Abstract
An apparatus for measurements of the heat capacity and the pressure coefficient of liquid He4 under pressure is reported. A tunnel diode oscillator is used to measure the change of the pressure. The frequency resolution and the reproducibility of the oscillator for pressure measurements are found to be 1×10-8 and 5×10-4, respectively. The temperature resolution of the system is 4×10-7K and the measurable range of pressure change is from 2×10-6bar to 30bar.
