Studies of Low-Lying Levels of Even-Even Nuclei with (d, p) and (d, t) Reactions

Abstract

Low-lying states of even-even nuclei in the vibrational region were studied by exciting them with ($d, p$) and ($d, t$) reactions. The relative cross sections for exciting ground states ($G$) bear little relationship to whether they are allowed or forbidden by the simple Mayer-Jensen configurations, so that configuration mixing is generally large. Some of the details of this mixing are obtained. The allowed portion of these cross sections are generally quite close to the single-particle values. First and second excited states are much more strongly excited than expected theoretically. In ${\mathrm{Pd}}^{104}$, ${\mathrm{Pd}}^{106}$, ${\mathrm{Pt}}^{194}$, and ${\mathrm{Pt}}^{196}$ searches for the triplet in second excited states indicate that its total spacing must be less than 80 kev. New states were found in the triplet region of ${\mathrm{Cd}}^{114}$ and ${\mathrm{Cd}}^{112}$ bringing the total number of known states in these to 5 and 4, respectively; each includes two $0^{+}$ and two $2^{+}$ states. Higher excited states were studied and in almost all cases they occur below the expected position of the third member of the vibrational band; this gives evidence on the size of the energy gap. The location of all $0^{+}$ levels up to 3 Mev is determined for several nuclei. In two cases the $3^{+}$ states required by Davidov-Filipov theory are found to be $0^{+}$, and in other cases they are not found at all. A number of previously unknown levels are catalogued.