Saturation ofB(E2) andB(M1) strengths in actinide nuclei

The saturation of the B(E2,$0_1^{+}$→$2_1^{+}$) strengths in the actinide nuclei is described very well by an analytical formula using shell closures at Z=82,126 and N=126,184. The transition towards saturation is much more gradual than in the rare earth nuclei and reaches a saturation value of 325±10 W.u. By assuming a similar correlation between B(E2) and summed B(M1) strengths as observed in the rare-earth region we predict for actinide nuclei a saturation of the summed B(M1,$0_1^{+}$→$1^{+}$) strengths below about 3 MeV of 3.7±0.4 ${\mathrm{\mu }}_{\mathit{N}}^2$. We compare our estimates for (${\mathit{g}}_{\mathrm{\pi }}$-${\mathit{g}}_{\nu }$ ${)}^2$ with values obtained from extrapolations of averaged regional boson g factors.