DECAY OF THE HIGH-SPIN ISOMERS IN HO-150,HO-151,HO-152

The electron-capture decay properties of the high-spin isomers in Ho150,151,152 were investigated. The nuclides were produced in B10 bombardments of samarium and then transported to shielded areas with the use of gasjet systems. Singles and coincidence γ-ray measurements were made. Each isomer decays primarily to one excited state in its dysprosium daughter by means of an allowed β transition (logft values are ∼4.5). The following explanations are proposed. For Ho150 and Ho152 the transitions connect 9+(πh112,νf72) levels with 8+(νh92,νf72) levels in Dy150(2401.8 keV) and Dy152(2437.6 keV). Deexcitation to the ground states then follows via a cascade of four E 2 γ rays. In Ho151 the β transition represents the changeover of an h112 proton orbital to an h92 neutron orbital in Dy151. This single neutron state lies at 527.4 keV and deexcites directly to the ground state. The α decay of Ho152 was also investigated with the use of an on-line isotope separator. Its α-decay branching ratio was determined to be 10.5±3.0%. RADIOACTIVITY Ho150, Ho151, Ho152; measured T12, Eγ, Iγ, γγ coin; Dy150, Dy151, Dy152 deduced levels, Jπ. Ho152; measured Iγ, Iα, deduced α-decay branching ratio: mass separation. © 1979 The American Physical Society.