ISSN:
1434-601X
Keywords:
25.70.Gh
;
25.70.Jj
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
Abstract Velocity distributions of heavy residuesA Res〉A tar,Z Res〉Z tar identified by means ofα spectroscopy, have been investigated at the velocity filter SHIP in reactions20Ne+208Pb at projectile energies E/A=8.6, 11.4 and 15.0 MeV/u. Besides products from complete or nearly complete fusion, characterized by velocity distributions peaking atν/ν CN≅0.8–1.0, heavy residues with mean velocities of about half of the compound nucleus velocity were observed. The Z-distribution of this component was found to peak atZ=87. It is interpreted as residues from fusion of target nuclei with projectile fragments produced by nearly symmetric break-up. The experimental results were compared with predictions of theoretical models: cross sections for incomplete fusion were calculated using the sum-rule model of Wilcynski et al., while residue cross sections were calculated using the evaporation code HIVAP. A fair agreement between experimental and calculated mass distributions of heavy residues and transferred projectile fragments is achieved if an energy dissipation of ≅23% (at E/A=8.6 MeV/u) and ≅8% (at E/A=11.4 MeV/u) of the incident projectile energy is introduced. The observed peak of theZ-distribution atZ=87 is predominantly effected due to a higher fission probability of products withZ〉87 during the deexcitation process and experimental limitations in the identification of products withZ≦86 by means of a spectroscopy, which cause a decrease of the observed production rates towards lowerZ.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01305889
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