[en] A multi-step direct multi-step compound model free of the criticisms suffered by that of Feshbach, Kerman and Koonin is defined in terms of the statistical hypotheses made about the interaction matrix elements. The model is briefly described and discussed. Also described are our unsuccessful attempts to parametrize the level and transition strength densities needed in pre-equilibrium calculations in terms of their moments. (author)

[en] The Moldauer-Simonius theorem, that relates the modulus of the determinant of the average, optical S-matrix, to the average width and spacing of the compound nucleus resonances, is generalized to the multiclass resonances situation encountered in pre-equilibrium reactions. Corrections to the generalized M/S theorem are seen to be connected primarily to the width distribution of the widest doorway class. (Author)

[en] The manual of PREVU iterative code for plotting two-dimensional experimental and/or theoretical curves using nuclear data generated by TWOD code is presented. (M.C.K.)

[en] A simple model for the average S-matrix that describes heavy ion direct processes in the presence of absorption due to compound nucleus formation is developed. The fluctuation cross section and the fusion cross section are then calculated for deformed heavy ion systems where multiple Coulomb excitation is important. A simple expression for the fusion cross section valid for above-barrier energies is then obtained. The formula clearly displays the modification, due to Coulomb excitation, in the usual geometrical expression. (Author)

[en] Published in summary form only

[en] The implantation and testing of POLLA computer code which translates the paramters of solved resonance for low energy neutrons by Reich-Moore formalism into the equivalent Adler-Adler ones are discussed. The POLLA computer code was developed by Nuclear Data Center of Instituto de Estudos Avancados, in Brazil, to solve actinide resonance cross sections. (Author)

[en] The modifications made in the codes RECENT1 and POLLA1 are presented. The code RECENT2 is introduced. The graphical representations of the reconstructed cross sections from the Reich-Moore parameters by the codes RECENT2 and RECENT, version 1985, are compared. (author)

[en] The excitation of multiphonon giant resonances with heavy ions is discussed. The conventional theory, based on the use of the virtual photon number method in conjunction with the harmonic model is presented and its shortcomings are discussed. The recently developed model that invoke the Brink-Axel mechanism as an important contribution to the cross-section is discussed and compared to the conventional, harmonic model. The decay properties of these multiple giant resonances are also discussed within the same coherent + fluctuation model in conjunction with the hybrid decay model. It is demonstrated that the Brink-Axel mechanism enhances the direct decay of the states, as data seem to require. Comparison of our model with other recent theoretical works is presented

[en] The program RECENT, which reconstructs neutron cross sections from resonance parameters given in the ENDF/B format, was modified in order to include in its structure the Reich-Moore parametrization. (Author)

[en] The DDHMS (Double Differential Hybrid Monte-Carlo Simulation) model provides a suitable method for the calculation of multiple pre-equilibrium emission cross sections in γ or nucleon-induced reactions. ITA staff have extended this approach to produce exclusive cross sections, and have adopted a more appropriate Monte-Carlo sampling procedure to furnish a simplified, semi-classical version of the Feshbach-Kerman-Koonin multistep direct reaction model. Work continues to improve the physical content of the model, of which one aim is to describe the reactions in terms of the DDHMS method within the EMPIRE code.