Study Of Particle Emission Mechanisms In ¹²C Fragmentation Reaction At 95 MeV/nucleon

Intermediate energy heavy-ion collision is one of the frontier of contemporary nuclear physics.In intermediate energy heavy-ion collisions?a few tens of MeV/u to a few hundreds of MeV/u?,the Fermi motion of nucleon and many-body correlation,which have strong impact on the collision dynamics and on the final results,are very important research objectives of contemporary nuclear physics.The emission of light charged particles and the formation of intermediate mass fragments are useful probes to investigate these two effects.Based on the modified version of Antisymmetrized Molecular Dynamics models?AMD?,the particle emission mechanisms in ¹²C+¹²C system at 95 MeV/nucleon are studied in this thesis.The impact of these two effects on the particle emission are also discussed.The main conclusions are as follows:1)Using AMD-FM to study the particle emission mechanisms in ¹²C+¹²C?The study of nucleon Fermi motion?Based on the existing experimental data of ¹²C+¹²C at 95 MeV/nucleon,microscopic transport models?CoMD,AMD,and AMD-FM?are used to calculate the angular distributions and energy spectra for light charged particles and intermediate mass fragments.The detailed comparisons are made between the experimental data and simulated results.it is found that the experimental energy spectra and angular distributions are well reproduced by the AMD-FM calculations for light charged particles with Z?2,especially for the IV source component in the energy spectra.However,the PLF component of all LCP's are slightly overpredicted.For the production of intermediate mass fragments,the simulated angular distributions with AMD and AMD-FM are very similar to each other at??15°,but those of AMD-FM show larger yields at larger angles by a factor of 2-10.The further investigation on the³He and ⁴He energy spectra shows that the majority of ³He particles originate from the primary process,and the contribution from the sequential decay process is very small.The Fermi motion taken into account in the two-nucleon collision process increases the Pauli-allowed NN collisions.This increase enhances the nuclear stopping and affects the angular distributions and energy spectra of emitted particles.2)Using AMD-Cluster to study the particle emission mechanisms in ¹²C+¹²C?the effect of cluster correlation?Based on the existing experimental data of ¹²C+¹²C at 95 MeV/nucleon,the impact of cluster correlations has been studied in the intermediate mass fragment emission in ¹²C+¹²C at 95 MeV/nucleon,using modified Antisymmetrized molecular dynamics model?AMD-Cluster?simulations.In AMD-Cluster,the cluster correlation is introduced as a process to form light clusters with A?4 in the final states of a collision induced by the nucleon-nucleon residual interaction.Also the correlations between the light clusters are considered to form light nuclei with A?9.This extended version AMD reproduces the global characteristic of light charged particles and intermediate mass fragments emissions to some extent.In particular,not only light clusters but also many of light nuclei with A?9 are emitted with very low excitation energies in the IV component in violent event.However,in detail,the IV components are significantly overpredicted for A=9–12 at?>20°.We found that it is very important to carefully handle the excitation energies of primary fragments and their statistical decay.The results indicate that the cluster correlation plays a crucial role for producing fragments at relatively low excitation energies in the intermediate heavy-ion collisions.