In this Letter, field ionization of O-2 doped into Ne is used to extract the minimum energy V-0 of the conduction band in dense Ne, and a novel critical point effect is observed. These results represent the first complete view of V-0 from low density to the density of the triple point liquid for a repulsive fluid (i.e., a fluid with a positive zero-kinetic-energy electron scattering length). The recently developed local Wigner-Seitz model is shown to fit these data accurately both at noncritical temperatures and on an isotherm near the critical isotherm. (C) 2010 Elsevier B.V. All rights reserved.