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Nuclear Theory·nucl-th

Monday·July 4, 2016

4 papers—3 primary·1 cross-listed

All4Primary3Cross-lists1
  1. 01

    Microscopic Description of Diffractive Deuteron Breakup by He-3 Nuclei

    Valery Kovalchuk

    A microscopic formalism for describing observed cross sections for deuteron breakup by three-nucleon nuclei was developed on the basis of the diffraction nuclear model. A general formula that describes the amplitude for the reaction d+3He->3He+p+n and which involves only one adjustable parameter was obtained by using expansions of the integrands involved in terms of a Gaussian basis. This formula was used to analyze experimental data on the exclusive cross sections for deuteron breakup by He-3 nuclei at the projectile energy of 89.4 MeV. The importance of employing, in calculations, a deuteron wave function that has a correct asymptotic behavior at large nucleon-nucleon distances was demonstrated.

    nucl-thPhys.Atom.Nucl.(2016)·1 citation
  2. 02

    Late Time Emission of Prompt Fission Gamma Rays

    P. Talou · T. Kawano · I. Stetcu · J. P. Lestone · E. McKigney · M. B. Chadwick

    The emission of prompt fission rays within a few nanoseconds to a few microseconds following the scission point is studied in the Hauser-Feshbach formalism applied to the deexcitation of primary excited fission fragments. Neutron and -ray evaporations from fully accelerated fission fragments are calculated in competition at each stage of the decay, and the role of isomers in the fission products, before -decay, is analyzed. The time evolution of the average total -ray energy, average total -ray multiplicity, and fragment-specific -ray spectra, is presented in the case of neutron-induced fission reactions of U and Pu, as well as spontaneous fission of Cf. The production of specific isomeric states is calculated and compared to available experimental data. About 7% of all prompt fission rays are predicted to be emitted between 10 nsec and 5 sec following fission, in the case of U and Pu reactions, and up to 3% in the case of Cf spontaneous fission. The cumulative average total -ray energy increases by 2 to 5% in the same time interval. Finally, those results are shown to be robust against significant changes in the model input parameters.

    nucl-thnucl-exPRC(2016)·32 citations
  3. 03

    To fission or not to fission

    Krzysztof Pomorski · Bozena Nerlo-Pomorska · Fedir A. Ivanyuk

    The fission-fragments mass-yield of 236U is obtained by an approximate solution of the eigenvalue problem of the collective Hamiltonian that describes the dynamics of the fission process whose degrees of freedom are: the fission (elongation), the neck and the mass-asymmetry mode. The macroscopic-microscopic method is used to evaluate the potential energy surface. The macroscopic energy part is calculated using the liquid drop model and the microscopic corrections are obtained using the Woods-Saxon single-particle levels. The four dimensional modified Cassini ovals shape parametrization is used to describe the shape of the fissioning nucleus. The mass tensor is taken within the cranking-type approximation. The final fragment mass distribution is obtained by weighting the adiabatic density distribution in the collective space with the neck-dependent fission probability. The neck degree of freedom is found to play a significant role in determining that final fragment mass distribution.

    nucl-th1 citation

Affiliations

first authorsco-authorsvia INSPIRE