Level Structure inEu145

Abstract

Levels in ${}_{}{}^{145}{}_{}{}^{}\mathrm{Eu}$ were investigated by the ${}_{}{}^{144}{}_{}{}^{}\mathrm{Sm}({}_{}{}^3{}_{}{}^{}\mathrm{He}, d)$ reaction and by the decay of 25-min ${}_{}{}^{145}{}_{}{}^{}\mathrm{Gd}$. At the ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ energy used, i.e., 40.33 MeV, the angular distributions for the stripping reaction were found to be highly structured. This fact permitted reliable assignments of transferred orbital angular momenta to the residual levels. Singles $\gamma$-ray spectra for the decay of ${}_{}{}^{145}{}_{}{}^{}\mathrm{Gd}$ were measured with a 20-${\mathrm{cm}}^3$ Ge(Li) detector. The two sets of experimental data were then used to propose the following sequence of ${}_{}{}^{145}{}_{}{}^{}\mathrm{Eu}$ levels: 0 (${\frac{5}{2}}^{+}$), 330.1 (${\frac{7}{2}}^{+}$), 716 (${}_{}{}^{-}{}_{}{}^{}\frac{11}{2}$), 808.4 (${\mathrm{½}}^{+}$), 1041.9 (${\frac{3}{2}}^{+}$), 1599.9 (${\frac{7}{2}}^{+}$), 1757.9 (${\frac{3}{2}}^{+}$), 1844.7 ($\frac{3}{2}, {\frac{5}{2}}^{+}$), 1880.6 (½, ${\frac{3}{2}}^{+}$), 2112.0 ($\frac{3}{2}, {\frac{5}{2}}^{+}$), and a (${\mathrm{½}}^{+}$), ($\frac{3}{2}, {\frac{5}{2}}^{+}$) doublet at ∼ 2480 keV. The salient features of this level scheme are that (1) the (${}_{}{}^3{}_{}{}^{}\mathrm{He}$, $d$) reaction predominantly populates the first five energy levels, and (2) the decay from ${}_{}{}^{145}{}_{}{}^{}\mathrm{Gd}$...