Charge radii of exotic potassium isotopes challenge nuclear theory and the magic character of N = 32
Journal article, 2021
Nuclear charge radii are sensitive probes of different aspects of the nucleon–nucleon interaction and the bulk properties of nuclear matter, providing a stringent test and challenge for nuclear theory. Experimental evidence suggested a new magic neutron number at N = 32 (refs. 1–3) in the calcium region, whereas the unexpectedly large increases in the charge radii4,5 open new questions about the evolution of nuclear size in neutron-rich systems. By combining the collinear resonance ionization spectroscopy method with β-decay detection, we were able to extend charge radii measurements of potassium isotopes beyond N = 32. Here we provide a charge radius measurement of 52K. It does not show a signature of magic behaviour at N = 32 in potassium. The results are interpreted with two state-of-the-art nuclear theories. The coupled cluster theory reproduces the odd–even variations in charge radii but not the notable increase beyond N = 28. This rise is well captured by Fayans nuclear density functional theory, which, however, overestimates the odd–even staggering effect in charge radii. These findings highlight our limited understanding of the nuclear size of neutron-rich systems, and expose problems that are present in some of the best current models of nuclear theory.
Author
Agota Koszorús
KU Leuven
University of Liverpool
X. F. Yang
Beijing University of Technology
KU Leuven
Weiguang Jiang
Oak Ridge National Laboratory
Chalmers, Physics, Subatomic, High Energy and Plasma Physics
University of Tennessee
S. J. Novario
Oak Ridge National Laboratory
University of Tennessee
S. W. Bai
Beijing University of Technology
J. Billowes
University of Manchester
C. L. Binnersley
University of Manchester
M. L. Bissell
University of Manchester
T. E. Cocolios
KU Leuven
B. S. Cooper
University of Manchester
R. P. de Groote
University of Jyväskylä
University of Helsinki
Andreas Ekström
Chalmers, Physics, Subatomic, High Energy and Plasma Physics
K. T. Flanagan
University of Manchester
Christian Forssén
Chalmers, Physics, Subatomic, High Energy and Plasma Physics
S. Franchoo
Institut de Physique Nucleaire Orsay
R. F.Garcia Ruiz
CERN
Massachusetts Institute of Technology (MIT)
F. P. Gustafsson
KU Leuven
G. Hagen
Oak Ridge National Laboratory
G. R. Jansen
Oak Ridge National Laboratory
A. Kanellakopoulos
KU Leuven
M. Kortelainen
University of Jyväskylä
University of Helsinki
W. Nazarewicz
Michigan State University
G. Neyens
KU Leuven
CERN
T. Papenbrock
Oak Ridge National Laboratory
University of Tennessee
P. G. Reinhard
University of Erlangen-Nuremberg (FAU)
C. M. Ricketts
University of Manchester
B. K. Sahoo
Physical Research Laboratory
A. R. Vernon
KU Leuven
University of Manchester
S. G. Wilkins
CERN
Nature Physics
1745-2473 (ISSN) 17452481 (eISSN)
Vol. 17 4 439-443Subject Categories
Subatomic Physics
Atom and Molecular Physics and Optics
Other Physics Topics
DOI
10.1038/s41567-020-01136-5