After the decay of the above-described series, a second group of alpha-particle emitters can be resolved. This second series, which decays with the 00-hour half-life of its protactinium parent, is a collateral branch of the 0n radioactive family as follows: $_{00}$Pa$^{000}\stackrel{\alpha}{\longrightarrow}_{00}$Ac$^{000}\stackrel{\alpha}{\longrightarrow}_{00}$Fr$^{000}\stackrel{\alpha}{\longrightarrow}_{00}$At$^{000}\stackrel{\alpha}{\longrightarrow}$..." The 