Nuclear Levels ofDy162

Abstract

The nuclear level scheme of ${\mathrm{Dy}}^{162}$ has been studied utilizing a variety of experimental methods. From the reaction ${\mathrm{Dy}}^{161}(n, \gamma ){\mathrm{Dy}}^{162}$, low-energy $\gamma$-ray transitions were measured between 40 and ≈1350 keV with a bent-crystal spectrometer, and the ($n, e^{-}$) conversion-electron spectrum was investigated in the energy range between 160 and 1300 keV with a double-focusing $\beta$ spectrometer. Altogether, some 160 transitions were found, and multipolarities were assigned for about 50 of these. High-energy $\gamma$ rays from neutron capture in ${\mathrm{Dy}}^{161}$ were measured in the energy region between 4.9 and 8.2 MeV with a Ge(Li) detector operated in the pair mode; 49 transitions were found. Furthermore, the reactions ${\mathrm{Dy}}^{162}(p, p^{\prime })$, ${\mathrm{Dy}}^{162}(d, d^{\prime })$, ${\mathrm{Dy}}^{161}(d, p)$, and ${\mathrm{Dy}}^{163}(d, t)$ have been studied at 12-MeV beam energy, using a broad-range magnetic spectrograph. Combining the results of all these experiments, a level scheme containing 90% of the intensity of the low-energy ($n, \gamma$) spectrum of ${\mathrm{Dy}}^{162}$ was constructed consisting of the following levels: the ground-state rotational band up to the $8^{+}$ level; the $K=2^{+}$ ($\gamma$-vibrational) band at 888.22 keV including all members up to the possible $7^{+}$ state; the $K=2^{-}$ octupole-vibrational or [411↑-523↑] band with the band head at 1148.29 keV and including members up to the tentative $5^{-}$ and $6^{-}$ levels; the $K=4^{+}$ [521↑+523↓] band at 1535.89 keV containing members up to the $6^{+}$ and possibly the $7^{+}$ level; a $K=0^{-}$ band (probably octupole) with $1^{-}$ and $3^{-}$ members at 1275.4 and 1357.0 keV, and possibly the $5^{-}$ member at 1520 keV; a tentative $K=0^{+}$ band with $2^{+}$ and $4^{+}$ members at 1206.1 and 1390.3 keV, suggesting the $0^{+}$ level at 1127 keV; the $K=1^{+}$ [521↑-523↓] band at 1745 keV containing states up to the $6^{+}$ level; the $K=3^{-}$ [642↑+521↓] band at 1770 keV containing levels up to the $6^{-}$ member; and finally the $K=2^{-}$ [642↑-521↓] band at 1866 keV containing levels up to the $5^{-}$ state. Other unassigned levels were found above 1.4 MeV in the ($d, p$), ($d, t$), and high-energy ($n, \gamma$) measurements. The agreement between experimental and calculated cross sections for the ($d, t$) and ($d, p$) reactions was found to be good for the [521↑±523↓] and the [642↑±521↓] states, but not so good for the [642↑±523↓] states. The neutron binding energy in ${\mathrm{Dy}}^{162}$ was determined as 8192.8±3 keV.