Measurements of fusion cross sections in the systems {sup 58,64}Ni +, {sup 78,86}Kr
- and others
We investigated the nuclear structure dependence of the sub-barrier fusion enhancement in heavy-ion induced reactions by studying the systems {sup 58,64}Ni + {sup 78,86}Kr at energies in the vicinity of the Coulomb barrier. These {sup 78,86}Kr selected because, similar to the Mo case discussed isotopes were above, there are strong changes in nuclear structure as a function of the neutron number. However, contrary to Mo, where the {open_quotes}softness{close_quotes} of the nucleus increases with higher neutron number, the most collective nucleus for the Kr case is the neutron-deficient {sup 78}Kr. The experiment was performed with Kr beams from the positive-ion injector using enriched {sup 78,86}Kr gas in the ECR ion source. The separation of evaporation residues from the elastically-scattered particles was achieved by using their difference in time-of-flight and magnetic rigidity in the gas-filled spectrograph. The excitation functions for the four systems were compared to coupled-channels calculations including inelastic excitations of one- and two-phonon states in projectile and target. For systems involving {sup 86}Kr, good agreement between theory and experiment is obtained, while for {sup 78}Kr + {sup 58,64}Ni an additional enhancement of the cross sections persisted at the lowest energies. It was found that this fusion enhancement correlates with the nuclear structure of the individual nucleus. Characterizing the structure of vibrational even-even nuclei by their restoring force parameter C{sub 2}, which can be calculated from the energy of the lowest 2{sup +} state and the associated B(E2) value, one observes that nuclei with small C{sub 2} values exhibit a large sub-barrier fusion enhancement, while nuclei with high values of C{sub 2} (usually closed-shell nuclei), show smaller fusion yields.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- OSTI ID:
- 166292
- Report Number(s):
- ANL-95/14; ON: DE96000985; TRN: 95:007970-0004
- Resource Relation:
- Other Information: PBD: Aug 1995; Related Information: Is Part Of Physics Division Annual Report, April 1, 1994--March 31, 1995; Henning, W.F.; PB: 207 p.
- Country of Publication:
- United States
- Language:
- English
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