Observation of Long-Lived NeutralVParticles

detection instruments is exponential for all beta-radioactive isotopes in which single spectra are involved, i.e., a single 6nal state and a single original state —this is so even though the transition may be highly forbidden as in the case of K".Table I gives data for typical betaradioactive isotopes of varying characteristics for various absorbers. It has been discovered that there is a particularly simple relation between the half-thickness in aluminum and the upper energy limit, E, of the beta spectrum involved. This relation is shown graphically in Fig. 1 and is given by the following equation: