Naslov
Fusion Hindrance and Pauli Blocking in 58Ni + 64Ni

Autori
Stefanini, A.M. ; Montagnoli, G. ; Fabbro, M. Del ; Colucci, G. ; Čolović, Petra ; Corradi, L. ; Fioretto, E. ; Galtarossa, F. ; Goasduff, A. ; Grebosz, J. ; Heine, M. ; Jaworski, G. ; Mazzocco, M. ; Mijatović, Tea ; Szilner, Suzana ; Bajzek, M. ; Brugnara, D. ; Siciliano, M. ; Zanon, I.

Izvornik
Journal of physics. Conference series (1742-6588) 1643 (2020); 012105, 6

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
nuclear reaction ; fusion ; sub-barrier

Sažetak
58Ni +64Ni is the first case where the influence of positive Q-value transfer channels on sub-barrier fusion was evidenced, in a very well known experiment by Beckerman et al., by comparing with the two systems 58Ni +58Ni and 64Ni +64Ni. Subsequent measurements on 64Ni +64Ni showed that fusion hindrance is clearly present in this case. On the other hand, no indication of hindrance can be observed for 58Ni +64Ni down to the measured level of 0.1 mb. In the present experiment the excitation function has been extended by two orders of magnitude downward. The cross sections for 58Ni + 64Ni continue decreasing very smoothly below the barrier, down to sime1 μb. The logarithmic slope of the excitation function increases slowly, showing a tendency to saturate at the lowest energies. No maximum of the astrophysical S-factor is observed. Coupled- channels (CC) calculations using a Woods-Saxon potential and including inelastic excitations only, underestimate the sub-barrier cross sections by a large amount. Good agreement is found by adding two-neutron transfer couplings to a schematical level. This behaviour is quite different from what already observed for 64Ni+64Ni (no positive Q-value transfer channels available), where a clear low-energy maximum of the S-factor appears, and whose excitation function is overestimated by a standard Woods-Saxon CC calculation. No hindrance effect is observed in 58Ni+64Ni in the measured energy range. This trend at deep sub-barrier energies reinforces the recent suggestion that the availability of several states following transfer with Q >0, effectively counterbalances the Pauli repulsion that, in general, is predicted to reduce tunneling probability inside the Coulomb barrier.

Izvorni jezik
Engleski

Znanstvena područja
Fizika

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