Crossover behavior in the isothermal susceptibility near the3Hecritical point

We present high-resolution measurements of the isothermal susceptibility of pure ${}^3\mathrm{He}$ near the liquid-gas critical point. PVT measurements were performed in the single-phase region over the reduced temperature range $3\times {10}^{-5}<{T/T}_c-1<1.5\times {10}^{-1}$. 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 ${}^3\mathrm{He}$ and Xe shows theoretically predicted universal crossover behavior.