Abstract
A new isotope of the element emanation has been identified among the spallation products of thorium bombarded with 110-Mev protons. This isotope, , decays with a half-life of 25 minutes. The decay goes 80 percent by beta emission to identified by its characteristic alpha particle groups and by the observance of the alpha particles of the decay products, and . In 20 percent of its disintegrations emits an alpha particle of 6.0-Mev energy unresolved from the 6.0-Mev alpha particle of , and gives rise to , a previously unreported isotope of polonium. has a half-life of less than 10 seconds and emits alpha particles of 6.54±0.02 Mev.
An attempt was made to isolate from a sample of where it should be found as a result of slight alpha branching of . The experiment was negative and a lower limit of 500 years was placed on the partial alpha half-life of .
- Received 29 August 1955
DOI:https://doi.org/10.1103/PhysRev.101.136
©1956 American Physical Society