Radiative capture of polarized neutrons by12C in the energy rangeE n=20?35 MeV

Abstract

Radiative capture of polarized neutrons by12C was investigated using a scintillating NE-213 target and three NaI detectors. Angular distributions of the capture gamma photons and analyzing powers were measured at laboratory angles of 55°, 90° and 125° and neutron energiesEinn=20 to 35 MeV. Capture photons and recoil nuclei were detected in coincidence, the photons being identified by measuring the time of flight and analyzing the pulse shape in the NaI detectors. In the energy range above the centre of the GDR in13C, a pronounced rise of the forward-backward asymmetry for the12C(n,γ0)13C reaction was observed indicating the presence ofE2 capture interfering with direct and collectiveE1 capture. The direct-semidirect (DSD) model of radiative capture does not give a satisfactory description of the experimental results.