Decay of Europium-154

The gamma rays and electrons of fission-product europium (${\mathrm{Eu}}^{153}$, ${\mathrm{Eu}}^{154}$, and ${\mathrm{Eu}}^{155}$) have been studied, and the results obtained for ${\mathrm{Eu}}^{154}$ are presented. Gamma rays belonging to this isotope have been identified at 0.1229 Mev (35%), 0.2480 Mev, ${0.593}_3$ Mev (4%), ${0.694}_1$ Mev (≤3.5%), ${0.705}_8$ Mev (≤3.5%), ${0.724}_9$ Mev (21%), ${0.758}_9$ Mev (≤3.5%), ${0.875}_3$ Mev (13%), ${0.998}_2$ Mev (14%), 1.007 Mev (17%), 1.277 Mev (42%), and ∼1.6 Mev (∼3%). Beta end points of ${\mathrm{Eu}}^{154}$ were measured at 1.85, 0.87, 0.59, and 0.25 Mev. Multipolarities for most of the above gamma-ray transitions have been suggested on the basis of the measured $K$-shell conversion coefficients. The decay scheme of ${\mathrm{Eu}}^{154}$ has been deduced, and, in most respects, the resulting levels of ${\mathrm{Gd}}^{154}$ conform well with the Bohr-Mottelson unified nuclear model and with other even-even nuclei in the strong-coupling regions.