Which interaction results in a free electron being ejected?

The correct answer pertains to the Compton interaction, which is a significant process in the interaction of X-rays and gamma rays with matter. In the Compton effect, a photon collides with a loosely bound or free electron. During this interaction, the photon transfers part of its energy to the electron, resulting in the ejection of the electron from its atom. This energy transfer causes the electron to become a free electron, allowing it to move independently.

The significance of this process lies in its ability to demonstrate the dual particle-wave nature of photons, and it plays a crucial role in understanding how radiation interacts with biological tissues in a medical setting. This ejected electron, or secondary electron, can then contribute to ionization processes as it moves through matter, which is especially relevant in the field of dosimetry where radiation dose calculations are critical.

In contrast, other interactions, such as elastic scattering, do not result in the ejection of electrons; instead, the photons retain their energy and just change direction. The photoelectric effect involves a photon being completely absorbed by an electron, leading to ejection, but it is characterized by the absorption of the full photon energy rather than scattering. Pair production requires high-energy photons interacting with a nucleus to create an electron