  We provide a practical approach to the molecular production via linear
downward sweeps of Feshbach resonances in degenerate Fermi gases containing
incoherent mixtures of two atomic spin states. We show that the efficiency of
the association of atoms is determined just by the Landau-Zener parameter in
addition to the density of the gas. Our approach of pairwise summation of the
microscopic binary transition probabilities leads to an intuitive explanation
for the observed saturation of the molecular production and recovers all atomic
loss curves of C.A. Regal et al. [Nature (London) 427, 47 (2003)] as well as
K.E. Strecker et al. [Phys. Rev. Lett. 91, 080406 (2003)] without adjustable
parameters.
