title: Low-Energy Magnetic Dipole Radiation in Open-Shell Nuclei.
abstract: Low-energy M1 strength functions of ^{60,64,68}Fe are determined on the basis of large-scale shell-model calculations with the goal to study their development from the bottom to the middle of the neutron shell. We find that the zero-energy spike, which characterizes nuclei near closed shells, develops toward the middle of the shell into a bimodal structure composed of a weaker zero-energy spike and a scissorslike resonance around 3 MeV, where the summed strengths of the two structures change within only 8% around a value of 9.8  μ_{N}^{2}. The summed strength of the scissors region exceeds the total γ absorption strength from the ground state by a factor of about three, which explains the discrepancy between total strengths of the scissors resonance derived from (γ, γ^{'}) experiments and from experiments using light-ion induced reactions.
authors.affiliation: Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Schwengner
authors.affiliation: Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556, USA.
authors.forename: S
authors.initials: S
authors.lastname: Frauendorf
authors.affiliation: National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA.
authors.forename: B A
authors.initials: BA
authors.lastname: Brown