A pr 2 01 7 Experimental probe on the production of 97 Ru from 7 Li + 93 Nb reaction : A study on the precompound emissions

Background: Interaction of weakly bound heavy-ions with an intermediate or heavy target is not yet understood completely due to the scarcity of experimental data. In order to develop a clear understanding of breakup fusion or preequilibrium emission even at low energy range, 3–10 MeV/nucleon, more experimental investigations are necessary. Purpose: Study of reaction mechanisms involved in the weakly bound heavy-ion induced reaction, Li + Nb, at low energies by measuring the production cross sections of the residual radionuclides. Method: Natural niobium (Nb) foil, backed by aluminium (Al) catcher, arranged in a stack was bombarded by Li ions of 20-45 MeV energy. Activity of the residues produced in each Nb target was measured by off-line γ-ray spectrometry after the end of bombardment (EOB) and cross sections were calculated. Experimental cross sections were compared with those computed using compound and precompound models. Results: In general, measured excitation functions of all residues produced in Li + Nb reaction showed good agreement with the model calculations based on Hauser-Feshbach formalism and exciton model for compound and precompound processes, respectively. Significant preequilibrium emission of neutrons was observed at the relatively high energy tail of the excitation function of Ru. Conclusions: Preequilibrium process played an important role for the enhancement of crosssection in xn reaction channel over the compound reaction mechanism at higher energies for Li + Nb reaction. Additionally, indirect evidence of incomplete or breakup fusion was also perceived. PACS numbers: 24.10.-i, 24.60.Dr, 25.70.-z, 25.70.Gh