SINGLE-PHOTON IMAGING X-RAY SPECTROMETERS USING LOW-NOISE CURRENT PREAMPLIFIERS WITH DC VOLTAGE BIAS

We have developed superconducting single-photon imaging x-ray detector s with an energy resolution of 54 eV at 6 keV and a spatial resolution of 1 mu m over an effective length of 40 mu m. They utilize a current -sensitive low-noise preamplifier with a de voltage bias. It has a sig nal bandwidth of 300 kHz, current noise of i(n) = 0.26 pA/root Hz and voltage noise of e(n) = 0.5 nV/root Hz with an input capacitance of 20 0 pF under operating conditions. Injected pulses with a charge Q = 3.7 .10(6) electrons have been measured with a standard deviation sigma(Q) = 3400 electrons, corresponding to an electronic noise of 13 eV at 6 keV.