These plastic materials emit photons of visible light when they are struck by energetic particles. In this display they are made to fluoresce using an ultraviolet lamp. Scintillators are used extensively at TRIUMF to detect particles, in conjunction with a photomultiplier tube which amplifies the light and converts it to an electric pulse. The scintillators are covered in black tape to exclude all outside light. Often complex shaped lightpipes are used to connect the scintillator to the photomultiplier, as the phototubes are too big to fit in the crowded area around the target.
