Unequal energy sharing
The energy sharing between the gamma photon and the electron that has served as a target depends on the gamma scattering angle. The most likely case is the one in which the photon is not scattered and do not lose power. The most rare case is the one where the gamma bounces backward propelling the electron forward. On average, the photon transfers only a small portion of its energy to the electron and undergoes a significant shift in direction (the values in the figure have been calculated for an energy of 500 keV).
IN2P3