Complete fusion and transfer reactions induced by 273 MeV⁴⁰Ar on¹⁵⁹Tb

Abstract

The nuclear reactions induced by 273 MeV⁴⁰Ar ions on a¹⁵⁹Tb target have been studied using recoil techniques and off-line X-ray spectrometry. The heavy products from fusionevaporation, fusion-fission, and transfer reactions can easily be separated on the basis of charge identification by X-ray spectrometry. The corresponding angular and range distributions are typical of each process. For each value of the atomic number, the average mass of the evaporation residues was determined with an uncertainty of ± 2 mass units (i.e.±1 %). The data were consistent with the assumption that 9±2 particles (nucleon and possibly some α-particles) were evaporated by the compound nucleus. The range measurements give results which agree with calculated values based on the total momentum transfer hypothesis within ± 8 %. The c.m. angular and energy distributions of transfer reaction products are typical of deep inelastic transfer reactions, with a contribution from partially damped events. The comparison of experimental data with the results of a calculation based on the model of Ngoˆand Hofmann in which statistical fluctuations are explicitly taken into account, indicates that the model reproduces correctly the position of the angular distribution maxima, for one- and two-charge transfer reactions, but underestimates the width of the angular distributions. Moreover, no transfer of more than two charges from the projectile to the target is predicted by this model while significant cross sections are observed experimentally.