Isospin Symmetry Breaking Disclosed in the Decay of Three-Proton Emitter 20Al
Journal article, 2025
The previously unknown nucleus 20Al has been observed for the first time by detecting its in-flight decays. Tracking trajectories of all decay products with silicon microstrip detectors allowed for a conclusion that 20Al is unbound with respect to three-proton (3p) emission. The 3p-decay energy of the 20Al ground state has been determined to be 1.93(+0.12-0.10) MeV through a detailed study of angular correlations of its decay products, 17Ne + p + p + p. This value is significantly smaller than the predictions inferred from the isospin symmetry by using the known neutron separation energy of its mirror nucleus 20N, which indicates a possible isospin symmetry breaking in the mirror nuclei 20Al and 20N. This observed isospin symmetry breaking is supported by the calculations of the continuum embedded theoretical frameworks, describing the observed 20Al ground state as a 1p s-wave state with a spin-parity of 1-, which differs from the spin-parity (2-) of the 20N ground state. The 20Al ground state decays by sequential 1p-2p emission via the intermediate ground state of 19Mg, which is the first observed case of "daughter" 2p radioactivity following 1p decay of the parent state.
Author
X. -D. Xu
Chinese Academy of Sciences
I. Mukha
Helmholtz Association of German Research Centres
J. G. Li
Chinese Academy of Sciences
S. M. Wang
Fudan University
National Natural Science Foundation of China (NSFC)
L. Acosta
Universidad Nacional Autónoma de México
Instituto de Nanociencia y Materiales de Aragón (INMA)
M. Bajzek
University of Zagreb
Justus Liebig University Giessen
Helmholtz Association of German Research Centres
E. Casarejos
University of Vigo
D. Cortina-Gil
Universitat de Valencia
J. M. Espino
University of Seville
A. Fomichev
Flerov Laboratory of Nuclear Reactions (FLNR)
H. Geissel
Helmholtz Association of German Research Centres
J. Gomez-Camacho
University of Seville
L. V. Grigorenko
National Research Nuclear University (MEPhI)
Kurchatov Institute
Flerov Laboratory of Nuclear Reactions (FLNR)
O. Kiselev
Helmholtz Association of German Research Centres
A. A. Korsheninnikov
Kurchatov Institute
D. Kostyleva
Helmholtz Association of German Research Centres
N. Kurz
Helmholtz Association of German Research Centres
Yu. A. Litvinov
Helmholtz Association of German Research Centres
I. Martel
University of Huelva
C. Nociforo
Helmholtz Association of German Research Centres
M. Pfuetzner
University of Warsaw
Helmholtz Association of German Research Centres
C. Rodriguez-Tajes
Universidade de Santiagode Compostela
C. Scheidenberger
Helmholtz Association of German Research Centres
Justus Liebig University Giessen
K. Suemmerer
Helmholtz Association of German Research Centres
H. Weick
Helmholtz Association of German Research Centres
Justus Liebig University Giessen
P. J. Woods
University of Edinburgh
Mikhail Zhukov
Chalmers, Physics
Physical Review Letters
0031-9007 (ISSN) 1079-7114 (eISSN)
Vol. 135 2 022502Roots
Basic sciences
Subject Categories (SSIF 2025)
Subatomic Physics
DOI
10.1103/hkmy-yfdk
PubMed
40743202