Radiation Effects from (n,α) Reactions in Boron Glass and Energy of the Reacting Neutrons

Abstract

The damage produced in neutron irradiated boron glass by the products of the (n,α) reaction appears as a pronounced optical birefringence. This birefringence is shown to be due to macroscopic stresses resulting from volume contraction of the glass. The variation of strain with depth from the glass surface is found to fit to a remarkable degree the space rate of decay of radiation of suitable velocity distribution and random direction. This permits the determination of the neutron velocity by one‐velocity theory, or of the most probable velocity for a Maxwellian neutron distribution; in addition the average volume contraction corresponding to a single neutron‐boron reaction is found to be equal to 3.6×10⁻¹⁹ cm³ per (n,α) reaction.