Module 2 : Experimental Nuclear Physics

Discovering the Structure of the Atom

Gaseous Ionisation Detectors

Gaseous Ionisation Chambers use the ionising effect of radiation to generate electrical signals.A charged particle passing through the detector will ionise the gas molecules - giving an atomic electron sufficient energy to escape the atom and leaving a positive ion and negative electron. A voltage applied between the anode and cathode (see the diagram below) creates an electric field, which causes the ions to drift to opposite sides. The collection of these ions on the electrodes will register a current, signalling the presence of a particle.