In which interaction do high-energy photons lose energy by ejecting electrons from atoms?

• A. Coherent scatter
• B. Photoelectric effect
• C. Compton scatter
• D. Pair production

Answer: (C)

The correct choice is rooted in the interaction known as Compton scatter. In this process, high-energy photons collide with loosely bound outer-shell electrons of atoms. When a photon strikes an electron, it transfers a portion of its energy to the electron, resulting in the electron being ejected from the atom. This interaction not only causes the electron to be emitted but also causes the photon to lose energy and change direction. The energy transferred to the electron is dependent on the angle of scattering, and the incident photon continues with reduced energy.

Through this mechanism, Compton scatter is responsible for significant energy loss in high-energy photons as they interact with matter, particularly in the context of radiography and medical imaging. Understanding this interaction is vital for professionals in the field since it influences image quality and patient dose in radiographic procedures.