Procedure:

Therefore, the scintillation detector is especially useful for measuring the energy of γ radiation.  Unlike beta particles, gamma rays have discrete and well defined energies. Each incoming gamma ray interacts with the detector material by one or more of the following three processes;

i) Photoelectric effect which produces photoelectrons of the same energy as that of gamma ray (Eγ).

ii) Compton effect which produces Compton electrons producing a broad peak called continuous in the gamma spectrum

iii) Pair production (for E γ .>1.02 MeV) produces a photo peak at 0.51 MeV due to annihilation of electron and positron.

Figure: Integrated assembly of well type scintillation detector with photomultiplier tube and preamplifier