An electron multiplier relies on a series of biased electrodes called dynodes. When a single electron strikes the first dynode, it knocks loose several secondary electrons, which are accelerated into the next dynode, creating a cascading avalanche of charge. They are used in photomultiplier tubes and mass spectrometers to detect single photons or particles that would otherwise be lost in the noise floor of standard amplifiers.
The mass spec is losing sensitivity, so we probably need to replace the electron multiplier.
Related terms
Photomultiplier tube
A highly sensitive vacuum tube that detects light and amplifies the resulting electron flow.
Vacuum tube
An evacuated glass or metal envelope containing electrodes used to control electron flow.
Cathode ray tube
A vacuum tube containing one or more electron guns and a phosphorescent screen used to display images.