Abstract
An unbiased approach to correct X-ray response non-uniformity in microstrip detectors has been developed based on the statistical estimation that the scattering intensity at a fixed angle from an object is expected to be constant within the Poisson noise. Raw scattering data of SiO2 glass measured by a microstrip detector module was found to show an accuracy of 12σPN at an intensity of 106 photons, where σPN is the standard deviation according to the Poisson noise. The conventional flat-field calibration has failed in correcting the data, whereas the alternative approach used in this article successfully improved the accuracy from 12σPN to 2σPN. This approach was applied to total-scattering data measured by a gapless 15-modular detector system. The quality of the data is evaluated in terms of the Bragg reflections of Si powder, the diffuse scattering of SiO2 glass, and the atomic pair distribution function of TiO2 nanoparticles and Ni powder.
Highlights
The reliability of results obtained by X-ray structural analysis depends on accuracy and precision in diffraction and scattering intensity from a sample
This applies to atomic pair distribution function (PDF) analysis of totalscattering data since real-space structure information can be obtained via no structural model
The alternative approach is based on the statistical estimation that the scattering intensity at a fixed angle from an object is expected to be constant within the Poisson noise
Summary
The reliability of results obtained by X-ray structural analysis depends on accuracy and precision in diffraction and scattering intensity from a sample. This applies to atomic pair distribution function (PDF) analysis of totalscattering data since real-space structure information can be obtained via no structural model. The total-scattering PDF method has been employed to characterize the local structure of crystalline materials as well as amorphous materials (Egami & Billinge, 2012). It is widely recognized that Rietveld analysis of Bragg diffraction data provides fundamental understanding on the average structure of crystalline materials.
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