Search for entrance channel effects in the decay of the 164Yb compound nucleus at E*~=54 MeV
Abstract
The existence of entrance channel effects in the decay of 164Yb*, formed at E*~=54 MeV in the reactions 16O+148Sm and 64Ni+100Mo is investigated. Evaporation residue cross sections, entry state γ-ray fold distributions as well as energy and angular distributions of exit channel selected charged particles were obtained for each reaction, using 4π detection systems for both particles and γ rays. In the 64induced reaction, the center-of-mass α-particle angular distributions were found to be symmetric around 90° indicating emission from a fully equilibrated compound nucleus. However, the corresponding angular distributions in the 16induced reaction show a forward component which exclusively affects the population of the αxn residue channels. The γ-ray fold distributions for the αxn and xn channels show differences depending on the entrance channel as reported previously for similar systems. These differences can be understood in terms of contributions from the equilibrium decay of incompletely fused 16O with 148Sm and the mapping of the compound nucleus spin distributions, obtained from realistic fusion models, to the evaporation residue γ-ray fold distributions. It is concluded that the initial population of the compound nucleus is the only reason for the observed differences in the decay of 164Yb* populated in these reactions.
- Publication:
-
Physical Review C
- Pub Date:
- December 1993
- DOI:
- 10.1103/PhysRevC.48.2881
- Bibcode:
- 1993PhRvC..48.2881B
- Keywords:
-
- 25.70.Gh;
- 25.70.Jj;
- 24.60.Dr;
- Compound nucleus;
- Fusion and fusion-fission reactions;
- Statistical compound-nucleus reactions