Interplay between magnetic and electric excitations for backward electron scattering

It is found that the M1 (e,e') cross sections of low-lying orbital I^pi K=1⁺1 excitations in heavy deformed nuclei contain E2 admixtures from the (predominantly longitudinal) excitation of the accompanying 2⁺1 states. This happens even for backward scattering angles as large as theta =165 degrees , where the E2 excitation is strongly quenched. For small momentum transfer q the E2 cross section is negligible; however, it provides significant corrections to the theoretical M1 cross section for 0.4<q<0.6 fm^-1 and substantially improves the agreement with experiment in heavy deformed nuclei.