Measurements of the Dielectric Constant of Solid Helium at Low Temperatures

A careful measurement of the dielectric constant of solid ⁴He was made to search for signatures associated with the reported onset of nonclassical rotational inertia and shear modulus stiffening. The samples studied include zero-pressure liquid, solid-liquid mixtures on the melting-curve and solid helium. It was found that the dielectric constant of solid ⁴He decreases smoothly with temperature below 300?mK, showing no measurable anomalies down to 50?mK. The new measurements do not show the anomalous upturn effect that was reported in our previous measurements.