Fusion of ⁶⁰Ni + ¹⁰⁰Mo near and below the Coulomb barrier

A. M. Stefanini, Laboratori Nazionali di Legnaro
G. Montagnoli, Università degli Studi di Padova
F. Scarlassara, Università degli Studi di Padova
C. L. Jiang, Argonne National Laboratory
H. Esbensen, Argonne National Laboratory
E. Fioretto, Laboratori Nazionali di Legnaro
L. Corradi, Laboratori Nazionali di Legnaro
B. B. Back, Argonne National Laboratory
C. M. Deibel, Argonne National Laboratory
B. Di Giovine, Argonne National Laboratory
J. P. Greene, Argonne National Laboratory
H. D. Henderson, Argonne National Laboratory
S. T. Marley, Argonne National Laboratory
M. Notani, University of Notre Dame
N. Patel, Argonne National Laboratory
K. E. Rehm, Argonne National Laboratory
D. Sewerinyak, Argonne National Laboratory
X. D. Tang, University of Notre Dame
C. Ugalde, Argonne National Laboratory
S. Zhu, Argonne National Laboratory

Abstract

The fusion excitation function of 60Ni + 100Mo has been measured from above the Coulomb barrier down to a cross section around 2 μb, looking for coupling and hindrance effects in this soft medium-mass system with positive Q-values for several neutron transfer channels. A comparison is made with previous results for 64Ni + 100Mo where no Q > 0 transfer channels exist and the hindrance effect is quite clear. The two excitation functions are very similar, as well as the corresponding logarithmic derivatives showing analogous saturations below the barrier. It appears that transfer couplings to Q > 0 channels seem to play a marginal role near and below the barrier for 60Ni + 100Mo, even if measurements of cross sections lower than 1 μb would be needed also for this system. Coupled-channels calculations confirm these observations and indicate that multi-phonon excitations dominate the fusion dynamics in the whole measured energy range. © Società Italiana di Fisica/Springer-Verlag 2013.