Emerging collectivity in neutron-hole transitions near doubly magic 208Pb

M.S.M. Gerathy; A.J. Mitchell; G.J. Lane; A.E. Stuchbery; A. Akber; H.A. Alshammari; L.J. Bignell; B.J. Coombes; J.T.H. Dowie; T.J. Gray; T. Kibédi; B.P. McCormick; L.J. McKie; M.S. Rahman; M. Reece; N.J. Spinks; B.P.E. Tee; Y.Y. Zhong; K. Zhu

Physics Letters B (Dec 2021)

Emerging collectivity in neutron-hole transitions near doubly magic 208Pb

M.S.M. Gerathy,
A.J. Mitchell,
G.J. Lane,
A.E. Stuchbery,
A. Akber,
H.A. Alshammari,
L.J. Bignell,
B.J. Coombes,
J.T.H. Dowie,
T.J. Gray,
T. Kibédi,
B.P. McCormick,
L.J. McKie,
M.S. Rahman,
M. Reece,
N.J. Spinks,
B.P.E. Tee,
Y.Y. Zhong,
K. Zhu

Affiliations

M.S.M. Gerathy: Department of Nuclear Physics, Research School of Physics, The Australian National University, Canberra, ACT 2601, Australia
A.J. Mitchell: Department of Nuclear Physics, Research School of Physics, The Australian National University, Canberra, ACT 2601, Australia; Corresponding author.
G.J. Lane: Department of Nuclear Physics, Research School of Physics, The Australian National University, Canberra, ACT 2601, Australia
A.E. Stuchbery: Department of Nuclear Physics, Research School of Physics, The Australian National University, Canberra, ACT 2601, Australia
A. Akber: Department of Nuclear Physics, Research School of Physics, The Australian National University, Canberra, ACT 2601, Australia
H.A. Alshammari: Department of Nuclear Physics, Research School of Physics, The Australian National University, Canberra, ACT 2601, Australia
L.J. Bignell: Department of Nuclear Physics, Research School of Physics, The Australian National University, Canberra, ACT 2601, Australia
B.J. Coombes: Department of Nuclear Physics, Research School of Physics, The Australian National University, Canberra, ACT 2601, Australia
J.T.H. Dowie: Department of Nuclear Physics, Research School of Physics, The Australian National University, Canberra, ACT 2601, Australia
T.J. Gray: Department of Nuclear Physics, Research School of Physics, The Australian National University, Canberra, ACT 2601, Australia
T. Kibédi: Department of Nuclear Physics, Research School of Physics, The Australian National University, Canberra, ACT 2601, Australia
B.P. McCormick: Department of Nuclear Physics, Research School of Physics, The Australian National University, Canberra, ACT 2601, Australia
L.J. McKie: Department of Nuclear Physics, Research School of Physics, The Australian National University, Canberra, ACT 2601, Australia
M.S. Rahman: Department of Nuclear Physics, Research School of Physics, The Australian National University, Canberra, ACT 2601, Australia; School of Science, The University of New South Wales, Canberra, ACT 2610, Australia
M. Reece: Department of Nuclear Physics, Research School of Physics, The Australian National University, Canberra, ACT 2601, Australia
N.J. Spinks: Department of Nuclear Physics, Research School of Physics, The Australian National University, Canberra, ACT 2601, Australia
B.P.E. Tee: Department of Nuclear Physics, Research School of Physics, The Australian National University, Canberra, ACT 2601, Australia
Y.Y. Zhong: Department of Nuclear Physics, Research School of Physics, The Australian National University, Canberra, ACT 2601, Australia
K. Zhu: Department of Nuclear Physics, Research School of Physics, The Australian National University, Canberra, ACT 2601, Australia

Journal volume & issue: Vol. 823
p. 136738

Abstract

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Excited-state lifetimes were measured by direct fast-timing methods in three N=125 isotones — 209Po, 211Rn, and 213Ra — near doubly magic 208Pb. These nuclei have a single neutron hole and successively add pairs of protons relative to 208Pb. The first-excited state to ground-state transition, 5/21−→1/21−, has almost identical energy in each isotone and can be associated with the single neutron-hole transition νf5/2−1→νp1/2−1. The extent to which the protons act as spectators is assessed based on the measured transition rates, which show a systematic increase along the isotone chain, and by comparisons with large-basis shell-model calculations. The shell model accounts for some of the increased transition strength but consistently underestimates the experimental values. It also fails to explain the near-constant transition energies. These results suggest emerging collectivity beyond the shell-model valence space and show that the near-constant transition energies are not a consequence of a pure neutron-hole transition, but rather the outcome of complex nucleon-nucleon correlations that increase quadrupole collectivity.

Published in Physics Letters B

ISSN: 0370-2693 (Print); 1873-2445 (Online)
Publisher: Elsevier
Country of publisher: Netherlands
LCC subjects: Science: Physics
Website: http://www.journals.elsevier.com/physics-letters-b/

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