Distribution of radiative strength from neutron capture by 239Pu

Abstract The (n, γ) reaction on 239 Pu has been used to populate states of 240 Pu. Discrete resonance-capture and resonance-averaged techniques have both been employed; the former provides an absolute normalization for the latter, 239 Pu presents a special problem: it is fissile and leads to behavior in resonance averaging which is quite different from what is encountered for non-fissile targets. The results show significantly different behavior for the M1 and E1 components of the capture radiation. While the E1's follow a giant-resonance behavior, with some diminished strength, the M1's show little or no energy variation, beyond the E 3 predicted from phase space.