Laser Spectroscopy of Neutron-Rich Hg,208207 Isotopes: Illuminating the Kink and Odd-Even Staggering in Charge Radii across the N =126 Shell Closure
Abstract
The mean-square charge radii of Hg,208207 (Z =80 , N =127 , 128) have been studied for the first time and those of 202,203,206Hb (N =122 , 123, 126) remeasured by the application of in-source resonance-ionization laser spectroscopy at ISOLDE (CERN). The characteristic kink in the charge radii at the N =126 neutron shell closure has been revealed, providing the first information on its behavior below the Z =82 proton shell closure. A theoretical analysis has been performed within relativistic Hartree-Bogoliubov and nonrelativistic Hartree-Fock-Bogoliubov approaches, considering both the new mercury results and existing lead data. Contrary to previous interpretations, it is demonstrated that both the kink at N =126 and the odd-even staggering (OES) in its vicinity can be described predominately at the mean-field level and that pairing does not need to play a crucial role in their origin. A new OES mechanism is suggested, related to the staggering in the occupation of the different neutron orbitals in odd- and even-A nuclei, facilitated by particle-vibration coupling for odd-A nuclei.
- Publication:
-
Physical Review Letters
- Pub Date:
- January 2021
- DOI:
- 10.1103/PhysRevLett.126.032502
- arXiv:
- arXiv:2012.13802
- Bibcode:
- 2021PhRvL.126c2502D
- Keywords:
-
- Nuclear Experiment;
- Nuclear Theory
- E-Print:
- 7 pages, 5 figures, Physical Review C, in press