What portion of its energy does a photon lose during a Compton interaction?

During a Compton interaction, a photon interacts with a loosely bound or free electron, resulting in the transfer of some of its energy to the electron while continuing its path at a lower energy. This process is characterized by the scattering of the photon and the change in its wavelength, which indicates a loss of energy.

The photon does not lose all of its energy; rather, it transfers only a portion of it to the electron. The amount of energy lost depends on the angle at which the photon scatters. At larger scattering angles, the photon will lose more energy, while at smaller angles, it may lose less energy. This energy transfer makes the Compton effect significant in understanding the interactions of X-rays and gamma rays with matter, particularly in medical imaging and radiation therapy.

Thus, the correct answer reflects that during a Compton interaction, a photon loses part of its energy while still remaining in motion with a reduced energy level, rather than losing none, all, or double its energy.