Compton scattering: angle and energy sharing

The relationship to understand

E′=E₀/[1+(E₀/511)(1−cosθ)] in keV; K=E₀−E′.

Try it and interpret

For an incident photon of 255.5 keV scattered through 180°, the photon retains 127.75 keV and the electron receives 127.75 keV. Return to 0°: the energy transfer vanishes in this model.

Assumptions and limitations

Free electron initially at rest, mec²≈511 keV. The diagram represents directions and energies; it computes neither collision probabilities nor dose. Deriving the conservation equations is outside the course scope, as stated in the slides.

Go further with the course

This page focuses on one concept. The full chapter (French) contains the reasoning, further examples, slides and FAQ. Demonstration values are computed or constructed within the stated model; they are not new research findings.