Shell effects for isovector l-forbidden M1 transitions in odd nuclei

It is inferred from the analysis of the experimental data that the reduced probabilities of isovector l -forbidden M 1 transitions achieve maximum values in nuclei with a magic core. The minimum values are related to γ transitions in nuclei belonging to the region of stable deformation with A ≈ 25. Isovector l -forbidden M 1 transitions in mirror nuclei are explored. The ratio of the reduced probabilities for proton and neutron transitions shows the maximum deviation from the theoretical evaluations for the pair of nuclei 41 Ca- 41 Sc consisting of the even-even magic core 40 Ca and one nucleon outside the closed 1 d 2 s shell.