Excitation of positive-parity states in electron scattering fromZr90

Electron scattering cross sections for ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$ have been measured with a resolution of less than 40 keV in a momentum transfer range between $0.4<q<\mathrm{}3.1\mathrm{}$ ${\mathrm{fm}}^{-1\mathrm{}}$ both at forward angles and at 160°, which allows a separation of longitudinal and transverse form factors. The analysis of the positive-parity states (including previous data for some of the states) results in transition densities. Most densities are compared to various model calculations. The density of the $8^{+}$ level is used to determine the radius of the $g_{\frac{9}{2}}$ proton orbit as $R \left(g_{\frac{9}{2}}\right)=5.035\mathrm{}\pm 0.045$ fm.