Ranges of Particles Emitted in the Disintegration of Boron and Lithium by Slow Neutrons

Abstract

I HAVE determined the ranges of particles emitted during disintegration of ¹⁰B and ⁶Li by slow neutrons, using a boron or lithium-coated ionization chamber connected with a Hoffmann electrometer. The ranges were deduced from the position of angles on the curves representing the ionization as a function of the pressure. The chamber filled with air was a brass cylinder of 8 cm. inner diameter and 10 cm. height. In the case of boron, pure finely powdered boron mixed with some water was distributed over the inner walls of the chamber; the density of the layer after evaporation of water was 2 × 10³ gm./cm.². In the case of lithium, lithium hydroxide made insoluble by heating at a high temperature was spread over the surface in an analogous manner with the same density as before. About 10 millicuries of polonium mixed with beryllium were used as source of neutrons, and the chamber was surrounded with a large cylindrical block of paraffin wax for slowing down the neutrons.