Laser Spectroscopy of Neutron-Rich ^{207,208}Hg Isotopes: Illuminating the Kink and Odd-Even Staggering in Charge Radii across the N=126 Shell Closure.

T Day Goodacre,P Spagnoletti,D Lunney,H Nakada,S Sels,A Zadvornaya,Y Martinez Palenzuela,S Rothe,C Van Beveren,S Kreim,F Wienholtz,M Huyse,L Schweikhard,P Ring,D Atanasov,V Manea,M Rosenbusch,L Ghys,B Andel,E Verstraelen,J Billowes,A Welker,P Van Duppen,Κ Wendt ,T E Cocolios ,R Wolf ,V N Fedosseev ,Matthieu Veinhard ,A N Andreyev ,P L Molkanov ,D V Fedorov ,L P Gaffney ,G J Farooq-Smith ,B A Marsh ,R E Rossel ,K M Lynch ,Klaus Blaum ,A E Barzakh ,M D Seliverstov ,N A Althubiti ,A V Afanasjev ,J G Cubiss ,Kieran Flanagan ,Κ Zuber

doi:10.1103/physrevlett.126.032502

Abstract

The mean-square charge radii of ^{207,208}Hg (Z=80, N=127, 128) have been studied for the first time and those of ^{202,203,206}Hg (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.

Highlights

Laser Spectroscopy of Neutron-Rich 207;208Hg Isotopes: Illuminating the Kink and Odd-Even Staggering in Charge Radii across the N = 126 Shell Closure
The majority of the discussion pertaining to the effect of shell closures on charge radii focused on the kink in the lead isotopic chain across N 1⁄4 126 [4,5,6,10,11], which is shown in the inset of Fig. 1
In this Letter, we report the first study of charge radii across N 1⁄4 126 in the mercury (Z 1⁄4 80) isotopic chain, enabling the Z dependence of the kink at N 1⁄4 126 to be probed and providing the first benchmark for theory in the region below the Z 1⁄4 82 proton shell closure

Summary

Introduction

Laser Spectroscopy of Neutron-Rich 207;208Hg Isotopes: Illuminating the Kink and Odd-Even Staggering in Charge Radii across the N = 126 Shell Closure Two near-universal features include kinks at neutron shell closures and odd-even staggering (OES), where an odd-N isotope has a smaller charge radius than the average of its two even-N neighbors [1,3].

Results

Conclusion