ENERGY LOSS OF HIGHLY CHARGED PARTICLES PRODUCED BY FISSION AND BY COSMIC RAYS: III. THE LINEAR DENSITY OF DELTA RAYS. EXPERIMENTS

Abstract

Delta rays having an energy as low as 2–5 kev. have been counted along the tracks of mesons, protons, and α rays of low velocity, allowing the identification of each. Three methods are presented and applied to determine the efficiency ƒ of counting delta rays of various energies; measured values of ƒ vary between 0.05% at 2 kev. and 100–180% near 50 kev. The number of grains, and the energy distribution among visible delta rays, are analyzed. A new method of determining velocity, based on the analysis of the number of grains in the delta rays, is presented. In the Appendix, the effect of relativistic corrections is computed and discussed. It is small except at large velocities where comparison with experiment is difficult.