Theoretical Study On The Influence Of Nuclear Potential On Coupled Channel Effect

The near barrier and sub-barrier fusion reactions are an effective probe for nuclear structure,and it is also an important tool to reveal the basic problem of multi-dimensional quantum penetration.When the interaction time of the projectile-target system is approximately equal to the nucleon transmission as well as the time of the nuclear collective motion,the freedom of motions that characterizing the nuclear structure properties will be strongly coupled with those freedom of the relative motion.Therefore,the effect of the coupled channel effect must be taken into account to describe near barrier and sub-barrier fusion reactions.Because near barrier fusion reactions,especially the sub-barrier reactions,must be completed within quantum tunneling,the nuclear potential must be calculated efficiently in order to obtain the corresponding penetration coefficient.Using the energy dependent Woods-Saxon(EDWSP)model,the fusion potential barriers of the three systems are calculated firstly.The results show the conclusions as follows:(1)the fusion barrier for the system with stronger symmetry changes more obviously;(2)the role of neutron transfer channel in coupled channel effect,for asymmetric system,is more significant than that of the symmetric one.The results from fusion excitation functions show that(1)the effect of projectile's vibration on the fusion process can be ignored for the asymmetric system;(2)the effect of target's vibration on fusion process is greater than that of projectile's vibration,which suggests that the fusion process of the reaction system is more affected by the vibration of the target;(3)the different phonon coupled modes can only reproduce the reaction cross section in a local energy region.The results from barrier distribution present that the peak of reaction potential barrier for two systems with different symmetry go on in the opposite energy region,so that the EDWSP model can only reproduce the experiments above the fusion barrier.We also study the action of adiabatic potential on coupled-channel effect by choosing different systems,the results show that the potential energy of the three system calculated by the adiabatic model is very similar to the burst potential before contact point.When the contact point is crossed,there is a shallow trough in the burst potential curve of the symmetric system,and the corresponding trough of the system with strong asymmetry is deeper than that of the symmetric system.The coupled channel calculation without damping effect can better reproduce the near base and the fusion cross section of the symmetric system,but it overestimates the cross section of the barrier,which shows the necessity of considering damping effect to study the coupled channel effect in fusion reaction.