Extreme shape coexistence observed in 70Co

The shape of the atomic nucleus is a property that underpins our understanding of nuclear systems, impacts the limits of nuclear existence, and enables probes of physics beyond the Standard Model. Nuclei can adopt a variety of shapes, including spheres, axially deformed spheroids, and pear shapes. In some regions of the nuclear chart where a spherical nucleus would naively be expected, deformed nuclear states can result from the collective action of constituent protons and neutrons. In a small subset of nuclei both spherical and deformed nuclear states have been experimentally observed, a phenomenon termed shape coexistence. We present spectroscopic evidence for the coexistence of Jπ = 1+ spherical and deformed states in 70Co, separated by less than 275 keV. This close degeneracy of levels with the same Jπ and different shapes demonstrates an extreme example of shape coexistence resulting from the interplay of independent particle motion and collective behavior in highly unstable nuclear systems and identifies the Co isotopes as a transition point between deformed ground states observed in the Cr isotopes and spherical configurations observed in the closed-shell Ni isotopes. The atomic nucleus can adopt a variety of shapes, and instances where a single nucleus exhibits multiple shape profiles are termed shape coexistence. Here, using a combined experimental and theoretical analysis, the authors claim a rare case of shape coexistence between two states with the same spin/parity quantum numbers in the neutron-rich isotope 70Co.

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Journal
Communications Physics
Published
2025-02-23
DOI
https://doi.org/10.1038/s42005-025-01998-2
Primary Topic
Nuclear physics research studies
Type
article
Field-Weighted Citation Impact
0.00

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article

Extreme shape coexistence observed in 70Co

A. C. Larsen, A. C. Dombos, Debra Richman, Katherine Childers et al.
Communications Physics
Nuclear physics research studies
article

Extreme shape coexistence observed in 70Co

A. C. Larsen, A. C. Dombos, Debra Richman, Katherine Childers, R. Lewis, C. Dembski, B. A. Brown, R. G. T. Zegers, H. C. Berg, E. Good, N. D. Scielzo, A. Richard, Antonius Torode, D. L. Bleuel, Caley Harris, A. Spyrou, C. Sullivan, S. Lyons, A. Palmisano-Kyle, Adriana Sweet, S. N. Liddick, B. P. Crider, A. Simon, Jorge A. Pereira, Mallory K. Smith
article en

Abstract

The shape of the atomic nucleus is a property that underpins our understanding of nuclear systems, impacts the limits of nuclear existence, and enables probes of physics beyond the Standard Model. Nuclei can adopt a variety of shapes, including spheres, axially deformed spheroids, and pear shapes. In some regions of the nuclear chart where a spherical nucleus would naively be expected, deformed nuclear states can result from the collective action of constituent protons and neutrons. In a small subset of nuclei both spherical and deformed nuclear states have been experimentally observed, a phenomenon termed shape coexistence. We present spectroscopic evidence for the coexistence of Jπ = 1+ spherical and deformed states in 70Co, separated by less than 275 keV. This close degeneracy of levels with the same Jπ and different shapes demonstrates an extreme example of shape coexistence resulting from the interplay of independent particle motion and collective behavior in highly unstable nuclear systems and identifies the Co isotopes as a transition point between deformed ground states observed in the Cr isotopes and spherical configurations observed in the closed-shell Ni isotopes. The atomic nucleus can adopt a variety of shapes, and instances where a single nucleus exhibits multiple shape profiles are termed shape coexistence. Here, using a combined experimental and theoretical analysis, the authors claim a rare case of shape coexistence between two states with the same spin/parity quantum numbers in the neutron-rich isotope 70Co.

Communications PhysicsVol. 8(1)
University of Notre Dame (US), Lawrence Livermore National Laboratory (US), Pacific Northwest National Laboratory (US), University of Oslo (NO), Ohio University (US), Applied Research Laboratory at the University of Hawai‘i, University of Tennessee at Knoxville (US), The University of Texas at Austin (US), Michigan State University (US), Mississippi State University (US)
National Science Foundation
Openalex Percentile: Top 98%
Nuclear physics research studies
DOIOpen Access PDFOpenAlex
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