Calculated Cross Sections For Neutron Induced Reactions On Sup 19 F And Uncertainties Of Parameters

Nuclear model codes were used to calculate cross sections for neutron-induced reactions on 19F for incident energies from 2 to 20 MeV. The model parameters in the codes were adjusted to best reproduce experimental data and are given in this report. The calculated results are compared to measured data and the evaluated values of ENDF/B-V. The covariance matrix for several of the most sensitive model parameters is given based on the scatter of measured data around the theoretical curves and the long-range correlation error of measured data. The results of these calculations form the basis for the new ENDF/B-VI fluorine evaluation. 44 refs., 64 figs., 14 tabs.

Nuclear model codes were used to compute cross sections for neutron-induced reactions on both /sup 58/Ni and /sup 60/Ni for incident energies from 1 to 20 MeV. The input parameters for the model codes were determined through analysis of experimental data in this energy region. Discussion of the models used, the input data, the resulting calculations, extensive comparisons to measured data, and comparisons to the Evaluated Nuclear Data File (ENDF/B-V) for Ni (MAT 1328) are included in this report. 118 refs., 101 figs., 19 tabs.

Nuclear model codes were used to compute cross sections for neutron-induced reactions on /sup 52/Cr for incident energies from 1 to 20 MeV. The input parameters for the model codes were determined through analysis of experimental data in this energy region. Discussion of the models used, the input data, the resulting calculations, extensive comparisons to measured data, and comparisons to the Evaluated Nuclear Data File (ENDF/B-V) for Cr (MAT 1324) are included in this report. 103 refs., 67 figs., 12 tabs.

Nuclear model codes were used to compute cross sections for neutron-induced reactions on /sup 63,65/Cu, /sup 58,60/Ni, and 52Cr for incident energies from 1 to 20 MeV. The input parameters for the model codes determined through analysis of experimental data in this energy region. The models used, the input data, the resulting calculations, and comparisons with measured data are discussed. 15 refs.

Nuclear model codes were used to compute cross sections for neutron-induced reactions on /sup 40/Ca for incident energies from 20 to 40 MeV. The input parameters for the model codes were determined through analysis of experimental data in this energy region. Computed cross sections along with emission spectra for each product were combined into an Evaluated Nuclear Data File (ENDF) using the proposed format for charged-particle reactions. Discussion of the models used, the resulting calculations, and the final evaluated data file are presented.

Nuclear model codes were used to compute cross sections for neutron-induced reactions on both /sup 63/Cu and /sup 65/Cu for incident energies from 1 to 20 MeV. The input parameters for the model codes were determined through analysis of experimental data in this energy region. Discussion of the models used, the input data, the resulting calculations, extensive comparisons to measured data, and comparisons to the Evaluated Nuclear Data File (ENDF/B-V) for Cu (MAT 1329) are included in this report.

Neutron-induced cross sections of /sup 53/Cr have been calculated in the energy regions from 1 to 20 MeV. The quantities obtained are the cross sections for the reactions (n, n'.gamma.), (n,2n), (n, np), (n, n.cap alpha.), (n, p.gamma.), (n, pn), (n, .cap alpha gamma.), (n, .cap alpha.n), (n, d), (n, t), (n, /sup 3/He), and (n, .gamma.), as well as the spectra of emitted neutrons, protons, alpha particles, and gamma rays. The precompound process was included above 5 MeV in addition to the compound process. For the inelastic scattering, the contribution of the direct interaction was calculated with DWBA. 36 refs., 23 figs., 11 tabs.

The Surrogate nuclear reactions method, an indirect approach for determining cross sections for compound-nuclear reactions involving difficult-to-measure targets, is reviewed. Focusing on cross sections for neutron-induced reactions on actinides, we review the successes of past and present applications of the method and assess its uncertainties and limitations. The approximations used in the analyses of most experiments work reasonably well for (n, f) cross sections for neutron energies above 1-2 MeV, but lead to discrepancies for low-energy (n, f) reactions, as well as for (n, [gamma]) applications. Correcting for some of the effects neglected in the approximate analyses leads to improved (n, f) results. We outline steps that will further improve the accuracy and reliability of the Surrogate method and extend its applicability to reactions that cannot be approached with the present implementation of the method.