Experimental study of the Ni(,)Ni one-neutron transfer reaction

Diriken, J.*; Patronis, N.*; Andreyev, A. N.; Antalic, S.*; Bildstein, V.*; Blazhev, A.*; Darby, I. G.*; De Witte, H.*; Eberth, J.*; Elseviers, J.*; Fedosseev, V. N.*; Flavigny, F.*; Fransen, Ch.*; Georgiev, G.*; Gernhuser, R.*; Hess, H.*; Huyse, M.*; Jolie, J.*; Krll, Th.*; Krcken, R.*; Lutter, R.*; Marsh, B. A.*; Mertzimekis, T.*; Mcher, D.*; Orlandi, R.  ; Pakou, A.*; Raabe, R.*; Randisi, G.*; Reiter, P.*; Roger, T.*; Seidlitz, M.*; Seliverstov, M.*; Sotty, C.*; Tornqvist, H.*; Van De Walle, J.*; Van Duppen, P.*; Voulot, D.*; Warr, N.*; Wenander, F.*; Wimmer, K.*; Muecher, D.*

Excited states up to an excitation energy of 5.8 MeV were populated in the neutron-rich isotope Ni via the Ni(d,p) transfer reaction at REX-Isolde, CERN. In particular, single-neutron states above the N=40 sub-shell gap were populated, and the relative spectroscopic factors were extracted using distorted-wave Born approximation analysis. The positive parity g, d and s neutron orbits above the shell closure are assumed to induce strong quadrupole collectivity in neutron-rich Fe and Cr isotopes. The extracted relative spectroscopic factors show that the strength of the d orbit is mostly split over two states, hinting to substantial mixing of the neutron d configuration with collective modes of the core. The size of the N=50 shell gap was also estimated, and found to be 2.6 MeV near Ni, as also determined in lighter Ni isotopes.