Polarization of preequilibrium proton emission in the 93Nb + 14N reaction

Abstract

Spin polarization of protons emitted at 20° and 40° in the 93Nb + 14N reaction at 95 MeV has been measured by the double scattering method using a polarimeter particularly designed for protons having a continuous energy distribution.The result shows that the polarization is small for low-energy protons, but increases smoothly with the increase of proton energy, reaching around + 20 % at about 20 MeV in the center-of-mass system. Energy and angular distributions of protons measured in the same reaction indicate coexistence of equilibrium and preequilibrium components in the proton emission of interest, the fraction of the preequilibrium component increasing with the increasing proton energy. If we assume that protons emitted in equilibrium are completely unpolarized, and that the value of polarization ( P) for the preequilibrium component is independent of proton energy, the present result is consistent with P ⋍ + 22 % for the emission at 20° and P ⋍ + 38 % for the emission at 40°.The result is discussed in terms of the hot-spot model for precompound decay.