Decrease in the probability of tritium decay in an external electric field

The probability of tritium beta decay is shown to decrease under the effect of a constant uniform external electric field on the atom. For the tritium atom, the effect is due first to the reduction of the beta-decay endpoint energy and second to the reduction of the density of vacant bound electron states at the nucleus. Both of these factors reduce the beta-decay probability: the first reduces the probability of decay to continuum electron states, while the second reduces the probability of decay to a bound state.