Low-energy magnetic dipole response in 56Fe from high-resolution electron scattering Original Research Article

The 56Fe(e, e′) reaction has been studied for excitation energies up to about 8 MeV and momentum transfers q≃0.4–0.55 fm−1 at the Darmstadt electron linear accelerator (DALINAC) with kinematics emphasizing M1 transitions. Additional data have been taken for q≃0.8–1.7 fm−1 at the electron accelerator NIKHEF, Amsterdam. A PWBA analysis allows spin and parity determination of the excited states. For M1 excitations, transition strengths are derived with a DWBA analysis using shell-model form factors. The resulting B(M1) strength distribution is compared to shell-model calculations employing different effective interactions. The form factor of the prominent low-lying M1 transition at 3.449 MeV demonstrates its dominant orbital nature. It represents a major part of the scissors mode in 56Fe.