Measurement of Cross Sections for the ²⁷Al(n, n′γ)²⁷Al Reaction Near Threshold

Cross-section ratios for production of 0.843-, 1.013-, and 2.209-MeV gamma rays at 55 deg by the ²⁷Al(n,n′γ)²⁷Al reaction relative to fast-neutron fission of ²³⁵U have been measured at intervals of ∼0.05 MeV from threshold up to ∼2.5 MeV, with an average neutron energy resolution of ∼0.08 MeV. These ratios and ENDF/B-IV fission cross sections were used to compute gamma-ray production cross sections. Gamma-ray angular distributions were measured at E_n = 1.112, 1.310, 1.512, 1.714, 1.914, 2.118, 2.310, and 2.512 MeV. These distributions were found to be isotropic within the experimental errors. The experimental results are compared with data from the literature and with results from optical/statistical model calculations of neutron inelastic scattering from aluminum.