experimental data for the magnetic moment of At218 also supports the possible presence of octupole collectivity in the considered nuclei.status: publishe