First Measurement of Collectivity of Coexisting Shapes Based on Type II Shell Evolution: The Case of ^{96}Zr

Phys Rev Lett. 2016 Oct 21;117(17):172503. doi: 10.1103/PhysRevLett.117.172503. Epub 2016 Oct 17.

Abstract

Background: Type II shell evolution has recently been identified as a microscopic cause for nuclear shape coexistence.

Purpose: Establish a low-lying rotational band in ^{96}Zr.

Methods: High-resolution inelastic electron scattering and a relative analysis of transition strengths are used.

Results: The B(E2;0_{1}^{+}→2_{2}^{+}) value is measured and electromagnetic decay strengths of the 2_{2}^{+} state are deduced.

Conclusions: Shape coexistence is established for ^{96}Zr. Type II shell evolution provides a systematic and quantitative mechanism to understand deformation at low excitation energies.