The 90Zr(n, p)90Y reaction at En=98 MeV

Double-differential cross sections of the 90Zr(n, p) reaction have been measured at 98 MeV in the angular range 0°–30° for excitation energies up to 40 MeV. The spectra have been interpreted in terms of direct and multistep reactions. The contributions from the latter have been calculated using a statistical theory of multistep direct reactions. The direct parts of the spectra have been decomposed into their different multipole components by using peak-fitting and multipole-decomposition techniques, based on sample angular distributions calculated within the distorted-wave Born approximation. An extensive microscopic calculation based on the random-phase approximation has also been performed and the results are compared with the experimental data. A value Sβ+ = 1.7±0.2 is extracted for the Gamow-Teller strength, suggesting an occupancy ν2 = 0.09±0.01 for the 1g92 proton orbital. This value has been compared with recent results from (d, 3He) proton pickup and (e, e′p) knockout reactions.