Electric giant resonances in 40Ca and 48Ca probed with electron and proton scattering coincidence experiments

Abstract

Excitation and particle decay of electric giant resonances in 40Ca and 48Ca are studied with electron and proton beams. Recent results of a 48Ca(e,e′n) measurement performed at the S-DALINAC in Darmstadt with kinematics that selectively populate electric monopole, dipole and quadrupole excitations are presented. The extracted B(E1) strength distribution is in good agreement with photo nuclear data and the predictions of microscopic calculations. The summed B(E2+E0) strength distribution, however disagrees with the result of these calculations. The neutron emission of the giant dipole resonance in 48Ca shows a large fraction of direct decay to 47Ca hole states. In addition, isoscalar giant monopole resonance strength in 40Ca was extracted from (e,e′α 0) and (e,e′α 1) angular correlations. A study of the quadrupole strength in the α 0 decay channel of 40Ca with a (p,p′α) coincidence measurement reiterates the unsolved discrepancy between results from electromagnetic and hadronic probes.