Electron scattering off 65Cu and 71Ga

Abstract

Electron scattering on the fp-shell nuclei 65Cu and 71Ga has been investigated. Measurements have been performed up to a momentum transfer of 2.7 fm −1 at forward and at backward scattering angles in order to separate the transverse and longitudinal form factors of the low-lying excited states. This allowed the extraction of the transition densities and probabilities, which are compared to particle-core coupling calculations: particle-vibration coupling model (PVCM) and quasiparticle-cluster vibration model (QCVM). These models appear to be more applicable to 65Cu than to 71Ga. Reasons for this are discussed. In general the transition charge densities confirm the distinction between quasiparticle states and collective excitations, that one expects already on the basis of spectroscopic factors. The relative importance of quasiparticle and phonon contributions to the transitions is reflected in the specific shapes of the transition densities for each level. Transition current densities are often less well predicted than charge densities and are quite sensitive to the model used.