Isotopic spin selection rules XIV: Transitions between mirror states in 13C and 13N

The 3.68 mev 3/2 - state of 13 C is shown, by a coincidence technique to cascade via the 3.09 mev 1/2+ state with a probability of (6−5±1.0) × 10 −3 . The rule that Corresponding E1 transitions in mirror nuclei have the same reduced speed, i.e. are mirror transitions, is used to deduce the speed of this weak branch from data available in 13 N and hence to determine the radiative width of the M1 transition to ground from the 3.68 mev state. This is (0.40-0.75) ev. The speed of this transition, which is not a mirror transition to the corresponding one in 13 N, is compared with the prediction of the independent particle model. Agreement is obtained within the range of the intermediate coupling parameter a/K that satisfies other data in the A =13 system.