Absolute calibration of spin -1/2 polarization

It is shown that the polarization P(θ,E) of spin-1/2 particles scattered from particles without spin must reach the value P = 1 at some point (θ₁, E₁), if the scattering amplitudes fullfill certain conditions at two other energies E₀ < E₁ and E₂ > E₁. As examples, nucleon-⁴He and ³He-⁴He elastic scattering are investigated in this respect.

Present address: Physics Dept., Indiana University, Bloomington, Ind. 47401, USA.