(3) Interaction of high energy photons with matter - LUTH
(3) Interaction of high energy photons with matter - LUTH
(3) Interaction of high energy photons with matter - LUTH
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Comparison <strong>of</strong> photon cross-sections<br />
A. Zech, Instrumentation in High Energy Astrophysics<br />
This figure shows the<br />
different contributions to<br />
photon absorption in lead:<br />
● photoelectric absorption is<br />
only important at low<br />
energies ( < ~2 MeV)<br />
● Compton scattering leads<br />
to significant <strong>energy</strong> loss at<br />
intermediate energies<br />
● pair production becomes<br />
important for energies > 2<br />
MeV and is dominant above<br />
5 MeV and up to the <strong>high</strong>est<br />
energies.<br />
The relative contributions<br />
change somewhat for<br />
interactions <strong>with</strong> other<br />
materials (change in Z !)<br />
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