Dielectric microcalorimeter utilizing a quantum ferroelectric thermometer

A dielectric capacitance thermometer was fabricated using KTa_0.99Nb_0.01O₃ (KTN) quantum ferroelectrics. The electric capacitance of the KTN thermometer was measured as a function of temperature from 0.1 to 300 K using the four-terminal-pair method. The KTN thermometer exhibited a dependence of the electric capacitance on the temperature that showed promise for using the thermometer as a microcalorimeter. A prototype of the dielectric microcalorimeter (DMC) was assembled with the KTN thermometer and irradiated with alpha rays with an energy of 5.5 MeV at a temperature of 100 mK. When applying a DC bias voltage to the DMC, the detection signals could be observed at the output of the preamplifier. A response of the DMC to alpha rays was obtained despite the poor signal-to-noise ratio caused by long wirings for the detection signal readout inside the refrigerator.