The Idea of Direct Calibration

In normal transmission geometry any mathematical treatment of calibration to absolute units [87-90] starts from the basic differential relation among the scattering intensity in the detector, the primary intensity and the structure 

This is the differeraial definition of the absolute intensity. The total absolute intensity can be deduced by integration from Eq. (7.19) and Eq. (7.20) for any normal transmission geometry. Geometfies are discriminated by the shape and size of the irradiated volume, the image of the primary beam in the registration plane of the detector, and the dimensions of the detector elements.  

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