Some notes on where these letters are used Alpha particles are made of 2 protons and 2 neutrons. Beta is the second letter B , an example of use is Beta Blocker drugs which block beta receptors in the blood vessels and lower blood pressure. Gamma rays are very energetic rays in space . When matter and antimatter collide they give out gamma rays Delta waves are slow waves from the front of the brain in deep sleep.
Theta waves are arousal waves in the brain.
Note the second small form of sigma is used as a plural at the end of a word ege animals. Omega is the last 24th letter and means final as in alpha and omega -first and last.