PMT
Produce current at their anodes when photons impinge upon their light-sensitive cathodes
Require external powersource
Their gain is as high as 107 electrons out per photon in
Noise can be generated from thermionic emission of electrons - this is called “dark current”
If very low levels of signal are available, PMTs are often cooled to reduce heat effects
Spectral response of PMTs is determined by the composition of the photocathode
Bi-alkali PMTs have peak sensitivity at 400 nm
Multialkali PMTs extend to 750 nm
Gallium Arsenide (GaAs) cathodes operate from 300-850 nm (very costly and have lower gain)
Notes:
This slide covers the properties behind photomultiplier tubes. This slide may have too much information on it and might be broken down in the future.
