Location of flux-induced vortex

We have obtained experimental evidence for a vortex that mediates between adjacent fluxoid states in a mesoscopic superconducting ring with nonuniform width. We have obtained information about the path of this vortex. For small fluxoid numbers the vortex crosses the sample through the narrowest part and for large fluxoid numbers through the widest part. We review our predictions for critical points. Our results are in agreement with the existent theory.