Measurement of the Temperature Dependence of the Density of Liquid 4He from 0.3 to 0.7°K and Near the λ-Point
The total density of 4He has a particularly interesting temperature dependence. It has a minimum at about 1.14°K, a near-infinite slope at T λ , and a maximum at a temperature slightly above T λ . Direct measurements of the density at saturated vapor pressure have been made by Kerr and Taylor.1 Indirect measurements, inferred from the index of refraction and dielectric constant, have been reported by a number of workers, the more recent being by Chase et al.,2 Boghosian and Meyer,3 and Harris-Lowe and Smee.4 These indirect measurements can be related to the density through the use of the Clausius-Mosotti relation and the atomic polarizability. The questions of whether the Clausius-Mosotti relation is valid and whether the atomic polarizability may be considered to be temperature independent have been considered by these authors and by Kerr and Sherman.5 Very recently Roach et al.6 have measured the density from 0.1 to 0.7°K using the velocity of sound and have verified a T 4 dependence.
KeywordsHeat Exchanger Saturated Vapor Pressure Atomic Polarizability Relative Density Change Tunnel Diode Oscillator
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