Nuclear Levels ofLu175

Abstract

The negatron decay of ${\mathrm{Yb}}^{175}$ (4.2 day) and orbital electron capture decay of ${\mathrm{Hf}}^{175}$ (70 day) to ${\mathrm{Lu}}^{175}$ have been investigated in detail using a magnetic lens spectrometer, 180\ifmmode^\circ\else\textdegree\fi{} permanent magnet spectrographs, scintillation spectrometers, and coincidence techniques. Eleven gamma transitions in ${\mathrm{Lu}}^{175}$ of the following energies and indicated multipolarities have been observed: 89.3 ($M1+E2$), 113.6 ($M1+E2$), 137.6, 144,229.3 ($E2$), 251, 282.4 ($E1+M2$), 318.6, 342.9 ($M1+E2$), 396.0 ($E1+M2$), and 432.2 kev. On the basis of these measurements, consistent decay schemes for ${\mathrm{Yb}}^{175}$ and ${\mathrm{Hf}}^{175}$ are proposed. Observed nuclear levels in ${\mathrm{Lu}}^{175}$ excited by the radioactive decay of these two nuclides occur at 113.6, 251.2, 342.9, 396.0, and 432.2 kev and are assigned spin and parity values $\frac{9}{2}+$, $\frac{11}{2}+$, $\frac{5}{2}+$, $\frac{9}{2}\ensuremath{-}$, and $\frac{5}{2}+$, respectively. The levels at 113.6 kev and 251.2 kev constitute a rotational band whose base state occurs at stable ${\mathrm{Lu}}^{175}(\frac{7}{2}+)$.