Descrição: A systematic analysis of $\alpha$-decay half-lives of radioactive lanthanide isotopes, $T^{\alpha}_{1/2}$, has been developed which allows one to obtain an accurate and reliable $T^{\alpha}_{1/2}$-value of ($103.4\pm 5.3$) Ma for the extinct $^{146}$Sm isotope, and to predict a $T^{\alpha}_{1/2}$-value of $(1.8\pm 0.2)\times 10^{18}$~a for the yet unknown alpha radioactivity of $^{149}$Sm isotope.

Número: CBPF-NF-005/26