Absolute high-T/sub c/ superconducting radiometer with electrical-substitution for x-rays measurements

The present work considers the practical possibility of the construction of an absolute radiometer with electrical substitution for power based on the high-T c superconducting YBaCuO film bolometer cooled with liquid nitrogen to measure the power of radiation of the X-ray range circa 1μW with an accuracy of 1%. This accuracy is provided with high sensitivity of the bolometers, having the noise equivalent power about 3.8×10 -12 W/ Hz 1/2 (with modulation) and 2.6×10 -9 W (without modulation). The main sources affecting on an accuracy of the absolute measurements such as external reflection, the passage of radiation through the substrate, photo-stimulated electron emission from the receiving surface, the stability of synchrotron radiation source and instability of cryostat temperature are analysed. The radiometer can be applied to measure absolute power of white and monochromatic synchrotron radiation flows in the spectral range from 80 to 2000eV.