  We directly measured the normalized $\it{s}$-wave scattering cross-section of
ultracold $^{40}\rm{K}$ atoms across a magnetic-field Feshbach resonance by
colliding pairs of degenerate Fermi gases (DFGs) and imaging the scattered
atoms. We extracted the scattered fraction for a range of bias magnetic fields,
and measured the resonance location to be $B_0 = 20.206(15)$ mT with width
$\Delta = 1.0(5)$ mT. To optimize the signal-to-noise ratio of atom number in
scattering images, we developed techniques to interpret absorption images in a
regime where recoil induced detuning corrections are significant. These imaging
techniques are generally applicable to experiments with lighter alkalis that
would benefit from maximizing signal-to-noise ratio on atom number counting at
the expense of spatial imaging resolution.
