# Evidence for coexisting shapes in $^{98}$Zr through lifetime measurements

## TL;DR

This study measures lifetimes of excited states in $^{98}$Zr, revealing coexistence of multiple shapes and confirming a sudden increase in collectivity at neutron number 60 through experimental and theoretical analysis.

## Contribution

It provides new lifetime measurements in $^{98}$Zr and demonstrates the coexistence of multiple nuclear shapes using experimental data and advanced theoretical models.

## Key findings

- Small B(E2) value confirms sudden onset of collectivity.
- Evidence of shape coexistence in $^{98}$Zr.
- Comparison with theoretical models supports experimental conclusions.

## Abstract

The lifetimes of first excited 2$^+$, 4$^+$ and 6$^+$ states in $^{98}$Zr were measured with the Recoil-Distance Doppler Shift method in an experiment performed at GANIL. Excited states in $^{98}$Zr were populated using the fission reaction between a 6.2 MeV/u $^{238}$U beam and a $^{9}$Be target. The $\gamma$ rays were detected with the EXOGAM array in correlation with the fission fragments identified in mass and atomic number in the VAMOS++ spectrometer. Our result shows very small B(E2;2$_1^+$ $\rightarrow$ 0$_1^+$) value in $^{98}$Zr thereby confirming the very sudden onset of collectivity at $N=60$. The experimental results are compared to large-scale Monte Carlo Shell model and beyond mean field calculations. The present results indicate coexistence of two additional deformed shapes in this nucleus along with the spherical ground state.