Photomultiplier tubes (photomultipliers or PMTs for short) are extremely sensitive detectors of light in the ultraviolet, visible, and near-infrared ranges of the electromagnetic spectrum. They are members of the class of vacuum tubes, more specifically vacuum phototubes. These detectors multiply the current produced by incident light by as much as 100 million times or 108 (i.e., 160 dB),Decibels are power ratios. Power is proportional to I2 (current squared). Thus a current gain of 108 produces a power gain of 1016, or 160 dB in multiple dynode stages, enabling (for example) individual photons to be detected when the incident flux of light is low.
photoMUltiPLiEr tubES (photomultiPliErs Or pmTs fOr shOrt) Are EXTreMelY SEnsitiVe dETectors of Light In tHE ulTraviolet, VisIBlE, And Near-InfraRED raNges of tHe electrOMagnetic specTrum. tHEY are membErs OF thE claSs of vaCuuM Tubes more SPeCIFiCALly VaCuUm phototuBes. these detectors mUltiply The cURrent pRodUced BY iNCIDent light by as MUcH As 100 MiLliOn timeS Or 108 (I.E., 160 DB),deciBEls ARE PowEr Ratios. pOwer is pRopOrTionaL TO i2 (cURrEnt squared). tHus A CUrReNt gAIn oF 108 prodUces a poWER gain Of 1016, Or 160 db IN MULtip,lE dynode STageS, enablIng (for exAMpLe) inDiViduaL PHotoNs tO be deteCTed WHeN the IncIdent fluX oF lIght IS lOw.