Direct Evidence for the νd512 Orbital in 69Ni: Implications for the N=40 Island of Inversion
Journal article, 2025
Shape coexistence, a collective manifestation of nuclear structure, emerges from the underlying single-particle dynamics and is prominently observed in the region below 68Ni. Theoretical studies have emphasized the key role of the vd512 orbital, the quadrupole partner of vg912, in driving deformation. However, experimental constraints on the location and properties of neutron orbitals in neutron-rich isotopes in this region remain scarce. In this Letter, the single-particle structure of 69Ni was investigated via the 68Ni(d; p) reaction in inverse kinematics, performed at the ISOLDE Solenoidal Spectrometer at CERN. Several new excited states were observed, and comparisons with adiabatic distorted wave approximation (ADWA) calculations enabled l-value assignments for the most strongly populated states. In particular, a state at 2.56 MeV is interpreted as the dominant fragment of the vd512 strength. The experimental findings are well reproduced by Large-Scale Shell Model calculations using a modified LNPS interaction with an increased vg912-vd512 energy gap. These results provide new insight into the structure of 69Ni and underscore the crucial role of the vd512 orbital in the onset of collectivity at the N 1/4 40 island of inversion.
Author
A. Ceulemans
KU Leuven
R. Raabe
KU Leuven
F. Nowacki
University of Strasbourg
A. Alharbi
University of Liverpool
Qassim University
H. Ayatollahzadeh
Scottish Universities Physics Alliance
University of the West of Scotland
S. A. Bennett
University of Manchester
F. Browne
CERN
P. A. Butler
University of Liverpool
A. Camaiani
National Institute for Nuclear Physics
KU Leuven
University of Florence
D. Clarke
University of Manchester
A. J. Dolan
University of Liverpool
Z. Eleme
University of Ioannina
C. T. A. Everett
University of Liverpool
F. Flavigny
Normandie University
S. Fracassetti
KU Leuven
S. J. Freeman
CERN
University of Manchester
L. P. Gaffney
University of Liverpool
G. Georgiev
University Paris-Saclay
S. Goula
University of Ioannina
Andreas Heinz
Subatomic, High Energy and Plasma Physics
Anna Kawecka
Chalmers, Physics, Subatomic, High Energy and Plasma Physics
J. M. Keatings
Scottish Universities Physics Alliance
University of the West of Scotland
M. Labiche
UNITED KINGDOM RESEARCH AND INNOVATION (UKRI)
I. Lazarus
UNITED KINGDOM RESEARCH AND INNOVATION (UKRI)
P. T. MacGregor
CERN
University of Ioannina
University of Manchester
Maria Vittoria Managlia
Chalmers, Physics, Subatomic, High Energy and Plasma Physics
J. Ojala
University of Jyväskylä
University of Liverpool
B. Olaizola
CERN
Instituto de Nanociencia y Materiales de Aragón (INMA)
R. D. Page
University of Liverpool
N. Patronis
University of Ioannina
O. Poleshchuk
KU Leuven
A. M. Sanchez-Benitez
University of Huelva
D. K. Sharp
University of Manchester
Hans Törnqvist
Subatomic, High Energy and Plasma Physics
A. Youssef
KU Leuven
Physical Review Letters
0031-9007 (ISSN) 1079-7114 (eISSN)
Vol. 135 25 252502Creation of heavy elements in neutron-star mergers
Knut and Alice Wallenberg Foundation (2020.0076), 2021-01-01 -- 2025-12-31.
Subject Categories (SSIF 2025)
Subatomic Physics
DOI
10.1103/tdfs-5qzw