Preequilibrium GDR excitation and entrance channel angular momentum effects

The energy spectra of the γ-rays emitted in the 35Cl + 92Mo reaction at incident energy E = 260 MeV were measured in coincidence with the ejectiles produced in dissipative reaction events. The cumulative energy spectrum of the γ-rays coming from the decay of the ejectiles was calculated within the statistical model and its comparison to the experimental spectrum evidences an excess in the data for Eγ = 8 to 12 MeV. Such an excess, fitted with a Lorentz curve, is attributed to the preequilibrium GDR γ-decay of the intermediate dinuclear system. The centroid energy of the Lorentz curve corresponds to a dipole oscillation along the symmetry axis of the system and its width is found to be comparable to that of the ground state GDR low energy component of the deformed dinucleus. The small quantal dispersion Δl = (10.3 ± 0.1)ħ of the entrance channel angular momentum, determined by analysing the dissipative fragment angular distribution in the framework of the Strutinsky model, is suggested to limit the broadening of the preequilibrium GDR width

Does the breakup process affect the reaction dynamics for the systems 17O, 17F + 58Ni at Coulomb barrier energies?

The scattering processes of two mirror projectiles, the well bound 17O (Sn = 4.143 MeV) and the loosely bound radioactive 17F (Sp = 0.600 MeV), on the proton closed shell target 58Ni were measured at several energies around the Coulomb barrier. The experimental data were analyzed within the framework of the optical model to extract the reaction cross section and to investigate the role played by direct reaction channels at near-barrier energies. The comparison shows a similar behaviour for the two A = 17 projectiles despite their very different binding energies and suggests a rather small effect of the 17F breakup channel on the reaction dynamics