Principle

The radiation of ¹³⁷Cs and ²²Na is measured with a scintillation detector and the energy spectrum determined with a multi channel analyzer. The fractions of the spectra caused by Compton scattering and those caused by the photoelectric effect are determined on the basis of their areas. The results are used for determining the ratio of the effective cross-sections and examining its energy dependence.

Tasks

1. Measurement of the g-spectra of ²²Na and ¹³⁷Cs, using a scintillation detector.
2. Determination of the ratio of the specific effective cross-sections due to the Compton effect and the photoelectric effect in photons having energy values of 511, 662 and 1275 keV.

Learning objectives

• g-radiation
• Interaction with material
• Photoelectric effect
• Compton effect
• Pair formation
• Detection probability
• Scintillation detectors