On the influence of the mean-free-path parameter on intranuclear cascade calculations

In a recent letter GINOCCHIO and BLANN (2) compared results of intranuclear cascade model (ICM) calculations obtained either with a nucleon mean-free-path (mfp) in nuclear matter corresponding to free 3~-2C scattering cross-sections, or with a four times longer mfp. The latter assumption was reported to give far poorer agreement with the experimental data; and this conclusion was reported as evidence in favour of the use of the shorter mfp values in pre-equilibrium decay models, whose alternate formulations have been lately discussed at some length (2.6). We maintain tha t ICI~[ calculations performed with the free ~ ~ scatter mfp in general do not afford an accurate reproduction of the excitation functions of reactions induced by protons of some tens of MeV, and of the energy integrated spectra of the emitted particles. In fact, published results of ICM calculations have shown a systematic tendency to underestimate the emission of high-energy particles, and to overestimate compound-nucleus production. We made this statement, which agrees with an opinion already expressed by MILLER (D, on the basis of the findings of several works cited in ref. (2). Our belief is further supported by other results of BERTINI et al. (S) (e l . Specifically fig. 4 thereof), and even by the figures reported by the authors of ref. (1). However, in spite of such inadequacies of the ICM calculations, the model seems to retain a good measure of appeal as an intui t ive tool much in use for practical purposes

Comprehensive study of the reactions induced by 12C on 103Rh up to 33 MeV/nucleon

Abstract Fifty-three excitation functions for the production of radioactive residues in the interaction of 12C with 103Rh have been measured from the Coulomb barrier up to 400 MeV by means of the activation technique. These excitation functions have been analyzed considering complete fusion, incomplete fusion of 8Be and α-particle fragments and, above about 200 MeV, the transfer of either one proton or one neutron from 12C to 103Rh. The emission of pre-equilibrium particles during the thermalization of the excited composite nuclei formed in all these processes and, in the case of 8Be and α incomplete fusion, also the re-emission of α-particles after a mean-field interaction or a few interactions with the target nucleons have been taken into account

Nuclear Thermalization

The thermalization of a composite nucleus formed when two heavy ion fuse, that is the transformation of the orderly translational motion energy of the two ions into chaotic, thermal motion energy may be described by a set of Boltzmann master equations which allow one to calculate the time evolution of the single nucleon energies within the composite nucleus. The theoretical assumptions and the results of the analysis of the experimental data are discussed

Boltzmann master equation theory of angular distributions in heavy ion reactions

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 \u3b1-particles, produced in many projectile-target combinations, and at many different relative energies of the two ions are very reasonably reproduced

Ejectile angular distributions in Boltzmann master equation theory of nuclear reactions

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

Monte Carlo calculations using the Boltzmann master equation theory of nuclear reactions

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