  Ultracold molecules are associated from an atomic Bose-Einstein condensate by
ramping a magnetic field across a Feshbach resonance. The reverse ramp
dissociates the molecules. The kinetic energy released in the dissociation
process is used to measure the widths of 4 Feshbach resonances in 87Rb. This
method to determine the width works remarkably well for narrow resonances even
in the presence of significant magnetic-field noise. In addition, a
quasi-mono-energetic atomic wave is created by jumping the magnetic field
across the Feshbach resonance.
