1. National Research Council, Canadian Neutron Beam Centre, Chalk River, Ontario K0J 1J0, Canada, Guelph-Waterloo Physics Institute and Biophysics Interdepartmental Group, University of Guelph, Guelph, Ontario N1G 2W1, Canda, Department of Physics, University of Guelph, Guelph, Ontario N1G 2W1, Canada, and Department of Physics, Indiana University−Purdue University Indianapolis, Indianapolis, Indiana 46202-3273