Method for characterizing a material

A method for characterizing a material, comprising: arranging a piece of the material near a source of ionizing photons and a detector; irradiating the piece with photons and acquiring, via the detector, two energy spectra of a photon flux that has been diffused into the material at various depths, the ratio of the photon paths in the material before and after diffusion remaining constant; determining a combined attenuation function with the spectra and the paths; selecting a plurality of energy ranges from said function; calculating, in each range, a quantity that is representative of the function; and estimating, from at least two of said quantities, a physical characteristic of the material by comparison with the same quantities obtained from known materials.