Experimental study of incomplete fusion reactions in the O 16 + Te 130 system below 6 MeV/nucleon

Abstract

Background: The measurement and analysis of excitation functions may be used as an important tool to understand incomplete fusion reaction dynamics. Purpose: Several studies have been carried out to study incomplete fusion reactions at low energies, but a clear picture of incomplete fusion reaction processes at energies below 6 MeV/nucleon has yet to emerge. Further, there is no theoretical model which may give a good representation of incomplete fusion processes. Method: Off-line γ-ray spectrometry has been used to measure the excitation functions in the 16O+130Te system at energies ≈3-6 MeV/nucleon. Results: Excitation functions for five reaction products populated via complete and/or incomplete fusion processes in the O16 + Te130 system have been measured. Measured cross-sections have been compared with the predictions of the statistical model code pace4. A significant enhancement in the measured excitation functions compared to theoretical predictions for α-emitting channels has been observed and is attributed to incomplete fusion processes. The relative strength of incomplete fusion has been found to increase with projectile energy. In the case of the Xe133(3αn) channel, the isomeric cross-section ratios have been deduced and found to increase rapidly with beam energy, indicating the importance of imparted angular momentum. The angular momentum at different energies has also been calculated. The analysis of the data indicates that incomplete fusion is associated even for angular momentum values smaller than the critical angular momentum for complete fusion. The results have been discussed in terms of the α-cluster structure of the projectile for various fusion reactions. Conclusions: It may be concluded that, apart from complete fusion, incomplete fusion processes are of greater importance even at energies as low as ≈3-6 MeV/nucleon, where fusion evaporation channels are expected to be dominant. The measured isomeric cross-section ratio for the dominant incomplete fusion channel is found to increase with energy. Analysis of the data indicates that the incomplete fusion contribution becomes significant even for values of imparted angular momentum ℓ<ℓcritical also, contrary to SUMRULE model predictions.