Charge Yields Of Fission Fragments For Actinides

Nuclear fission is one of the most interesting topics in the past century.The development and utilization of nuclear energy is of great significance for national defense security and the normal operation of social economy.At present,the main way of nuclear energy utilization is through nuclear fission.One of the most interesting features of neutron or heavy-ion induced fission is that the mass and charge distribution of fission fragments are quite different for different nuclei.The study of fission fragment yield is not only important for nuclear engineering,but also important for understanding fission process,testing nuclear model,exploring the role of fission recycling as well as the structure of extremely neutron-rich nuclei,and studying the r-process in nuclear astrophysics.This thesis presents an effective method to describe the charge distribution of fission fragments for actinide nuclei based on the driving potential of fission system.Based on Skyrme energy density functional and Weizsacker-Skyrme nuclear mass formula,the driving potential closely related to the yield of fission fragments can be calculated clearly and quickly,and then combined with the mass distribution of nuclear fission,the charge distribution of fission fragments can be further obtained.We find that the measured charge distributions for a series of actinides can be reasonably well reproduced with the proposed method,especially for the odd-even staggering.If we remove the contribution of the pairing term in the calculations of Q value,we note that the odd-even staggering disappears,which clearly indicates that the pairing effect in fragments at their ground state plays a key role to the odd-even staggering in the charge distribution.We also find that the mass distributions of fission fragments which is used as the normalization factor can also influence the calculation results for the charge distribution.In addition,the influence of nuclear deformations on the charge distribution is also investigated.It is found that the quadrupole deformation of nucleus can significantly affect the interaction potential between fragments.The larger the quadrupole deformation is,the lower the potential barrier becomes,which results in a lower driving potential and thus a higher charge yield.