Double-differential (n, xp) and (n, x alpha) cross-section ratio measurements are performed at the 7-MV Van de Graaff accelerator laboratory for neutron energies between 2.0 and 15.6 MeV.: The following reaction rate ratios are measured: Ni-58(n, x alpha) to Al-27(n, x alpha), Ni-58(n, x alpha) to Ni-58(n,p), Cu-63(n, xp) to Al-27(n, x alpha), and Cu-63(n, xp) to Ni-58(n,p). Protons or alphas are detected by Delta E-Delta E-E telescopes under 14, 51, 79, 109, and 141 deg. The energy spectrum of the emitted particles and the angular yield distribution are measured. First, the measurements provide double-differential cross-section data for Al-27(n, alpha) and Ni-58(n,p) by normalization to the known total yield reference cross-section values. Subsequently, the reaction rate ratios of Ni-58(n, x alpha) and Cu-63(n, xp) to Al-27(n, alpha) or Ni-58(n,p) provide double-differential cross sections of Ni-58(n, x alpha) and Cu-63(n, xp) in b/(MeV. sr). The measured double-differential cross-section data, the particle energy spectra, the angular distributions, and the total yield cross-section data are compared with measured data from literature and with nuclear reaction model calculations performed at the Institute for Reference Materials and Measurements with the computer codes STAPRE-H and EXIFON.
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