Fotomultipliätreitä

Fotomultipliätreitä, often translated as photomultiplier tubes (PMTs), are highly sensitive light detectors. They are vacuum tubes that convert a small number of absorbed photons into a measurable electrical current. This amplification process makes them ideal for detecting extremely faint light signals.

The basic principle of a photomultiplier tube involves a photocathode, which emits electrons when struck by photons. These electrons are then accelerated towards a series of dynodes, each at a progressively higher electrical potential. When an electron strikes a dynode, it causes the emission of several secondary electrons. This cascading effect, known as secondary emission, significantly amplifies the initial electron signal. Finally, these amplified electrons are collected by an anode, producing a measurable output current proportional to the number of incident photons.

Fotomultipliätreitä are used in a wide range of scientific and industrial applications. These include particle physics experiments for detecting Cherenkov radiation, medical imaging technologies such as PET scanners, astronomical observations for studying faint celestial objects, and industrial processes requiring sensitive light measurement, like spectroscopy and fluorescence detection. Their ability to detect single photons and their fast response times are key advantages. However, they are sensitive to magnetic fields and can be damaged by exposure to bright light.