Neutron spectroscopic factors of 55 Ni hole-states from (p, d) transfer reactions

Abstract Spectroscopic information has been extracted on the hole-states of 55Ni, the least known of the quartet of nuclei (55Ni, 57Ni, 55Co and 57Cu), one nucleon away from 56Ni, the N = Z = 28 double magic nucleus. Using the H 1 ( Ni 56 , d ) Ni 55 transfer reaction in inverse kinematics, neutron spectroscopic factors, spins and parities have been extracted for the f 7 / 2 , p 3 / 2 and the s 1 / 2 hole-states of 55Ni. These new data provide a benchmark for large basis calculations that include nucleonic orbits in both the sd and pf shells. State of the art calculations have been performed to describe the excitation energies and spectroscopic factors of the s 1 / 2 hole-state below Fermi energy.