Speaker
Description
The neutron-rich nuclei below the nickel isotopic chain manifest a sudden onset of collectivity going toward $N=40$, despite the proximity of the magic $Z=28$ number. This is interpreted as a result of the change in the underlying shell structure allowing correlation energies to dominate the monopole energy. In other words, structures built on Np-Nh configurations become yrast: we are in the Island of Inversion (IoI). The configurations that are yrast in the IoI can often be found as non-yrast structures in neighboring nuclei and give rise to shape-coexistence. Therefore, further nuclear structure studies devoted to the exploration of shape-coexistence phenomena in nuclei near to the IoI at $N=40$ will provide valuable data to constrain and test nuclear theory.
To study the presence of coexisting shapes, the measurement of experimental accessible nuclear properties, such as the lifetime of the $0_j^+$ excited states, is essential. We propose to measure the lifetime of the first excited $0_j^+$ states in $^{60}$Fe with the Recoil Distance Doppler Shift technique by populating low-lying yrast and non-yrast states in $^{60}$Fe via the multi-nucleon transfer reaction $^{58}$Fe($^{18}$O,$^{16}$O)$^{60}$Fe at energy below the Coulomb barrier. De-excitation $\gamma$ rays will be detected in coincidence with the back-scattered ions of $^{16}$O by using the $\gamma$-rays tracking array AGATA and the SPIDER detector for heavy ions.
