Single-particle properties of 51V and 90Zr studied with the (e,e'p) reaction

Abstract

Proton spectral functions for the reactions 51V(e, e'p) and 90Zr(e, e'p) have been obtained with the coincidence setup at NIKHEF-K. The coincidence cross sections up to 21 MeV excitation energy were measured in the missing momentum range −40 < Pm < 280 MeV/c with an absolute precision of 4%. The achieved 130 keV energy resolution allowed to deduce momentum distributions ρ(Pm) for transitions to many discrete final states. A CDWIA analysis of the measured ρ(Pm) yielded rms radii of the single-particle orbitals and spectroscopic factors for the various transitions. The uncertainties in the analysis due to the treatment of the final-state interaction could be reduced by a combined analysis of the present data and elastic proton-scattering data in the same mass and energy region. The extracted spectroscopic factors are compared to those deduced from the (d3, He) reaction. The strength in the continuum (up to Ex = 21 MeV) has been decomposed into various orbital components by using the dependence of ρnlj(Pm) on the values of n and l. Whereas in general the orbit radii and the binding energies are in fair agreement with the results of mean-field calculations, the total spectroscopic strength for valence orbits is only 40–60% of the single-particle sum-rule estimate. For deep-hole states we find 60–80%. These values are about 15% smaller than the predictions of recent mean-field calculations that include correlations. Possible origins of this difference are discussed.