Abstract
Spectroscopic information has been extracted on the hole-states of 55Ni, the least known of the quartet of nuclei (55Ni, 57Ni, 55Co and 57Co), one neutron away from 56Ni, the N=Z=28 double magic nucleus. Using the 1H(56Ni,d)55Ni transfer reaction in inverse kinematics, neutron spectroscopic factors, spins and parities have been extracted for the f7/2, p3/2 and the s1/2 hole-states of 55Ni. This new data provides 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 reproduce the excitation energies and spectroscopic factors of the s1/2 hole state below Fermi energy.