Compton Scattering (Photon Billiards)

Fire an X-ray or gamma photon at an electron and watch it bounce off with less energy — the wavelength shift depends only on the angle, which is the evidence that light comes in particles.

Still frame from the Compton Scattering (Photon Billiards) simulation
Requires Launch

What you can adjust

Incident photon energy
8.05 – 1250 keV

The X-ray or gamma photon's energy before it hits the electron. A higher-energy photon hands a bigger fraction of its energy to the electron for the same scattering angle.

Scattering angle (theta)
0 – 180 °

The angle the photon comes off at, measured from its original direction. 0 degrees means it barely deflects at all (no energy loss); 180 degrees is a dead-on backscatter (the biggest possible energy loss).

Animation duration
1 – 4 s

How long the clip runs — the photon travels in, then the scattered photon and recoil electron fly apart.