Excitation functions were measured for the 55 Mn(n,2n) 54 Mn, 55 Mn(n,α) 52 V, 63 Cu(n,α) 60 Co, 65 Cu(n,2n) 64 Cu, and 65 Cu(n,p) 65 Ni reactions from 13.47 to 14.83 MeV. The experimental cross sections are compared with the results of calculations including all activation channels for the stable isotopes of Mn and Cu, for neutron incident energies up to 50 MeV. Within the energy range up to 20 MeV the model calculations are most sensitive to the parameters related to nuclei in the early stages of the reaction, while the model assumptions are better established by analysis of the data in the energy range 20-40 MeV. While the present analysis has taken advantage of both a new set of accurate measured cross sections around 14 MeV and the larger data basis fortunately available between 20 and 40 MeV for the Mn and Cu isotopes, the need of additional measurements below as well as above 40 MeV is pointed out.

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A large number of new measurements with the activation technique were performed for (n,2n) and neutron-induced Z = 1,2 reaction cross sections on the stable molybdenum isotopes in the energy range from 13.5 to 21 MeV. First results were obtained for the 92 Mo(n,2n) Mo(n,x) 97 Nb m , and 100 Mo(n,α) 97 Zr reactions, above 16 MeV. A significant number of high-accuracy 14 MeV measurements were performed which are in good agreement with the measurements above 16 MeV for reactions studied in both energy ranges. The rather complete database for the molybdenum isotopes was analyzed with two different sets of consistent model calculations: a local and a global approach. The global approach (a blind calculation with the TALYS code) provides a good overall description of the dominant reaction channels, although the (n,α) reactions for the heavy isotopes are overpredicted. The local approach (an adjusted calculation with the STAPRE-H code) describes the shapes and magnitudes of the excitation functions well from the reaction thresholds up to 21 MeV using a consistent parameter set, which was optimized based on all experimental information for the nuclei at hand and their immediate neighbors. The agreement between experimental and calculated data is, in general, good both at the maxima and at the tails of the excitation functions, and both for total activation cross sections of a particular channel and for cross sections leading to isomers, showing the viability of the level densities, the optical models, and the γ widths. Comparison of the two model calculations with the data indicates the relevance of an appropriate treatment for preequilibrium (PE) α-particle emission for the description of the data above 14 MeV. Comparison between the model calculations shows largely different PE deuteron emission contributions to the total ( Z = 1, A = 1) cross sections with an additional marked difference in energy dependence. This suggests that emission spectra around 20 MeV are required to establish the magnitude of the PE deuteron emission contribution to this process. New γ -ray strength functions were established by verification against average (n,γ ) data and were demonstrated to give good agreement with the measured isomer production cross sections.

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Excitation functions of the 58 Ni(n,p) 58 Co m,g reactions were measured in the energy range from 2 to 15 MeV. The energy dependence of the isomeric cross-section ratio Rϭ m /( m ϩ g ) is deduced from the measured data. The shape and magnitude of the R(E n ) function are described by model calculations using a consistent parameter set. Questions of the input level scheme were solved based on the accurate isomeric ratio measured at low energy region. The measured R-value prefers the mixing ratio value of Ϫ2.3 for the transition of the 52.8 keV state to the 24.9 keV state, over the Ϫ0.33 value. The transition has predominantly E2 multipolarity. ͓S0556-2813͑99͒02207-4͔ PACS number͑s͒: 24.60. Dr, 25.40.Ϫh, 28.20.Ϫv

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