Levels inCe148from the decay of mass separatedLa148

Abstract

The level scheme of $^{148}\mathrm{Ce}$ populated by $\ensuremath{\beta}$ decay of $^{148}\mathrm{La}$, produced in thermal neutron fission of $^{235}\mathrm{U}$, has been studied. Ion beams of mass 148 were separated by an on-line isotope separator and deposited on a movable tape. Gamma-ray singles, $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ time, $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ angular correlations, and time sequenced $\ensuremath{\gamma}$ and $\ensuremath{\beta}$ spectra were collected. The half-life for $^{148}\mathrm{La}$ was measured to be 1.05\ifmmode\pm\else\textpm\fi{}0.01 s. A level scheme for $^{148}\mathrm{Ce}$ is presented including several members of the ground, $\ensuremath{\beta}$, $\ensuremath{\gamma}$, and octupole bands. The resulting level scheme has been compared with other $N=90$ nuclides and with interacting-boson-approximation-2 calculations.RADIOACTIVITY $^{148}\mathrm{La}$ [from $^{235}\mathrm{U}({n}_{\mathrm{th}}, f)$] measured ${t}_{\frac{1}{2}}$, ${E}_{\ensuremath{\gamma}}$, ${I}_{\ensuremath{\gamma}}$, $\ensuremath{\gamma}\ensuremath{\gamma}t$ coincidence, $\ensuremath{\gamma}\ensuremath{\gamma}(\ensuremath{\theta})$ angular correlation; HPGe and Ge(Li) detectors; $^{148}\mathrm{Ce}$ deduced levels, ${J}^{\ensuremath{\pi}}$ and ${I}_{\ensuremath{\beta}}$. Mass-separated $^{148}\mathrm{Ba}$ activity. IBA-2 calculations: ${E}_{\mathrm{level}}$ and $B(E2)$.