Reactions of Alpha Particles with Iron-54 and Nickel-58

The excitation functions for the (α, p), (α, n), (α, pn), (α, 2n), (α, 2pn), and (α, p2n) reactions of Fe⁵⁴ and the (α, α^'p), (α, α^'n), (α, α^'pn), and (α, α^'2n) reactions of Ni⁵⁸ have been determined for alpha-particle energies up to 40 Mev. A large preference for proton emission is observed. At the maxima in the excitation functions, these ratios were obtained: σ(α, p)σ(α, n)=3.1; σ(α, pn)σ(α, 2n)=70; σ(α, α^'p)σ(α, α^'n)=6; σ(α, 2pn)σ(α, p2n)=6.3 (at 40 Mev); and σ(α, α^'pn)σ(α, α^'2n)=140 (at 40 Mev). These results are discussed in terms of the compound-nucleus model. A value of r₀=1.7 fermis is required to fit the low-energy portion of the observed "total" cross section with total reaction cross section calculated from continuum theory.