The effect of the Coulomb interaction of the ejected β ray with the residual atomic electron is derived in a most general form for the β decay of a tritium atom. Corrections are calculated to first order, and transition probabilities to excited states of helium are shown to be modified by at most 0.02% from the usual sudden approximation. Detailed comparison is made with the work of Williams and Koonin who neglected the difference between atomic energy levels.

• Received 18 February 1986

DOI:https://doi.org/10.1103/PhysRevC.34.336