Circular polarization of γ-rays following the capture of polarized neutrons

Abstract

The circular polarization of γ-rays following the capture of polarized neutrons has been measured for some high intensity transitions in S 33, Ti 49, Fe 57, Ni 59, Y 90, Al 28, Cu 64 and N 15. The results are consistent with spin 1 2 for the 0.46 MeV level in Ni 59 and spin 2 for the 0.277 MeV level in Cu 64. The following spins are confirmed: 3 2 for the 3.22 MeV level in S 33; 3 2 and 1 2 for the 1.38 and 1.72 MeV levels in Ti 49; 2 for the 0.777 MeV level in Y 90. In N 15(25 ± 18)% of captures are found to occur in a state with spin 1 2 . In Fe 57, (49 ± 19)% of the intensity of the 7.64 MeV doublet γ-ray is found to belong to the ground state transition. In Al 28, information is obtained relating the mixture of spins in the capturing state and multipole mixtures and relative intensities of the components of the 7.72 MeV doublet. The results are compared with the predictions of nuclear models and theories of thermal neutron capture.