In this study the decay of Erg+m149 by positron emission, electron capture, and β-delayed proton emission was investigated. Gamma rays associated with Erm149 decay were placed in a decay scheme on the basis of γγ and xγ coincidences and half-life. We assigned 120 γ rays deexciting 91 levels in Ho149 to 8.9±0.2 s Erm149 decay. The πs1/2 single-particle state in Ho149 was observed to occur at 49.0 keV above the πh11/2 ground state. A (3.5±0.7) % isomeric transition decay branch and a (0.18±0.07) % β-delayed proton decay branch were determined for Erm149 decay. Three additional γ rays were assigned to 4±2 s Erg149 decay and a (7±2) % β-delayed proton decay branch was determined. Measured EC/β+ ratios to proton emitting states in Ho149 resulted in a (QEC-Sp)=7.0-0.4+5.0 MeV for ER8149 decay and a Sp=1.4-0.6+10 MeV for Ho. The β-delayed proton spectrum from Erg149 consisted of a highly structured component corresponding to the deexcitation of levels between 4 and 5 MeV in Ho149 and a structureless component corresponding to decay from higher levels. The β-strength function for Erg+m149 decay is discussed in terms of single-particle shell-model structure, weak coupling to the Dy148 core, and decay of πh11/2 protons across the shell closure to the νh9/2 neutron orbital.
ASJC Scopus subject areas
- Nuclear and High Energy Physics