Abstract
The beta-ray spectrum of 7.38-second has been investigated with a 180-degree magnetic spectrometer. The radioactive nuclei were produced by 1.5-Mev deuterons through the reaction , using targets of lead nitrate enriched to 64% in . Of the four known beta-ray groups, two with end-point energies 10.40±0.05 Mev and 4.39±0.07 Mev are satisfactorily resolved. The intensity of the 10.40-Mev group relative to that of the remainder of the transitions is in the ratio of 28:72, leading to . The 10.40-Mev group is shown to proceed as a first-forbidden transition, and thus the ground state of may be uniquely designated as a level.
- Received 15 November 1957
DOI:https://doi.org/10.1103/PhysRev.110.924
©1958 American Physical Society