ABSTRACT
Many experiments were made to determine the distribution of alpha-particles over the whole of the spectrum, which includes alpha-particles of ranges between 7 cm and 12 cm. The main difficulty in the analysis of long range groups lies in their weak intensity. The results show the presence of 12 groups. The systematic differences in energy between the present results and those given before for corresponding groups are due to the use of an incorrect extrapolated curve to obtain the velocities from the ranges. It is natural to suppose that all the observed groups of long range particles are emitted by atoms of radium C' which have been formed in an excited state by the emission of beta-particle from the parent body radium C. The velocities of the long range groups of alpha-particles from radium C' are measured with accuracy by the annular ring magnet.
