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)

Vol. 17 4 439-443

Subject Categories

Subatomic Physics

Atom and Molecular Physics and Optics

Other Physics Topics

DOI

10.1038/s41567-020-01136-5

More information

Latest update

4/28/2021