  We have performed a fully non-perturbative calculation of the thermal
properties of a system of spin 1/2 fermions in 3D in the unitary regime. We
have determined the critical temperature for the superfluid-normal phase
transition. The thermodynamic behavior of this system presents a number of
unexpected features, and we conclude that spin 1/2 fermions in the BCS-BEC
crossover should be classified as a new type of superfluid.
