Which absorption mechanism is most significant for intermediate energies?

The most significant absorption mechanism for intermediate energies is Compton scattering. This process occurs when an incoming photon collides with a loosely bound or free electron, resulting in a transfer of energy. The photon is scattered at an angle, and its energy is reduced, which may allow it to continue interacting with other matter.

Compton scattering is particularly relevant for intermediate photon energies, typically ranging from about 100 keV to several MeV. In this range, the interaction between the photon and the electron is more probable, influencing the attenuation of X-rays and gamma rays in various materials.

In contrast, the photoelectric effect, while very relevant at lower energies, becomes less significant as energy increases because the probability of interaction decreases with photon energy. Pair production requires very high energies (greater than 1.022 MeV) to create an electron-positron pair from a photon, making it more relevant at higher energy levels. Beta decay is a distinct process pertaining to the decay of unstable nuclei and does not directly relate to the absorption of photons as described in the context of this question.