Both external and internal bremsstrahlung produced in the β decay of tritium and of tritium-rare gas mixtures have been investigated. The ratio of external to internal bremsstrahlung varied for the different sources by more than two orders of magnitude. From an analysis of the shape of the x-ray spectrum, the maximum kinetic energy of electrons emitted in the β decay of tritium molecules has been determined to be 18 556(6) eV.

• Received 31 January 1992

DOI:https://doi.org/10.1103/PhysRevC.46.1267