Excitation and decay of giant resonances in theCa40(e,ex) reaction

Abstract
The Ca40(e,ex) reaction has been investigated for excitation energies between 8 and 26 MeV and momentum transfers from 0.25 to 0.66 fm1 at the continuous-wave electron accelerators MAMI at Mainz S-DALINAC at Darmstadt. A multipole decomposition of the cross sections reveals strongly fragmented E2 (plus E0) strength around 14 and 17 MeV in contrast to all theoretical predictions. Angular correlations of proton decay are described over the entire energy range by a continuum random-phase-approximation approach. A comparison of the branching ratios to statistical model calculations provides information on the dominant damping mechanism.