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

doi:10.1103/PhysRevLett.126.032502

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

Phys Rev Lett. 2021 Jan 22;126(3):032502. doi: 10.1103/PhysRevLett.126.032502.

Authors

T Day Goodacre^{1

2

3}, A V Afanasjev⁴, A E Barzakh⁵, B A Marsh², S Sels^{2

6}, P Ring⁷, H Nakada⁸, A N Andreyev^{9

10}, P Van Duppen⁶, N A Althubiti^{1

11}, B Andel^{6

12}, D Atanasov¹³, J Billowes¹, K Blaum¹³, T E Cocolios^{1

6}, J G Cubiss⁹, G J Farooq-Smith^{1

6}, D V Fedorov⁵, V N Fedosseev², K T Flanagan^{1

14}, L P Gaffney^{6

15}, L Ghys^{6

16}, M Huyse⁶, S Kreim^{2

13}, D Lunney¹⁷, K M Lynch^{1

2}, V Manea¹³, Y Martinez Palenzuela^{2

6}, P L Molkanov⁵, M Rosenbusch¹⁸, R E Rossel^{2

19}, S Rothe², L Schweikhard¹⁸, M D Seliverstov⁵, P Spagnoletti¹⁵, C Van Beveren⁶, M Veinhard², E Verstraelen⁶, A Welker^{2

20}, K Wendt¹⁹, F Wienholtz^{2

18}, R N Wolf^{13

18}, A Zadvornaya⁶, K Zuber²⁰

Affiliations

¹ The University of Manchester, School of Physics and Astronomy, Oxford Road, Manchester M13 9PL, United Kingdom.
² CERN, CH-1211 Geneva 23, Switzerland.
³ TRIUMF, Vancouver V6T 2A3, Canada.
⁴ Department of Physics and Astronomy, Mississippi State University, Mississippi 39762, USA.
⁵ Petersburg Nuclear Physics Institute, NRC Kurchatov Institute, Gatchina 188300, Russia.
⁶ KU Leuven, Instituut voor Kern- en Stralingsfysica, B-3001 Leuven, Belgium.
⁷ Fakultät für Physik, Technische Universität München, D-85748 Garching, Germany.
⁸ Department of Physics, Graduate School of Science, Chiba University, Yayoi-cho, I-33, Inage, Chiba 263-8522, Japan.
⁹ Department of Physics, University of York, York YO10 5DD, United Kingdom.
¹⁰ Advanced Science Research Center (ASRC), Japan Atomic Energy Agency (JAEA), Tokai-mura, Japan.
¹¹ Physics Department, Faculty of Science, Jouf University, Aljouf P.O. Box 2014, Saudi Arabia.
¹² Department of Nuclear Physics and Biophysics, Comenius University in Bratislava, 84248 Bratislava, Slovakia.
¹³ Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany.
¹⁴ The Photon Science Institute, The University of Manchester, Manchester M13 9PL, United Kingdom.
¹⁵ School of Computing, Engineering, and Physical Sciences, University of the West of Scotland, Paisley PA1 2BE, United Kingdom.
¹⁶ Belgian Nuclear Research Center SCK CEN, Boeretang 200, B-2400 Mol, Belgium.
¹⁷ CSNSM-IN2P3, Université de Paris Sud, 91405 Orsay, France.
¹⁸ Universität Greifswald, Institut für Physik, 17487 Greifswald, Germany.
¹⁹ Institut für Physik, Johannes Gutenberg-Universität, D-55099 Mainz, Germany.
²⁰ Institut für Kern- und Teilchenphysik, Technische Universität Dresden, Dresden 01069, Germany.

PMID: 33543945
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.