Abstract
The new nuclides, and , were identified in bombardments of . A gas-jet system was used to transport product nuclei to a shielded area suitable for -ray measurements. The 21-s isotope, , was found to decay primarily to a level at 1091 keV and less intensely to the -keV state observed in a previous in-beam -ray study. This radioactivity, in analogy to neighboring odd- terbium and holmium isotopes, probably represents the proton orbital in which decays via an allowed transition to the 1091-keV level. The latter, is therefore, proposed to be the neutron state in . The 9-s isotope, , was identified mainly through a 1688-keV -ray which: (1)was in coincidence with dysprosium x rays, (2)increased dramatically in intensity when the bombarding energy was raised from 85 to 96 MeV, and (3)remained constant (over the same range) in intensity relative to that of the 620-keV ray known to belong to decay. On the basis of systematics for low-lying levels in even-even nuclei, the 1688-keV transition is though to deexcite the first-excited state in .
RADIOACTIVITY , , measured , , , coin; , deduced levels.
- Received 19 June 1978
DOI:https://doi.org/10.1103/PhysRevC.19.482
©1979 American Physical Society