PHOTODIODE ARRAY FOR POSITION-SENSITIVE DETECTION USING HIGH X-RAY FLUX PROVIDED BY SYNCHROTRON RADIATION.

Synchrotron radiation provides a high intensity source over a large range of wavelengths. This is the prominent quality that has laid the foundations of the EXAFS development (Extended X-ray Absorption Fine Structure). EXAFS data can be collected in different ways. A full scan requires 5 to 10 min, compared to the one-day data collection of a conventional Bremsstrahlung X-ray tube. Recently, by using the new photodiode array (R 1024 SFX) manufactured by Reticon, it has been possible to reduce the data collection time to less than 100 ms. The key elements of this new EXAFS method are a dispersive optics combined with a position sensitive detector able to work under very high flux conditions. The total aperture of 2500 mu m multiplied by 25 mu m for each pixel is well suited to spectroscopic applications. Besides its high dynamic range ( greater than 10**4) and its linearity, the rapidity of the readout allows a flux of 10**9-10**1**0 photons/s over the 1024 sensing elements.