DESIGN AND MEASUREMENT WITH A NEW PORTABLE X-RAY CAMERA FOR FULL-FIELD FLUORESCENCE IMAGING

We present a new color X-ray camera for full-field fluorescence imaging capable of time-, energy-, and space-resolved fluorescence measurements. This new device includes a high-speed pnCCD as energy-dispersive imager, driving electronic boards and thermo electric coolers (TECs) for operating the detector. A polycapillary optics is attached in front of the beryllium entrance window to allow for imaging capability. The thickness of the window can be adapted to the specific applications, e.g. for the detection of light elements. The small housing is vacuum-sealed and can be operated as a standalone system or conditioned at regular intervals. The detector is thermally coupled to the TECs via an intermediate cooling mask enabling a CCD operating temperature around -35 C. The TECs warm side is coupled to a water-cooled copper heat exchanger. The pnCCD has an active area of (12.7 x 12.7) mm 2 and 264 x 264 pixels with 48 µm square pixel size. The column-parallel and spilt-frame readout enable frame rates up to 1,000 Hz (equivalent to 70 Mpixel/s) and a maximum count rate of 1.5 Mcps. The spectroscopic performance at this speed is expected to be around 155 eV (FWHM) for Mn-Kα. The quantum efficiency in the energy range 1 keV–10 keV approaches 100 % and still amounts to 35 % for 20 keV photons. The camera is capable of fast collection of spatially and energy resolved fluorescence images. Dedicated software enables the acquisition and the online processing of the spectral data for all 69,696 pixels, leading to a real-time visualization of the elements distribution in a sample. Results obtained with a magnifying optics are also presented. The design and the performance characteristics of this novel X-ray camera are suitable for full-field XRF, TXRF imaging with high spatial resolution or XRD either as standalone or as OEM module to be integrated into a larger system.