Compton effect

Principle

When photons are scattered on electrons, their momentum and energy gets changed. The energy of scattered gamma-radiation is measured as a function of the angle of scatter. The Compton wavelength is determined from the measured values.

Benefits

• Experience the essence of the Nobel Prize: Compton (1927)
• Nobel Prize experiment can be performed by students within some hours
• Impressive second proof of the wave-particle dualism
• Use of a gamma detector in combination with a high precision power supply guarantees good and reproducible results

Tasks

1. Calibrate the measuring set-up with the aid of a Cs-137 calibrating source (37 kBq) and a Na-22 source (74 kBq).
2. Measure the energy of the Cs-137 661.6 keV peaks scattered at different angles and calculate the Compton wavelength from the readings taken.

Learning objectives

• Corpuscle
• Scattering
• Compton wavelength
• g-quanta
• de Broglie wavelength
• Klein-Nishina formula