The half-life of 207Bi and decays of 211At and 211Po

The half-life of ²⁰⁷Bi was obtained from the genetic relation between ²⁰⁷Po and ²⁰⁷Bi, and between ²¹¹At and ²⁰⁷Bi. The half-life was found to be 33.4 ± 0.8 y. The half-life of ²⁰⁷Po was determined to be 5.81 ± 0.04 h by following the decay of the characteristic γ-rays from ²⁰⁷Po. The half-life of ²¹¹ At was determined tobe 7.23 ± 0.02 h by following the decay of γ-rays and α-particles from ²¹¹At and ²¹¹Po. The half-lives determined in the present work for ²⁰⁷Po and ²¹¹At agree with the literature although the half-life of ²⁰⁷Bi differs considerably from the currently accepted value of 38 y. The branching ratio of ²¹¹ At decaying through EC and α-decay modes was determined together with the branching ratios of the three α-particles emitted from ²¹¹Po.