Coulomb-nuclear interference with alpha particles in the excitation of the 2(+)1 states in 100,102,104Ru.

Abstract

Coulomb-nuclear interference data for incident energies between 9 and 17 MeV were obtained in the form of elastic and inelastic (to the ${2}_{1}^{+}$ states) excitation functions of backscattered (\ensuremath{\theta}\ensuremath{\simeq}172.8\ifmmode^\circ\else\textdegree\fi{}) alpha particles on $^{100,102,104}\mathrm{Ru}$. The analysis was done in a distorted-wave Born approximation within a deformed optical model approach. B(E2) values, obtained from the charge deformation lengths ${\mathrm{\ensuremath{\delta}}}^{\mathit{C}}$ extracted from the low energy data, are compatible for the three isotopes within \ensuremath{\sim} 2\ensuremath{\sigma} with published values. The nuclear quadrupolar deformation lengths ${\mathrm{\ensuremath{\delta}}}^{\mathit{N}}$, obtained from the analysis of the interference region of the excitation functions, and also of one angular distribution at 22 MeV measured for $^{100}\mathrm{Ru}$ are generally lower than the corresponding charge deformation lengths, the difference increasing with increasing A of the isotope, ${\mathrm{\ensuremath{\delta}}}^{\mathit{N}}$ being 18% lower than ${\mathrm{\ensuremath{\delta}}}^{\mathit{C}}$ for $^{104}\mathrm{Ru}$ (${2}_{1}^{+}$). Nuclear deformation lengths associated with the ${3}_{1}^{\mathrm{\ensuremath{-}}}$ states of $^{100,102,104}\mathrm{Ru}$ and with the ${4}_{2}^{+}$ state of $^{100}\mathrm{Ru}$ at 2.367 MeV were also obtained as a by-product of the present work. \textcopyright{} 1996 The American Physical Society.