Abstract
Making use of the predictions of "alpha-systematics" on the extent of alpha-branching of the isotope AcK and of the properties of the resultant daughter, the branching was looked for and found in the francium fraction isolated from a 20-mC source of . The observed branching rate is 4×, and the daughter decays predominately by the emission of 6.27-Mev alpha-particles with a half-life of 0.9 minute to the new isotope , which in turn emits particles with a half-life of 8 minutes. also decays by emission to about once in 30 disintegrations. It is pointed out that this is the first reported instance of a chemical identification of an isotope of element 85 from a natural source, although other shorter-lived astatine isotopes are known to exist.
- Received 17 December 1952
DOI:https://doi.org/10.1103/PhysRev.90.267
©1953 American Physical Society