Measurement of the interaction energy near a feshbach resonance in a 6Li Fermi gas -: art. no. 020402

We investigate the strongly interacting regime in an optically trapped Li-6 Fermi mixture near a Feshbach resonance. The resonance is found at 800(40) G in good agreement with theory. Anisotropic expansion of the gas is interpreted by collisional hydrodynamics. We observe an unexpected and large shift (80 G) between the resonance peak and both the maximum of atom loss and the change of sign of the interaction energy.