M. Cavinato

Monte Carlo calculations of heavy ion cross-sections based on the Boltzmann Master equation theory

Abstract We describe Monte Carlo calculations which use as input the double differential multiplicities of the particles emitted in small time intervals during the thermalization of excited nuclei. These multiplicities are evaluated by solving a set of coupled Boltzmann Master equations. The comparison of the experimental and the predicted exclusive spectra of the nucleons emitted in symmetric and asymmetric complete fusion heavy ion reactions at incident energies of a few tens of MeV / amu shows that the calculations reproduce accurately the data.

Angular distributions and forward recoil range distributions of residues created in the interaction of 12C and 16O ions with 103Rh

Abstract We have measured the angular distributions and the forward recoil range distributions of residues produced in the interaction of, respectively, 151, 228 and 402 MeV 12 C ions with 103 Rh and the forward recoil range distributions of residues produced in the interaction of 303 MeV 16 O ions with 103 Rh. These data have been successfully reproduced by a theory which assumes that the dominant mechanisms are complete and incomplete fusion of the projectile with the target and single nucleon transfers from the projectile to the target and predicts that, starting from an incident energy of about 250 MeV, a large fraction of the residues has a mass and charge very close to those of the target nucleus. This is because, at incident energies of a few hundred MeV, a large fraction of the kinetic energy of 12 C and 16 O is carried away by fast ejectiles which then leave behind the intermediate equilibrated nuclei with a rather small excitation energy and small forward linear momentum.

Collective excitations in 12C(e, e'p0) and 12C(e, e'n0) reactions at low momentum transfer

Abstract Predictions of coincidence 12 C(e, e′ x ) reactions at low momentum transfer are presented in a continuum self-consistent RPA theory with Skyrme forces. SK3 and SKM interactions are used. We investigate the role of different form factors and multipolarities in 12 C(e, e′p 0 ) and 12 C(e, e′n 0 ) angular distributions at forward and backward electron kinematics. The incident electron energy is E i = 126 MeV and ω = 22.5 MeV is the nuclear excitation energy. The sensitivity of 12 C(e, e′p 0 ) angular correlations in forward direction to monopole excitations is especially emphasized.

Intermediate mass fragment emission in Boltzmann master equation theory of pre-equilibrium reactions

A coalescence model originally proposed to account for the emission of nucleons and light particles in nuclear reactions is extended to account for intermediate mass fragment (IMF) emission. This theory uses a set of Boltzmann master equations to evaluate the time evolution of the occupation probability of nucleon states in the course of the de-excitation cascade during which the IMF are emitted. The internal structure of the IMF and the depletion of nucleon states due to IMF emission are explicitly considered. The theoretical predictions reproduce satisfactorily the experimental multiplicity spectra measured in central collisions of36Ar ions with197Au at incident energies of 35 MeV/nucleon.

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.

On the giant dipole resonance excitations in very hot nuclei

Abstract We discuss some of the ingredients necessary in the study of the excitation of the Giant Dipole Resonance in very hot nuclei.

The one-nucleon energy continuum in RPA-SK3 40Ca(e, é) nuclear responses at q⩽550 MeV/c

Abstract Longitudinal and transverse nuclear responses on 40 Ca (e, e′) electron scattering have been calculated at q ⩽550 MeV/ c in self-consistent HF-SK3 and RPA-SK3 nuclear models with the full treatment of the one-nucleon energy continuum. We analyze the quenching phenomena of the charge response in terms of he RPA-SK3 nuclear dynamics. The isoscalar and isovector longitudinal currents, which fulfil the continuity equation with the Skyrme RPA hamiltonian density, are derived. The missing strength is located in the isoscalar channel.

Complex fragment production in Kr-induced reactions at intermediate energies

Abstract Several features of complex fragment production at intermediate energies can be understood from the coupling of a dynamical description, which takes into account entrance-channel properties, and a statistical decay of equilibrated primary sources. We discuss this point using two different models for the dynamics, both based on the idea of the competition between mean field and two-body effects in this intermediate-energy range. The importance of a slow emission of large clusters in the de-excitation state is stressed, with the possibility of using a suitably extended evaporation code. Fragment yields and spectra are analysed for Kr-induced reactions on C, Al, Ti at 34.4 MeV/ A and on Au at 43 MeV/ A . The effects of a different equation of state (e.o.s.) used in microscopic calculations is analysed. A stiffer e.o.s. implies more stopping of the fragments. Finally, projectile-like fragments produced in the Kr+Au reaction at 200 MeV/ A are analysed. The predictions of the participant-spectator model are confirmed in this energy range.

Heavy ion interactions from Coulomb barrier to few GeV/n: Boltzmann Master Equation theory and FLUKA code performances

Results which have been recently obtained with the Boltzmann master equation and the FLUKA code in the analysis of heavy ion interactions at relative energies ranging from Coulomb barrier up to a few GeV/n are discussed.

Microscopic description of heavy ion collisions

Abstract We solve numerically the Boltzmann Nordheim Vlasov equation and apply it to calculate physical observables. The collision term is treated in the mean free path approximation and checked for an exactly soluble problem. We calculate particle spectra produced in heavy ion collisions around the Fermi energy. Finally, we propose a method to extract cluster formation from an average distribution in phase space just accounting for some minimal dynamical fluctuations coming from the collision term. We apply it to the study of the “spectator” region, which actually reveals a lot of interesting features.