Pixel Drift Detector (PixDD) – SIRIO: an X-ray spectroscopic system with high energy resolution at room temperature

An X-ray spectroscopic system composed of a novel Pixel Drift Detector (PixDD) and SIRIO charge sensitive preamplifier is presented. The PixDD prototype is a 4 × 4 matrix of 500 μm × 500 μm pixels, manufactured on a 450 μm thick, 9 kΩcm silicon wafer. The anode current of a pixel is 0.7 pA at +20 ◦C and decreases down to tens of fA for temperatures lower than 0 ◦C. The low current together with the low pixel capacitance (30 fF independent of the pixel area), make PixDD an extremely low noise detector. When PixDD is coupled to the ultra-low noise SIRIO CMOS preamplifier, intrinsic spectral line widths (pulser) of 51 eV FWHM (5.9 electrons r.m.s.) and 130 eV FWHM at 5.9 keV (55Fe) are obtained at +20 ◦C. If the system is slightly cooled down to 0 ◦C, the FWHMs decrease down to 38.5 eV (4.5 electrons r.m.s) and 127 eV for the pulser and the 5.9 keV line respectively. The high energy resolution of PixDD joined with its intrinsic position sensitivity and the possibility to sustain high photon fluxes open new perspectives in X-ray spectroscopic imaging in the 0.1 keV–20 keV energy range.