Faculty Sponsor's Department(s):
Heat capacity is a helpful way to study physical changes of a material of interest; it is a thermodynamic quantity that is related to many fundamental properties of a physical system. A microcalorimeter has been constructed to measure the heat capacity of sample sizes on the order of milligrams down to temperatures of near absolute zero (~7 K) using the thermal relaxation of heat pulses. The motivation behind using a microcalorimeter can be explained by the proportional relationship between the thermal relaxation time, τ and the sample heat capacity, C. A small sample mass, and thus a smaller C, aids in avoiding inordinately long measurement times. This system employs a thin film heater and a temperature sensor that have been thermally anchored on a specially designed sapphire plate measuring only 3 mm in diameter. The diminutive size of the calorimeter reduces the absolute heat capacity of the measuring apparatus to optimize the precision and accuracy of the collected data with the goal of outperforming currently available commercial calorimetry solutions. To accompany the extremely sensitive hardware of the system, MATLAB and LabVIEW were utilized for the programming of the data collection and analysis software. A Chebyshev polynomial fit is used for the fitting and optimum interpolation of the heat capacity and thermometry calibration data. The software is designed to provide a user-friendly interface for data collection and analysis, with the goal of implementation in a dilution refrigerator system for testing in the exceptionally low millikelvin temperature regimes.