Collision Lengths of Neutral, Penetrating-Shower-Producing Cosmic Radiation in Light and Heavy Water

Abstract

The collision length, $L_c$, of neutral penetrating-shower-producing cosmic radiation incident through a reinforced concrete roof of thickness 25 g/${\mathrm{cm}}^2$ at Los Alamos, New Mexico, altitude 2280 meters, was measured in light and heavy water. The values obtained were, for ${\mathrm{H}}_2$O, $L_c=113\mathrm{}\pm 10$ g/${\mathrm{cm}}^2$ and for ${\mathrm{D}}_2$O, $L_c=123\mathrm{}\pm 10$ g/${\mathrm{cm}}^2$. Equal masses of oxygen per unit area in the ${\mathrm{H}}_2$O and ${\mathrm{D}}_2$O absorbers were used for a determination of the difference between the collision cross sections of the deuteron and of the proton for the incident particles. The value obtained for this difference was ${\sigma }_D-{\sigma }_P=13\mathrm{}\pm 15$ mb.