Quantitative XRF analysis in typical archaeometric applications

Quantitative XRF analyses addressed to archaeometric demands are hampered when employing energy dispersive spectroscopy in the three following cases: i. So called dark matrix sample composed of light elements where absorption correction can be evaluated by resorting to incoherent or coherent to incoherent ratio scattering. ii. Non homogeneous composition on microscopic scale, as for pigment layers, where quantitative information on pigment dilution can be achieved by proper models where medium absorption is disregarded and grain pigment contribution is evaluated by linear approximation of absorption valid for small volume pigment grains. iii. Irregular shape of metallic sample and/or incorrect positioning due to the use of portable instruments which prevents from direct comparison with standard reference with plane surface and different position in the experimental set up. We have already shown that exploiting a geometry where excitation and detection direction are as much coincident as possible one obtains substantial reduction of the error depending on irregular shape in quantitative analysis. In the present contribution we present the encouraging experimental results achieved employing an annular silicon drift detector so that the condition of coincidence for incoming and out going X-Ray directions is nearly achieved.