Dielectric Constant Measurements of Solid 4He

Careful measurements of the dielectric properties of solid He-4 have been carried out down to 35 mK, considerably lower than the temperature range of previous studies. The sample was prepared from high purity gas with He-3 concentrations of the order of 200 ppb and were formed by the blocked capillary method. The molar volume of the sample was 20.30 cm(3). The dielectric constant of the samples was found to be independent of temperature down to 120 mK before showing a continuous increase with decreasing temperature and saturating below 50 mK. The total increase in epsilon is 2 parts in 10(-5). The temperature dependence of epsilon mimics the increase in the resonant frequency found in the torsional oscillator studies and also the increase found in the shear modulus measurements.