Patent ID: 7376215

Claim:
An apparatus for measuring relative composition by weight of ash material elements included in a paper product, the apparatus comprising: an X-ray source having a known X-ray spectra at each of a plurality of applied energies and an X-ray detector, said X-ray source and X-ray detector spaced apart for receiving said paper product; a voltage power supply that powers the X-ray source at a plurality of applied energies, said X-ray detector providing a plurality of X-ray response measurements at each of said plurality of applied energies, wherein a plurality of X-ray response measurements are obtained from the X-ray detector with said paper product between said X-ray source and said X-ray detector and, a plurality of X-ray response measurements are obtained from the X-ray detector without said paper product between said X-ray source and said X-ray detector, wherein an actual sensor response is obtained based on both said plurality of measurements; a means for predicting a sensor response based on said known X-ray response spectra and known absorption coefficient values for each component of said paper product at each of said plurality of applied energies; and, a means for computing ash component weights by comparing said actual sensor response and said predicted sensor response, and extracting relative weights of ash material elements based on said comparison.