Heterogeneous Example: Shielding of Tin by Aluminum Sheet
A 20-gauge (0.81 mm thick) aluminum sheet reduces the intensity of lines from a pure tin disk (detected through the aluminum) by ~2-fold (Innov-X a-2000, Analytical mode, acquisition time 180 seconds). The other elements detected by the quantitation algorithm are from the aluminum alloy or false positives due to the increased backscatter in the 20-30 keV region. Aluminum is a weak absorber that is not detected directly by this particular instrument, though aluminum alloys can be readily identified by their fingerprint of other elements present in the alloy. Aluminum is a relatively weak absorber of X-rays compared to the transition metals thus and nearly invisible in this specific XRF example.
