Breit Interaction and DoubleKVacancies in Nuclear Transitions

Abstract
It is shown that the energy shift of K x rays emitted by an atom doubly ionized in the K shell comprises a 16% Breit-interaction contribution for Z=81 and thus constitutes a sensitive test of these corrections. The calculated shift of the Kα1 line agrees with the present experiment (1160 ± 70 e V). This invalidates the much larger 2100-e V shift, reported by another group, which appears to be due to spurious effects.