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

Abstract

Radiative capture of polarized neutrons by 12C 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 energies E,=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 in 13C, a pronounced rise of the forward-backward asymmetry for the 12C(n, 7o) 13C reaction was observed indicating the presence of E2 capture interfering with direct and collective E1 capture. The direct-semidirect (DSD) model of radiative capture does not give a satisfactory description of the experimental results. 24.30.; 25.40. PACS: