Statistical γ-Decay ins-dShell Nuclei

Abstract

The γ-decay following the 27Al(τ, α), 27Al(τ, τ) and 27Al(τ, t) reactions has been studied using Eτ = 45 MeV. For all three reactions a maximum mean γ-ray multiplicity of ⟨Mγ⟩ = 1.8 ± 0.2 is observed, in good agreement with the Fermi gas model. The variation of ⟨Mγ⟩ with excitation energy for the 27Al(τ, τ)27Al reaction, however, shows considerable deviations from the decay pattern expected for a statistical system. From a comparison with other reaction channels, we suggest that the selectivity in the excitation of states in the inelastic process is responsible for this non-statistical pattern.