Microscopic structure of coexisting 0 states in Ni probed via two-neutron transfer

Flavigny, F.*; Elseviers, J.*; Andreyev, A. N.; Bauer, C.*; Bildstein, V.*; Blazhev, A.*; 31 of others*

The Ni isotope is known for exhibiting signs of shape coexistence at very low excitation energies. In this work, carried out at REX-Isolde, CERN, the Ni(,) reaction in inverse kinematics was studied for the first time and used to assess directly the active neutrons orbitals responsible its shape coexistence. The main states populated were the ground state, the second state at 1604~keV, and the first excited 2 state at 2033 keV. The analysis of the differential transfer cross-sections and comparison with theoretical DWBA calculations permitted to quantify the contribution of neutron orbits below the =40 gap in the structure of these states. This information is essential to better understand the phenomenon of shape coexistence in the region of medium-heavy nuclei.