Removing a Ray from a Noncompact Symplectic Manifold

We prove that any noncompact symplectic manifold that admits a properly embedded ray with a wide neighborhood is symplectomorphic to the complement of the ray by constructing an explicit symplectomorphism in the case of the standard Euclidean space. This allows us to excide a ray from a symplectic manifold and we use this excision trick to find a nowhere vanishing Liouville vector field on every cotangent bundle.