The cross sections for the binary fission of 197Au, 181Ta and 209Bi targets induced by 11B ions were measured at intermediate energies. The fission products cross sections were studied by means of activation analysis in off-line regime observed gamma-ray spectra. The fission cross section is reconstructed on the basis of charge and mass distribution of the fission products.
Mechanism of nuclear reactions on 197Au induced by 11B ions at energies above Coulomb barrier was studied by induced-activity method and gamma-spectroscopy. The cross sections of the reaction fragments from 197Au induced by 11B ions were measured at bombarding energies 137.5 and 255.5 MeV. The fission process was investigated by using multimodal fission approach at the energy 137.5 MeV, and pure symmetric distribution at 255.5 MeV. It was observed that the transferred linear momentum provides the information on the initial projectile-target information. The fissility for both fission reactions under study was deduced from measured fission cross section using the total inelastic cross section. Comparison with proton-induced fission shown, that the linear momentum transferred to the fissile system depends on the probe.
The complete and incomplete fusion cross sections for $^{7}$Li+$^{124}$Sn reaction were measured using online and offline characteristic $gamma$-ray detection techniques. The complete fusion (CF) cross sections at energies above the Coulomb barrier were found to be suppressed by $sim$ 26 % compared to the coupled channel calculations. This suppression observed in complete fusion cross sections is found to be commensurate with the measured total incomplete fusion (ICF) cross sections. There is a distinct feature observed in the ICF cross sections, i.e., $textit{t}$-capture is found to be dominant than $alpha$-capture at all the measured energies. A simultaneous explanation of complete, incomplete and total fusion (TF) data was also obtained from the calculations based on Continuum Discretized Coupled Channel method with short range imaginary potentials. The cross section ratios of CF/TF and ICF/TF obtained from the data as well as the calculations showed the dominance of ICF at below barrier energies and CF at above barrier energies.
The recent discovery of heavy-ion fusion hindrance at far sub-barrier energies has focused much attention on both experimental and theoretical studies of this phenomenon. Most of the experimental evidence comes from medium-heavy systems such as Ni+Ni to Zr+Zr, for which the compound system decays primarily by charged-particle evaporation. In order to study heavier systems, it is, however, necessary to measure also the fraction of the decay that goes into fission fragments. In the present work we have, therefore, measured the fission cross section of 16O+197Au down to unprecedented far sub-barrier energies using a large position sensitive PPAC placed at backward angles. The preliminary cross sections will be discussed and compared to earlier studies at near-barrier energies. No conclusive evidence for sub-barrier hindrance was found, probably because the measurements were not extended to sufficiently low energies.
An experimental overview of reactions induced by the stable, but weakly-bound nuclei 6Li, 7Li and 9Be, and by the exotic, halo nuclei 6He, 8B, 11Be and 17F on medium-mass targets, such as 58Ni, 59Co or 64Zn, is presented. Existing data on elastic scattering, total reaction cross sections, fusion processes, breakup and transfer channels are discussed in the framework of a CDCC approach taking into account the breakup degree of freedom.
Isospin diffusion is probed as a function of the dissipated energy by studying two systems $^{58}$Ni+$^{58}$Ni and $^{58}$Ni+$^{197}$Au, over the incident energy range 52-74AM. Experimental data are compared with the results of a microscopic transport model with two different parameterizations of the symmetry energy term. A better overall agreement between data and simulations is obtained when using a symmetry term with a potential part linearly increasing with nuclear density. The isospin equilibration time at 52 AM{} is estimated to 130$pm$10 fm/$c$.
N. A. Demekhina
,G. S. Karapetyan
,A. R. Balabekyan
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(2014)
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"Complete and incomplete fusion competition in 11B-induced fission reaction on medium mass targets at intermediate energies"
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Gayane Karapetyan
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