Gamma-Ray Anisotropies from OrientedPm144

Abstract

Radioactive ${\mathrm{Pm}}^{144}$ was oriented at low temperatures in a single crystal of neodymium ethysulfate. The gamma rays at 475, 615, and 695 kev were found to be anisotropic. The results confirm the decay scheme previously proposed as well as crystal field calculations for ${\mathrm{Pm}}^{+3\mathrm{}}$ in this lattice. It is not possible to decide between spin 5 and 6 for ${\mathrm{Pm}}^{144}$. Values were obtained for $\frac{\mathrm{}\left|A\right|\mathrm{}}{k}$ and $\left|\mu \right|$ of 0.0091°K and 1.68±0.14 nm for $I=5\mathrm{}$, or 0.0079°K and 1.75±0.14 nm for $I=6\mathrm{}$. The lowest doublet of ${\mathrm{Pm}}^{+3\mathrm{}}$ was found to be split, presumably due to Jahn-Teller distortion.