Survey of Inelastic Scattering of Deuterons by Heavy Elements

Abstract

Energy spectra of inelastically scattered deuterons from approximately 30 heavy elements are measured with about 80-kev resolution. Many new levels are reported, including a level in ${\mathrm{Pr}}^{141}$ whose discovery substantially alters the decay scheme of ${\mathrm{Nd}}^{141}$. The gross structure of the spectra is studied and several regularities are noted. Angular distributions in Zr and the even isotopes of Sn indicate that the parity of the strongest levels in the anomalous peaks (∼2.5 Mev) are negative, in agreement with the popular assumption that they are the $3^{-}$ collective vibrational level; however, there are also several strongly excited positive-parity levels in that region. The correlation between cross sections for exciting given levels by ($d, d^{\prime }$) and ($d, p$) or ($d, t$) reactions is studied. The correlation coefficients are generally slightly negative, but there are several cases where the same levels are strongly excited by all three reactions, including one case (in ${\mathrm{Sn}}^{117}$) where the principal $d_{\frac{5}{2}}$ single quasi-particle level is also the principal $2^{+}$ vibrational level based on the $s_{\frac{1}{2}}$ ground state. A very strong positive correlation is found between cross sections for exciting given levels by Coulomb excitation and by direct-interaction inelastic scattering. The large peaks reported by Yntema and Zeidman in inelastic deuteron scattering from Rh, Ag, and Sn at 4-5 Mev and from Ta and Pt at about 3 Mev are not found here; explanations for this are offered.