Magnetic field control of elastic scattering in a cold gas of fermionic   lithium atoms
  We study elastic collisions in an optically trapped spin mixture of fermionic lithium atoms in the presence of magnetic fields up to 1.5kG by measuring evaporative loss. Our experiments confirm the expected magnetic tunability of the scattering length by showing the main features of elastic scattering according to recent calculations. We measure the zero crossing of the scattering length that is associated with a predicted Feshbach resonance at 530(3)G. Beyond the resonance we observe the expected large cross section in the triplet scattering regime. 
S. Jochim, M. Bartenstein, G. Hendl, J. Hecker Denschlag, R. Grimm, A.   Mosk, M. Weidem\"uller