The polarization of MeV neutrons elastically scattered from 4He

The analyzing power of 4He for neutron elastic scattering has been measured at four angles between 200 and 800 (lab) throughout the energy range 1.5-6.0 MeV using a double-scattering method. The intense flux of polarized neutrons was generated via the reactions Pb(γ, n)→12C(n, n(pol.)12C, and the magnitude of the polarization of the neutron beam measured absolutely in a separate double-scattering experiment. Neutron energies were determined with a nanosecond time-of-flight spectrometer, and the generalized neutron spin-precession method was used to minimize systematic uncertainties. (Auth.)