At low energy levels, which type of interaction with matter predominates?

At low energy levels, the photoelectric effect predominates in interactions with matter. This phenomenon occurs when low-energy photons are absorbed by an electron in an atom, leading to the ejection of that electron from its orbit. The likelihood of this interaction increases significantly with decreasing photon energy and with materials that have high atomic numbers, as these materials have a greater probability of absorbing the lower-energy photons.

The photoelectric effect is crucial for several imaging techniques, particularly in radiography and other diagnostic imaging modalities, as it contributes to the contrast in the images by selectively absorbing photons based on tissue density and atomic composition.

In contrast, other interactions like Compton scattering, which involves the scattering of photons at intermediate energies, become more significant at higher energy levels. Pair production only occurs at much higher photon energies (above 1.022 MeV) when the energy of the photon is sufficient to create a particle-antiparticle pair. Radiolysis of water refers to the chemical reactions that occur when water is ionized by radiation and is not a direct interaction with photons but rather a secondary effect observed in biological tissue affected by radiation.