1. Department of Physics, Brock University, St. Catharines, Ontario L2S 3A1, Canada, Canadian Neutron Beam Centre, National Research Council, Chalk River, Ontario K0J 1J0, Canada, Guelph-Waterloo Physics Institute and Biophysics Interdepartmental Group, University of Guelph, Guelph, Ontario N1G 2W1, Canada, and Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana 46202-3273