Abstract
The dependence of fusion on the nuclear shell structure was investigated for the two reaction systems and where the nucleus has a closed neutron shell while the nucleus has a neutron number four neutrons less than the closed shell. Evaporation residues for these reaction systems were measured in the vicinity of the Coulomb barrier. The measured evaporation residue cross sections of and channels for the reaction system were considerably larger than those for the reaction system almost 100 times larger at the excitation energy region of 20–30 MeV. The fusion probabilities for these reaction systems were obtained from the evaporation residue cross sections with the aid of calculated survival probability and compared with those of the other reaction systems that make the same compound nucleus as the present systems. It was found that the fusion reaction occurs without hindrance, while that of is considerably hindered as commonly seen in the massive reaction system with the charge product of projectile and target. The present result suggests that the neutron shell closure promotes fusion.
- Received 31 October 2001
DOI:https://doi.org/10.1103/PhysRevC.65.054602
©2002 American Physical Society