Shape of the Beta-Ray Distribution Curve of Radium E at High Energies

Abstract

The beta-ray spectrum of radium E was measured by means of a magnetic spectrometer and coincident counters with special emphasis on the shape of the curve in the neighborhood of the end-point. Because of the strong source available, and the low background of the detecting mechanism, it was possible to obtain significant data much closer to the end-point than has been done heretofore. The distribution was found to end, without a tail, at $H\rho =5330\mathrm{}$ oersted-cm, or 1.17×${10}^6$ electron volts. The Fermi and K-U plots of the experimental data do not give straight lines as predicted by the theory. Extrapolation of the straight part of the K-U plot gives an end-point 17 percent higher than that observed.