Geophysics lecture 06: Electric (wireline) logs - Gamma ray logs
There are three modes of decay:
- Alpha decay: loss of alpha particles - convert parent into element that has nucleus containing two fewer protons
- Beta decay: loss of beta particle - convert parent into element whose nucleus contains one more proton by losing an electron
- Gamma decay: capture of beta particle - convert parent into element whose nucleus has one less proton.
Gamma ray emissions occur in all types of decay. Gamma ray logs record the radioactivity of a formation. Shale tends to have high gamma radioactive response and sand contains lower gamma radioactive response.