E. Gadioli

Excitation functions for production of heavy residues in the interaction of12C with181Ta

The excitation functions for production of 21 isotopes and isomers of Au, Pt, Ir, Os and Re in the interaction of12C with181Ta from 54 to 98 MeV incident energy have been measured by the activation technique. The analysis of these data allows one to estimate the reaction cross-section and the cross-sections for complete fusion of12C and the incomplete fusion of8Be and α fragments with tantalum.

Boltzmann master equation theory of angular distributions in heavy-ion reactions

Abstract A generalization of the Boltzmann master equation theory in order to evaluate the angular distributions of the ejectiles emitted during the nucleon-nucleon interaction cascade which brings about the thermalization of the composite nucleus formed in the fusion of two heavy ions is discussed. The spectra of light ejectiles, up to α-particles, produced in many projectile-target combinations and at many different relative energies of the two ions are very reasonably reproduced.

Monte Carlo calculations using the Boltzmann Master Equation theory of nuclear reactions

Abstract The Boltzmann Master Equation theory of nuclear reactions is used to predict average multiplicities of particles emitted during the thermalization of an excited nucleus by a nucleon-nucleon interaction cascade. It is shown how it may also be used, together with a Monte Carlo calculation, to predict possible sequences of events and hence the cross-sections and other measurable observables of individual reactions.

Nuclear surface, mean field and isospin effects in Boltzmann master equation theory of pre-equilibrium reactions

Pre-equilibrium emission of nucleons and light charged particles is investigated in central collisions leading to the complete fusion of two heavy ions, within the Boltzmann master equation approach. Realistic nucleon momentum density distributions for both projectile and target nuclei are used and mean field effects are schematically introduced in the early stage of the reaction process. The isospin dependence of the calculation parameters is also discussed. Theoretical predictions of the spectra of the particles emitted both in symmetric and asymmetric interactions at incident energies of a few ten MeV/nucleon are in satisfactory agreement with the experimental findings.

Alpha particle emission in the interaction of

Abstract The results of measured inclusive double differential cross section of α particles emitted in the interaction of 12 C ions with 59 Co and 93 Nb at incident energies of 300 and 400 MeV are presented. The analysis of these data allows us to isolate the contributions of the different reaction mechanisms, thereby confirming previous conclusions of a comprehensive analysis of a large number of excitation function, forward recoil ranges and angular distributions of residues produced in the interaction of 12 C with a target nucleus in the same mass range. In particular, the probabilities associated with α-particle reemission following incomplete fussion processes have been reaffirmed. Several refinements to the theoretical model proposed in earlier studies of the interaction of 12 C with nuclei are presented.

^{12}

The continuous energy spectrum of secondary α particles emitted in (α, α′) reactions is interpreted in terms of an incoherent sum of α emissions after single and multiple α-nucleon collisions. The absolute yield of each contribution is evaluated utilising a generalisation of the Exciton Model and a satisfactory reproduction of the data is achieved. Also the angular distribution of α particles after a single α-nucleon interaction is satisfactorily reproduced. The possible role of processes involving interactions of the incident α with preformed αs is discussed.

C with

Abstract In this letter we discuss how one may evaluate the ejectile angular distributions with the Boltzmann Master Equation theory of nuclear reactions. The comparison of the calculations with the experimental ejectile double differential spectra is satisfactory confirming the validity of the theory. The possibility, offered by present calculations, of estimating how the nucleon momentum correlation disappears with increasing time, allows one to predict more accurately than with previous calculations the absolute value of the cross-sections for complex particle emission.

^{59}

We have observed the emission of intermediate mass fragments with a maximum yield at the Coulomb barrier energy in the interaction of 250 MeV 16O ions with 59Co. These emissions, which become dominant at emission angles larger than 20o, are explained by assuming that they are produced by nucleon coalescence during the thermalization of the composite nuclei produced in the complete and incomplete fusion of 16O with 59Co.

Co and

The experimental information on reactions induced by stopped ..pi../sup -/ absorbed in nuclei is critically reviewed. Evidence for the presence of ..cap alpha..-cluster absorptions is presented and arguments are given to show that approx. =25% of ..pi../sup -/ absorptions are of this kind. In the case of two-nucleon absorption, the existing experimental information concerning the ratio of n-p to p-p absorbing pairs is discussed. Calculations of particle spectra and residue spallation yield distributions that, in addition to two-nucleon absorption, include ..cap alpha..-cluster absorption are presented, and it is shown that a satisfactory reproduction of the data is achieved.