Which interaction with matter involves low energy x-rays (less than 10 keV)?

The interaction with matter that involves low energy x-rays, particularly those below 10 keV, is classical scattering, often referred to as Rayleigh scattering. This phenomenon occurs when low-energy photons interact with matter and are scattered without a change in energy. In this scenario, the incoming x-ray photons are typically absorbed and then re-emitted by the electrons in the atom, resulting in a change of direction but not in energy.

At low energies, this type of scattering is significant because it effectively contributes to the imaging process in radiology, especially for soft tissue imaging. Classical scattering is most prevalent in low-energy ranges, as higher-energy interactions such as the photoelectric effect or Compton scattering dominate at greater energies. The photoelectric effect, for example, is more likely to occur with higher-energy x-rays and involves the complete absorption of an x-ray photon, while pair production requires even higher energies, typically above 1.022 MeV.

In summary, classical scattering is the preferred interaction mechanism for low-energy x-rays due to its characteristics that allow for scattering without energy loss, making it relevant to imaging techniques using such low-energy photons.