COMPOSITE BOLOMETER BASED ON HIGH-TEMPERATURE SUPERCONDUCTING BI2SR2CACU2O8-INFRARED(X CRYSTALS FOR APPLICATION IN THE FAR)

We discuss the feasibility of a new type of high temperature supercond ucting bolometer operating in the sub-millimeter region (lambda > 300 mum) of the spectrum in the temperature range 80K divided-by 100K. We use the sharp resistive transition Of Bi2Sr2CaCu2O8+x superconducting single crystals as sensitive thermometer. The sensor is thermally coup led to a thin diamond substrate covered on the back side with a bismut h film that performs the absorbtion of the radiation. Such a detector should have large sensitive area and short time response due to the lo w heat capacity of both crystal and substrate. We describe the results of the electrical bolometric characterization, noise measurements and optical calibration carried out on the first prototype and use them t o predict the Noise Equivalent Power (NEP) of a well designed detector .