Study of the giant multipole resonance decay in 90Zr by means of particle angular correlation measurements

In the present thesis the decay of the isoscalar electric giant multipole resonances in 90Zr was studied by means of a coincidence experiment at the energy-resolved α beam of the Karlsruhe isochronous cyclotron. Thereby after excitation by inelastic alpha scattering the neutron decay of the giant resonance region was observed directly by an α,n-coincidence measurement. The aim of this experiment was to determine the relative branching ratios of the neutron decay from the giant E2-resonance region into the low-lying states in the nucleus 89Zr model-independently. For this the decay neutrons were detected under certain polar angles, and by this an averaging over the angular correlation function was reached. Additionally a study of the neutron decay from the region of the giant monopole resonance followed in order to obtain informations about the presence of a direct decay component. The scattered α particles were detected in a maximum and a minimum of the E2-angular distribution in order to meet further statements about the giant resonance. From the cross section analysis in connection with the results from the determined branching ratios in the giant resonance region sum rule values for the E2-strength of about 40% and about 4% for the E4-strength can be estimated. (orig./HSI)