Range-Energy Relation and Masses of the New Particles

Abstract

The accuracy to which the masses of most of the new unstable particles can be determined is now limited principally by the uncertainty in the range-energy relations at large velocities. The extent of this uncertainty is indicated, and the available data are re-examined to try to find the best relations to use. In particular, shell corrections are applied to the Sachs-Richardson data, and the mean excitation potentials for 9 elements are determined. The evidence for Al, Cu, and emulsion indicates that the mean excitation potentials are not velocity dependent, and that they may be considerably larger than the values commonly used.