Multiple shape coexistence near Sn118: First 03+ lifetime measurement

Abstract

The intruder bands in Sn isotopes, built on the 2p-2h excitation across the $Z=50$ proton shell gap, are well-known examples of shape coexistence near the neutron mid-shell region. Spectroscopic signatures for shape coexistence include enhanced $E0$ transitions between the $0^{+}$ band heads. However, the underlying shape coexistence and mixing has been unclear because lifetime information for the excited $0^{+}$ states was incomplete in ${}^{118}$Sn. We thus present here the first measurement of the $0_3^{+}$ lifetime in ${}^{118}$Sn using the fast-timing technique following thermal-neutron capture. The observed enhancement in ${\rho }^2(E0;0_3^{+}\to 0_2^{+})$ of 150(30) milliunits provides compelling indications for multiple shape coexistence in ${}^{118}$Sn. Additionally, three distinct shapes in ${}^{116,118,120}$Sn naturally emerged in theoretical calculations based on the quantum-number-projected generator coordinate method employing a relativistic energy density functional.

7 pages, 2 figures, Supplemental material: https://journals.aps.org/prc/supplemental/10.1103/npjn-xpfj/Supp.pdf

References in corpus (15)

• Relativistic Continuum Hartree Bogoliubov Theory for Ground State Properties of Exotic Nuclei
• Relativistic Nuclear Energy Density Functionals: Mean-Field and Beyond
• Configuration mixing of angular-momentum projected triaxial relativistic mean-field wave functions
• Novel shape evolution in exotic Ni isotopes and configuration-dependent shell structure
• Symmetry restoration in mean-field approaches
• Three-dimensional angular momentum projection in relativistic mean-field theory
• A microscopic benchmark-study of triaxiality in low-lying states of 76Kr
• Novel shape evolution in Sn isotopes from magic numbers 50 to 82
• Systematics of low-lying states of even-even nuclei in the neutron-deficient lead region from a beyond-mean-field calculation
• Symmetry conserving configuration mixing method with cranked states
• Effective interactions and shell model studies of heavy tin isotopes
• Microscopic description of oblate-prolate shape mixing in proton-rich Se isotopes
• Occupation numbers of spherical orbits in self-consistent beyond-mean-field methods
• Ab initio nuclear shape coexistence and emergence of island of inversion around $N=20$
• Evidence for shape coexistence in ${}^{120}$Sn from the first $0_3^{+}$ lifetime measurement