Crossover Behavior In The Isothermal Susceptibility Near The He-3 Critical Point

We present high-resolution measurements of the isothermal susceptibility of pure He-3 near the liquid-gas critical point. PVT measurements were performed in the single-phase region over the reduced temperature range 3 x 10(-5) < T/T-c - 1 < 1.5 X 10(-1). The crossover behavior of the susceptibility along the critical isochore was analyzed using a field-theoretical renormalization-group calculation based on the phi (4) model. A similar crossover analysis was performed on previously obtained Xe susceptibility measurements. A comparison of the rescaled susceptibility for He-3 and Xe shows theoretically predicted universal crossover behavior.