CXV. The anomalous scattering ofμ-mesons in lead

Abstract

A multi-plate cloud chamber has been operated at sea-level under a thick lead absorber and the scattering of penetrating particles—presumably μ-mesons—has been investigated. In common with the results of other workers, a component of scattering has been found which is not consistent with the distribution expected from simple Coulomb scattering from a nucleus in which the charge is distributed uniformly throughout the volume (‘solid’ nucleus). We find that the magnitude of this anomalous component is similar to that expected from the Coulomb interaction with a nucleus of effective radius much smaller than that of the ‘solid’ nucleus. Since it is very unlikely that the electrostatic charge of the nucleus can be considered to be concentrated at the centre of the nucleus, we conclude that the anomaly is probably due to a short range non-electric interaction between μ-mesons and nucleons.