First measurement of the partial widths of ${}^{209}$Bi decay to the ground and to the first excited states

Abstract

${}^{209}$Bi alpha decay to the ground and to the first excited state have been contemporary observed for the first time with a large BGO scintillating bolometer. The half-life of ${}^{209}$Bi is determined to be $\ddot{I}{„}_{1/2}$=(2.01$\pm$0.08)$\cdot 10^{19}$ years while the branching ratio for the ground-state to ground-state transition is (98.8$\pm$0.3)%.

5 pages, 4 figures