Compton effect

The gamma rays from a ¹³⁷Cs (662 keV) source are directed onto a thin metal bar, where a proportion of the photons is elastically scattered by electrons. The photons scattered at an angle are detected with a sodium iodide crystal and a photomultiplier. The energy spectrum of the scattered gamma rays is thus obtained as a function of the scattering angle.

Caution: Radioactive radiation!
Use the source only for short time, otherwise shield the source and keep distance!!