Heterogeneous Example: Shielding by Copper Sheet
A 30-gauge (0.3 mm thick) copper sheet is not quite thick enough to completely block the radiation to and from a pure tin disk: the tin signal is detected through the copper, and interpreted by the quantitation software as 500 ppm tin-in-copper (Innov-X a-2000, Analytical mode, acquisition time 180 seconds, spectral region around Sn lines blown up in figure), albeit with an intensity of Sn lines that is reduced by 2-orders of magnitude (~100 x). Copper is a strong absorber of the X-Ray radiation and effective at blocking the XRF signal, compared to lighter metals such as aluminum, wood and glass.
