fotomultiplikátorok

Fotomultiplikátorok, or photomultiplier tubes (PMTs), are highly sensitive vacuum tubes used to detect very low levels of light. They work by converting photons into an electrical signal that can be amplified. When a photon strikes the photocathode inside the tube, it ejects an electron through the photoelectric effect. This electron is then accelerated towards a series of electrodes called dynodes, which are held at progressively higher positive voltages. As the electron strikes each dynode, it causes the emission of multiple secondary electrons. This process is repeated through several dynode stages, resulting in a cascade of electrons. Finally, this amplified electron cascade is collected by the anode, producing a measurable electrical current. The gain, or amplification factor, of a PMT can be very high, often in the millions, making them ideal for detecting single photons or extremely faint light sources. They are widely used in scientific research, medical imaging, high-energy physics experiments, and night vision devices. Their sensitivity, fast response time, and wide dynamic range are key advantages. However, PMTs are also susceptible to magnetic fields and can be damaged by exposure to bright light.