Method and device for recognizing a material with its transmission function

The invention relates to a nature method for characterizing a material, comprising: - disposing at least one sample (100) of the material between a source (1) of X-rays, and a detector; - carry out, using the X-ray source, X N radiation spectra transmitted through said material, each for a duration .DELTA.t; - calculating the transfer function of this material as a function of energy or detection channel; - in each of at least two energy regions, calculate the integral of the transmission function, thereby forming at least a first coefficient (α1) and a second transmission coefficient (α2) of transmission.