SU(2) Potentials from Large Lattices

We measure accurate values of the inter-quark potentials on a $48^{3}56$ lattice with SU(2) pure gauge theory at $ \beta =2.85$. The scale is set by extracting the string tension - we obtain ${\sqrt K}a=0.063(3)$ at $\beta =2.85.$ From a careful study of the small-$R$ potentials in the region 2 GeV $< R^{-1} < 5$ GeV, we extract a running coupling constant and estimate the scale $\Lambda _{\msbar} = 272(24)$ MeV.