State The Working Principle Of A Scintillation Counter

When an electromagnetic radiations fall on the scintillator, atoms of the scintillator are excited and when electron go back to their lower energy states, light is emitted. The light falls on the photocathode which produces electrons . These electrons fall on the first dynode where secondary electrons are emitted. These secondary electrons are fall on the next dynode which is about 100 volt higher  and more electrons are excited in multiples. By the time the electrons the electrons ereach the last dynode ( which is the anode) a lots of electrons is produced which will be large enough to constitute an electric pulse  that can be further amplified by an electronic amplifier. Pulse from this amplifier are then electronically counted . By this techniques individual radiation particles of very low energy can be counted