With the Wigner function moments (WFM) method the scissors mode of the actinides and rare earth nuclei are investigated. The unexplained experimental fact that in ${}^{232}\mathrm{Th}$ a double hump structure is found finds a natural explanation within WFM. It is predicted that the lower peak corresponds to an isovector spin scissors mode whereas the higher-lying states corresponds to the conventional isovector orbital scissors mode. The experimental situation is scrutinized in this respect concerning practically all results of $M1$ excitations.

• Received 31 May 2017
• Revised 22 February 2018

DOI:https://doi.org/10.1103/PhysRevC.97.044316