Polarization of the neutrons from the Be 9( α, n 0)C 12 and [formula omitted] reactions

Abstract

The polarizations of the neutrons from the Be 9( α, n)C 12 reaction leading to the ground and first excited states of C 12 were measured as a function of neutron emission angle for several bombarding energies between 1.90 and 4.50 MeV. polarization of the neutrons was measured by scattering from a He 4 analyser in the form of a high pressure gas scintillator. Asymmetries in the scattering of the neutrons from the helium were measured with the aid of an electro-magnet which could rotate the polarization vector of the neutrons between the source and the scatterer. Values of the polarization as large as 40% were observed for the ground-state neutrons, while the maximum polarization of the excited-state neutrons was about 25%. In general, the polarizations vary appreciably with energy and angle.