is: a sensitive device used to detect light down to the level of single photons. [P10.1]
can produce: a large pulse of electrons, and hence a current pulse, for each photon absorbed. The size of the current pulse can be made proportional to the energy of the photon, and with suitable electronic equipment, individual photons can be counted and distinguished by energy. [P6.4, P10.1]
Copyright 1997, The Open University