A low-temperature ac microcalorimeter

The requirements for a low temperature ac microcalorimeter for heat-capacity and thermal-diffusivity measurements of microsamples weighted about 1 mg are considered. The influence of the wire-heat-leakage on the measured temperature oscillations is discussed. It is shown that the influence can lead to incorrect measurements. A proper choice of materials and external parameters enables the construction of a calorimeter with high sensitivity of about 10^-8 J/K at 5 K. The presented calorimeter gives an opportunity to measure the heat capacity dependencies in the steady-state mode with a resolution ~0.01 K