| Popis: |
The radiations associated with the decay of 11.4-min $^{152}\mathrm{Nd}$ and its 4.1-min $^{152}\mathrm{Pm}$ daughter have been studied with Ge(Li), NaI(Tl), and anthracene detectors in both singles and coincidence configurations. A tentative decay scheme for $^{152}\mathrm{Nd}$ involving allowed $\ensuremath{\beta}$ decay to the 4.1-min isomer of $^{152}\mathrm{Pm}$ (${1}^{+}$) ($logft=4.8$) and to an excited ${1}^{+}$ level 294.6-keV higher ($logft=4.2$) is presented. The 4.1-min level undergoes $\ensuremath{\beta}$ decay to 10 levels in $^{152}\mathrm{Sm}$ which have been previously established in decay studies of $^{152}\mathrm{Eu}$, and from Coulomb excitation and reaction studies. A new level in $^{152}\mathrm{Sm}$ has been placed at \ensuremath{\cong}1081 keV. The total $\ensuremath{\beta}$-decay energy is nearly the same as the measured $\ensuremath{\beta}$ end-point energy, 3.6 \ifmmode\pm\else\textpm\fi{} 0.2 MeV.Evidence is presented for the existence of two previously unreported high-spin isomers of $^{152}\mathrm{Pm}$ having half-lives of 7.5 \ifmmode\pm\else\textpm\fi{} 1.0 min and \ensuremath{\cong}18 min. A decay scheme is proposed for the 7.5-min isomer (${4}^{\ifmmode\pm\else\textpm\fi{}}$) of $^{152}\mathrm{Pm}$ including 16 known $^{152}\mathrm{Sm}$ levels and new levels at 1081, 1804, and possibly 1941 keV. At least 40% of the $\ensuremath{\beta}$ transitions decay to the 1804-keV level with a $log\mathrm{ft}$ of \ensuremath{\cong}5.7 which suggests hindered allowed or first-forbidden decay. The observation of a 1.8-MeV $\ensuremath{\beta}$ group in coincidence with an intense 1437-keV $\ensuremath{\gamma}$ transition which deexcites the 1804-keV level establishes the total $\ensuremath{\beta}$-decay energy for 7.5-min $^{152}\mathrm{Pm}$ as 3.6 \ifmmode\pm\else\textpm\fi{} 0.1 MeV. The \ensuremath{\cong}18-min isomer (\ensuremath{\ge}${6}^{\ifmmode\pm\else\textpm\fi{}}$) of $^{152}\mathrm{Pm}$ appears to populate a new level at 2172 keV and possibly the 1941-keV level in $^{152}\mathrm{Sm}$. |
