T CP (7.1) where C is a constant and P the pressure is equal to P P o - h g, where is the density of the liquid and g is earth acceleration, which is 9.8m/s2. Tables of the following smoothed thermodynamic properties between 1.0 and 24°K are given in Table I: specific heat at constant pressure, specific heat at constant volume, entropy, and enthalpy. Figure 7.3: Constant-volume gas thermometer Temperature is dependent on pressure, which can be expressed by equation (7.1). Temperatures using the constant-volume gas thermometer can be measured to two. It follows that the temperature of the gas, is given by: where p 0 and p 100 are pressures at 0 o C & 100 o C respectively. The results for Θ c ( T ) are compared with the calculations of Bernardes, Horton, and Leech, and Barron and Klein, based on Mie-Lennard-Jones potentials for the interaction energy between two atoms. So accounting for atmospheric pressure, the pressure p of the gas at temperature is: note, all pressures expressed in mm of mercury. This procedure gave Θ 0 c = 74.6 ± 1.0°K for neon and Θ 0 c = 64.0 ± 0.8°K for xenon.
In the range 0.020 ≲ T Θ 0 c ≲ 0.505, the data were fitted with an expression of the form Θ c ( T ) = Θ 0 c + A T 2, where Θ 0 c is the Debye temperature at 0°K. The Interpolating Constant Volume Gas Thermometer (ICVGT), designed with a cryogenic sapphire pressure transducer and running, has now been equipped with a RUSKA pressure balance for the. The results were analyzed to obtain the temperature dependence of the Debye temperature, Θ c ( T ).
Carbon resistance thermometers were calibrated against a gas thermometer and the helium vapor-pressure scale. The specific heats of solid neon and xenon have been measured in the temperature range 1.5 to 24°K, using a calorimeter with a mechanical heat switch.
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