Nuclear Levels ofDy162

Abstract

The nuclear level scheme of ${\mathrm{Dy}}^{162}$ has been studied utilizing a variety of experimental methods. From the reaction ${\mathrm{Dy}}^{161}(n, \ensuremath{\gamma}){\mathrm{Dy}}^{162}$, low-energy $\ensuremath{\gamma}$-ray transitions were measured between 40 and \ensuremath{\approx}1350 keV with a bent-crystal spectrometer, and the ($n, {e}^{\ensuremath{-}}$) conversion-electron spectrum was investigated in the energy range between 160 and 1300 keV with a double-focusing $\ensuremath{\beta}$ spectrometer. Altogether, some 160 transitions were found, and multipolarities were assigned for about 50 of these. High-energy $\ensuremath{\gamma}$ 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 ${\mathrm{Dy}}^{162}(p, {p}^{\ensuremath{'}})$, ${\mathrm{Dy}}^{162}(d, {d}^{\ensuremath{'}})$, ${\mathrm{Dy}}^{161}(d, p)$, 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 ($n, \ensuremath{\gamma}$) spectrum of ${\mathrm{Dy}}^{162}$ was constructed consisting of the following levels: the ground-state rotational band up to the ${8}^{+}$ level; the $K={2}^{+}$ ($\ensuremath{\gamma}$-vibrational) band at 888.22 keV including all members up to the possible ${7}^{+}$ state; the $K={2}^{\ensuremath{-}}$ octupole-vibrational or [411\ensuremath{\uparrow}-523\ensuremath{\uparrow}] band with the band head at 1148.29 keV and including members up to the tentative ${5}^{\ensuremath{-}}$ and ${6}^{\ensuremath{-}}$ levels; the $K={4}^{+}$ [521\ensuremath{\uparrow}+523\ensuremath{\downarrow}] band at 1535.89 keV containing members up to the ${6}^{+}$ and possibly the ${7}^{+}$ level; a $K={0}^{\ensuremath{-}}$ band (probably octupole) with ${1}^{\ensuremath{-}}$ and ${3}^{\ensuremath{-}}$ members at 1275.4 and 1357.0 keV, and possibly the ${5}^{\ensuremath{-}}$ 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\ensuremath{\uparrow}-523\ensuremath{\downarrow}] band at 1745 keV containing states up to the ${6}^{+}$ level; the $K={3}^{\ensuremath{-}}$ [642\ensuremath{\uparrow}+521\ensuremath{\downarrow}] band at 1770 keV containing levels up to the ${6}^{\ensuremath{-}}$ member; and finally the $K={2}^{\ensuremath{-}}$ [642\ensuremath{\uparrow}-521\ensuremath{\downarrow}] band at 1866 keV containing levels up to the ${5}^{\ensuremath{-}}$ state. Other unassigned levels were found above 1.4 MeV in the ($d, p$), ($d, t$), and high-energy ($n, \ensuremath{\gamma}$) 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\ensuremath{\uparrow}\ifmmode\pm\else\textpm\fi{}523\ensuremath{\downarrow}] and the [642\ensuremath{\uparrow}\ifmmode\pm\else\textpm\fi{}521\ensuremath{\downarrow}] states, but not so good for the [642\ensuremath{\uparrow}\ifmmode\pm\else\textpm\fi{}523\ensuremath{\downarrow}] states. The neutron binding energy in ${\mathrm{Dy}}^{162}$ was determined as 8192.8\ifmmode\pm\else\textpm\fi{}3 keV.