Examining the $N$ = 28 shell closure through high-precision mass measurements of ${}^{46-48}$Ar

Abstract

The strength of the $N$ = 28 magic number in neutron-rich argon isotopes is examined through high-precision mass measurements of ${}^{46-48}$Ar, performed with the ISOLTRAP mass spectrometer at ISOLDE/CERN. The new mass values are up to 90 times more precise than previous measurements. While they suggest the persistence of the $N$ = 28 shell closure for argon, we show that this conclusion has to be nuanced in light of the wealth of spectroscopic data and theoretical investigations performed with the \emph{SDPF-U} phenomenological shell model interaction. Our results are also compared with \emph{ab initio} calculations using the Valence Space In-Medium Similarity Renormalization Group and the Self-Consistent Green's Function approaches. Both calculations provide a very good account of mass systematics at and around $Z$ = 18 and, generally, a consistent description of the physics in this region. This combined analysis indicates that ${}^{46}$Ar is the transition between the closed-shell ${}^{48}$Ca and collective ${}^{44}$S.

17 pages, 14 figures

References in corpus (21)

• Nuclear magic numbers: new features far from stability
• Improved nuclear matter calculations from chiral low-momentum interactions
• Accurate nuclear radii and binding energies from a chiral interaction
• High-precision measurement of the atomic mass of the electron
• Collapse of the N=28 shell closure in ${}^{42}$Si
• Local three-nucleon interaction from chiral effective field theory
• A nucleus-dependent valence-space approach to nuclear structure
• Axially deformed solution of the Skyrme-Hartree-Fock-Bogolyubov equations using the transformed harmonic oscillator basis (II) HFBTHO v2.00d: a new version of the program
• Microscopic justification of the Equal Filling approximation
• A new effective interaction for $0\hslash \omega$ shell model calculations in the sdpf valence space
• The Ramsey method in high-precision mass spectrometry with Penning traps: Experimental results
• In-Medium Similarity Renormalization Group for Open-Shell Nuclei
• Direct mass measurements of 19B, 22C, 29F, 31Ne, 34Na and other light exotic nuclei
• Separated Oscillatory Fields for High-Precision Penning Trap Mass Spectrometry
• Probing the N = 32 shell closure below the magic proton number Z = 20: Mass measurements of the exotic isotopes 52,53K
• Measurement of excited states in 40Si and evidence for weakening of the N=28 shell gap
• Nuclear Mass Measurements Map the Structure of Atomic Nuclei and Accreting Neutron Stars
• Masses of neutron-rich ${}^{52-54}$Sc and ${}^{54,56}$Ti nuclides: The $N=32$ subshell closure in scandium
• In-beam gamma-ray spectroscopy of very neutron-rich nuclei: Excited states in 46S and 48Ar
• Quadrupole collectivity beyond N=28: Intermediate-energy Coulomb excitation of 47,48Ar
• Is the structure of 42Si understood?

Cited by in corpus (4)

• Nuclear mass predictions with machine learning reaching the accuracy required by $r$-process studies
• Mass measurements of 99-101In challenge ab initio nuclear theory of the nuclide 100Sn
• Gorkov algebraic diagrammatic construction formalism at third order
• Investigation of the ground-state spin inversion in the neutron-rich 47,49Cl isotopes