Theoretical Studies Of Entrance Channel Effect Of Prescission Particles Emission With Prescission Particle Emission And Evaporation Residue Cross Section

HIRFL-CSR accelerator system can/will provide heavy-ion beams with energies fromseveral MeV/u up to2.3GeV/u. The synthesis of the superheavy nuclei (SHN) and the studyof the asymmetric nuclear matter equation of state (EOS) are two of the proposed physicsprograms about it. Before pursuing the experimental research, the detailed theoretical studywhich aimed at the related physics is important. This thesis is devoted to the theoretical studyon the two proposed physics programs at HIRFL-CSR.In this thesis, we firstly make an introduction about the research status of superheavyelement (SHE). Next we describe the main problem for the study of SHE, namely, it isnecessary to search a best combination between projectile and target nuclei in order to findout a new reaction mechanism, due to there a gap of several neutrons to arrive in the steadyisland of SHE with present synthesis mechanics and combinations of projectile and targetnulei. Next, we pay attention to the nuclear dissipation and its probes, the prescission particlemultiplicity, and make a detailed description for the two quantities. In order to understand thefocus of our works, we also describe the theoretical models (the combined dynamical andstatistical model: CDSM and its modified version) and pathwise analysis method used in thepresent thesis in second chapter. Next, in chapter3and4we carry out simulations for tworeactions with different asymmetry parameters which produced a same compound nucleus,namely,16O+181Ta and19F178Hf, and make a deep discussion about the entrancechannel effect with two quantities, i.e. the emission of prescission particle and evaporationresidue section, and the results show as follows:(1) The results show that the prescission particle multiplicities descend with the massasymmetry decreasing from the ground state to saddle point, and the inverse lawappears in the interval between the saddle point and scission point.(2) The fusion section depends on the asymmetry parameter of entrance channel for twodifferent reaction channels which produce the same compound nucleus, The moreasymmetry parameter is, the larger the fusion section behaves. Furthermore, thedifference of fusion section decreases with increasing projectile bombarding energy,and it disappears until certain energy. (3) For a certain reaction, we can gain larger evaporation residue section with a weakerdeformation dependence of level density parameter under the condition of the samenuclear dissipation. On the other hand, with the same level density parameter, we canget the larger evaporation residue section using OBD dissipation than SPS one. Itworth pointing out that the conclusion doesn’t depend on the asymmetry parameterof entrance channel.