[en] The measured cross sections of 14 MeV (n,p) and (n,α) reactions for nuclei with mass number larger than 100 are analyzed in terms of the pre-equilibrium exciton model and effective Q value, which is a smooth function of mass number and atomic number and is free from fluctuations near closed shells. Deviations from 1.0 of the ratios of experimental to theoretical cross sections calculated using the effective Q values Q/sub e/ for the (n,p) reaction and the average Q values (Q/sub t/+Q/sub e/)/2 for the (n,α) reaction are markedly reduced as compared with the use of the true Q values Q/sub t/. (author)

No abstract available

[en] Volume integrals of central optical potentials for scatterings of deuterons, ³He and α-particles from nuclei are discussed. The corrections factors of volume integrals of ³He real central optical potentials to those estimated from nucleon-nucleus folded potentials are about 30 % at the incident energy of 10 -- 30 MeV/nucleon and approach to negligibly small values at 70 -- 100 MeV/nucleon region. Volume integrals of imaginary central potentials are also discussed. (author)

[en] Multi-step direct-reaction theory proposed by Tamura et al. has been applied to continuous spectra of the 14 MeV (n, α) reaction with some modifications. Calculated results reproduce well the experimental energy and angular distributions of the 14 MeV (n, α) reactions. (author)

[en] The energy spectrum and angular distributions of protons emitted from the ⁹³Nb(n,p) reaction have been measured at a bombarding energy of 14.1 MeV with a position-sensitive counter-telescope. The energy spectrum is well explained by the sum of the spectra calculated on the basis of the preequilibrium and statistical evaporation models. The angular distributions are successfully reproduced by means of the generalized exciton model. The multistep direct reaction model indicates a little discrepancy in the absolute cross section in spite of general agreement in the shape of the angular distributions

[en] The energy spectra of particles emitted from (p,α) and (p,p') reactions on nuclei around magic number with 18 MeV protons were measured in order to clarify the shell and odd-even effects in the preequilibrium processes. From the experimental results, it was found that there exist no appreciable shell and odd-even effects in energy spectra for the preequilibrium (p,α) and (p,p') reactions. The energy spectra for (p,n), (n,p), (p,α), (n,α), (p,p') and (n,n') reactions were analyzed in terms of the preequilibrium exciton model introducing effective Q-values, the pairing correlation, and the modified uniform spacing model in which the uniform spacing model is modified so as to have a wide spacing at the magic number. The calculated spectra using the above model show good agreement with the experimental ones. The fine structures of the energy spectra for the (p,α) reactions on nuclei around atomic number 50 can be qualitatively explained using the three-nucleon pickup model under the assumption that the states excited in the (p,α) reaction are formed by the coupling of two-neutron hole states excited in the (p,t) reaction and one-proton hole states excited in the (d,³He) reaction. The similar three-nucleon pickup model can explain qualitatively the fine structures of the energy spectra for the (n,α) reactions on nuclei around neutron numbers 50 and 82. The energy spectra for the (p,d) reaction on Mo isotopes were also measured and analyzed. (author)

[en] Multi-step direct-reaction theory proposed by Tamura et al. has been applied to continuous spectra of the 14 MeV (n, n') reaction with some modifications. Calculated results reproduce well the experimental 14 MeV (n, n') data for both the energy and angular distributions. (author)

[en] Measurements of double differential charged-particle emission cross sections are reported for proton-induced reactions on several medium-heavy nuclei in the bombarding proton energy range from 10 to 20 MeV. Some results of analyses based on preequilibrium models are summarized. (author)

[en] The neutron energy spectra from the (p,n) reaction on /sup 90,91,92,94/Zr, /sup 92/,94,95,96,97,98,100Mo, and /sup 110/Pd with 25 MeV protons and /sup 90,91,92,94/Zr with 18 MeV protons are analyzed in terms of the preequilibrium exciton model introducing effective Q values, the pairing correlation, and the modified uniform spacing model in which the uniform spacing model is modified so as to have a wide spacing at the magic number. For all these targets, the calculated spectra using the above model for 25 MeV protons show good agreement with the experimental ones not only on the absolute cross sections in the neutron energy region of 12--18 MeV, but also on the observed spectra with pronounced structures in the neutron energy region higher than 18 MeV

[en] The multi-step direct-reaction theory proposed by Tamura et al. was applied, with some modifications, to the continuous spectra of 14 MeV (n,n') reaction. The calculated results reproduced well the experimental 14 MeV (n,n') data for both the energy and angular distributions with a reasonable normalization procedure. (orig.)