Radioactivity

Abstract

Radioactivity originates in the nucleus of an atom and is a random process. Radioactive substances produce radiation which has the ability to ionise the air surrounding them and it is this property which is used to detect them. In a cloud chamber, alcohol vapour condenses along the path of the ionising radiation. In a Geiger—Müller tube, a pulse of current, produced by the ionising particle entering the tube, flows between the central electrode and the metal tube surrounding it. These pulses may be counted by a ratemeter (in counts per second) or by a scalar which gives the total counts.