Non - resonant direct p - and d - wave neutron capture by 12 C

Discrete γ-rays from the neutron capture state of 13C to its low-lying bound states have been measured using pulsed neutrons at En = 550 keV. The partial capture cross sections have been determined to be 1.7±0.5, 24.2±1.0, 2.0±0.4 and 1.0±0.4 μb for the ground (J = 1/2−), first (J = 1/2+), second (J = 3/2−) and third (J = 5/2+) excited states, respectively. From a comparison with theoretical predictions based on the non-resonant direct radiative capture mechanism, we could determine the spectroscopic factor for the J = 1/2+ state to be 0.80 ± 0.04, free from neutron-nucleus interaction ambiguities in the continuum. In addition we have detected the contribution of the non-resonant d-wave capture component in the partial cross sections