Fusion evaporation-residue cross sections forSi28+40

Abstract

Velocity distributions of mass-identified evaporation residues produced in the Si+ Ca reaction have been measured at bombarding energies of 309, 397, and 452 MeV using time-of-flight techniques. These distributions were used to identify evaporation residues and to separate the complete-fusion and incomplete-fusion components. Angular distributions and upper limits for the total evaporation-residue and complete-fusion evaporation-residue cross sections were extracted at all three bombarding energies. The complete-fusion evaporation-residue cross sections and the deduced critical angular momenta are compared with earlier measurements and the predictions of existing models. The ratios of the complete-fusion evaporation-residue cross section to the total evaporation-residue cross section, along with those measured for the Si+ ' C and Si+ Si systems at the same energies, support the entrancechannel mass-asymmetry dependence of the incomplete-fusion evaporation-residue process reported earlier.PACS number(s): 25.70.Jj

Towards a unified description of evaporation-residue fusion cross-sections above the barrier

“…2 (fig. 5) [29] 16O+27Al [34] 32S+12C [39] 20Ne+26Mg [40] 20Ne+27Al [41] 35Cl+12C [42] 16O+40Ca [46] 28Si+28Si [48] 32S+24Mg [53] 19F+40Ca [55] 32S+27Al [54] 35Cl+24Mg [57] 23Na+40Ca [55] 28Si+40Ca [55,60] (4)) in the fusion region III is shown as full darkred curve in both panels. The darkgreen dash-dotted curve in inset is due to the same kind of fit to the fusion region II.…”

Mass-Asymmetry effects in heavy ion reactions: Complete fusion Vs incomplete fusion

“…Morgenstern et al [8] in his studies established the entrance-channel mass-asymmetry dependence of the ICF reaction, with the ICF probability being higher in a mass-asymmetric system than in a mass-symmetric system at the same relative velocity. Later, studies by Vineyard et al [9] and Chakrabarty et al [10] also supported the findings of Morgenstern et al [8]. …”

Energy dependence of fusion evaporation-residue cross sections in theSi28+Vineyard1, Mateja2, Beck3 et al. 1993Phys. Rev. CSelf Cite14070View full textAdd to dashboardCite

“…Absolute cross sections were determined by measuring the elastic scattering of tandem energy (76.5 MeV) Si ions from the ' C target at 0»b=5' -15' and comparing with the Rutherford scattering predictions. The experimental procedure has been described in more detail elsewhere [8,9]. At the three highest energies the velocity spectrum for each residue mass (12~A 39) was decomposed with a Gaussian fitting procedure [8,9] to determine the evaporation-residue and complete-fusion contributions.…”

“…Initially, data were taken at Si bombarding energies of 309, 397, and 452 MeV as part of a systematic study [8,9) of the energy and target dependence of the incomplete-fusion evaporationresidue process. Additional measurements were then performed at lower energies resulting in data extending over one of the largest energy ranges ever measured for a light system.…”