The fusion excitation function of 40 Ca + 40 Ca has been measured from well above the Coulomb barrier, down to low energies where the cross section is as small as ≃20 µb, and the astrophysical S factor possibly reaches a maximum vs. energy.

The sub-barrier fusion excitation function of 40Ca + 96Zr has been measured down to cross sections ≃2.4 μb, i.e. two orders of magnitude smaller than obtained in a previous experiment, where the subbarrier fusion of this system was found to be greatly enhanced with respect to 40Ca + 90Zr, and the need of coupling to transfer channels was suggested relying on coupled-channels calculations. The purpose of this work has been to investigate the behavior of 40Ca + 96Zr fusion far below the barrier, thereby disentangling the elusive interplay of effects due to inelastic couplings, transfer couplings and, possibly, the appearance of the fusion hindrance. The smooth trend of the excitation function has been found to continue, and the logarithmic slope increases very slowly. No indication of hindrance shows up, and a comparison with 40Ca + 96 is illuminating in this respect. A new CC analysis of the complete excitation function has been performed, including explicitly one- and two-nucleon Q > 0 transfer channels. Such transfer couplings bring significant cross section enhancements, even at the level of a few μb. Locating the hindrance threshold, if any, in 40Ca + 96 would require challenging measurements of cross sections in the sub-μb range

An excitation function of one- and two-neutron transfer channels for the ^{60}Ni+^{116}Sn system has been measured with the magnetic spectrometer PRISMA in a wide energy range, from the Coulomb barrier to far below it. The experimental transfer probabilities are well reproduced, for the first time with heavy ions, in absolute values and in slope by microscopic calculations which incorporate nucleon-nucleon pairing correlations.

Background: Multinucleon transfer reactions (MNT) are a competitive tool to populate exotic neutron-rich nuclei in a wide region of nuclei, where other production methods have severe limitations or cannot be used at all. Purpose: Experimental information on the yields of MNT reactions in comparison with theoretical calculations are necessary to make predictions for the production of neutron-rich heavy nuclei. It is crucial to determine the fraction of MNT reaction products which are surviving neutron emission or fission at the high excitation energy after the nucleon exchange. Method: Multinucleon transfer reactions in 136 Xe + 238 U have been measured in a high-resolution γ -ray/particle coincidence experiment. The large solid-angle magnetic spectrometer PRISMA coupled to the high-resolution Advanced Gamma Tracking Array (AGATA) has been employed. Beamlike reaction products after multinucleon transfer in the Xe region were identified and selected with the PRISMA spectrometer. Coincident particles were tagged by multichannel plate detectors placed at the grazing angle of the targetlike recoils inside the scattering chamber. Results: Mass yields have been extracted and compared with calculations based on the GRAZING model for MNT reactions. Kinematic coincidences between the binary reaction products, i.e., beamlike and targetlike nuclei, were exploited to obtain population yields for nuclei in the actinide region and compared to x-ray yields measured by AGATA. Conclusions: No sizable yield of actinide nuclei beyond Z = 93 is found to perform nuclear structure investigations. In-beam γ -ray spectroscopy is feasible for few-neutron transfer channels in U and the −2p channel populating Th isotopes.

The fusion excitation function of 32 S + 48 Ca has been experimentally studied in a wide energy range, from above the Coulomb barrier down to cross sections in the sub-µb region. The measurements were done at INFN-Laboratori Nazionali di Legnaro, using the 32 S beam from the XTU Tandem accelerator. The excitation function has a smooth behavior below the barrier, and no evident hindrance character shows up in the measured energy region. The fusion barrier distribution has a peculiar shape with two distinct peaks of similar height, lower and higher than the Akyüz-Winther barrier. Coupled-channels calculations using the M3Y + repulsion potential are presented for this system and for 36 S+ 48 Ca. The results of these calculations give a good account of the data, and indicate the influence of one-and two-nucleon transfer channels with positive Q-values, which are only open for 32 S + 48 Ca.