Observation of elastic collisions between lithium atoms and calcium ions

We observed elastic collisions between laser-cooled fermionic lithium atoms and calcium ions at the energy range from 100 mK to 3 K. Lithium atoms in an optical-dipole trap were transported to the center of the ion trap using an optical-tweezer technique, and a spatial overlap of the atoms and ions was realized in order to observe the atom-ion interactions. The elastic-scattering rate was determined from the decay of atoms due to elastic collisions with ions. The collision-energy dependence of the elastic-scattering cross section was consistent with semiclassical collision theory.