Properties of the 4.038 MeV state in ²⁵Al

Abstract

The 4.038 MeV state in 25 Al, which is also the E p = 1.824 MeV resonance in the 24 Mg(p,γ) reaction, has been investigated using the 24 Mg(p,y) reaction. The γ-ray decay scheme is given and a limit of [Formula: see text], is obtained for the inelastic proton scattering width. Angular distribution measurements of deexcitation γ rays confirm previous values of radiation mixing ratios, but cannot remove the J π = 9/2 + , 5/2 + ambiguity in the spin–parity assignment. A Doppler shift attenuation measurement of the4.038 MeV deexcitation γ ray yields ƒ(τ) = 0.91 ± 0.02, corresponding to a lifetime of τ(4.038) = 22 ± 6 fs. The particle widths are derived using the lifetime and a previous measurement of the γ-ray yield at the 24 Mg, E p = 1.824 MeV resonance. On the basis of the particle width, arguments are given for a J π = 9/2 + assignment to the 4.038 MeV state.