fotomultipliär

Fotomultipliär, often abbreviated as PMT, is a highly sensitive photodetector. It works by converting incoming photons into a measurable electrical signal. The process begins when photons strike a photocathode, a material that emits electrons when illuminated. These emitted electrons are then accelerated towards a series of electrodes called dynodes. Each dynode is held at a progressively higher positive potential. When an electron strikes a dynode, it causes the emission of several secondary electrons. This process is repeated at each dynode in a chain, leading to a cascade of electrons. This multiplication effect significantly amplifies the initial signal. Finally, the amplified electron cloud is collected by an anode, producing a measurable current. The number of secondary electrons emitted at each dynode is dependent on the dynode material and the accelerating voltage. PMTs are known for their fast response times and ability to detect very low light levels, making them suitable for applications such as particle physics experiments, medical imaging, and astronomical observations. Their sensitivity, however, can be affected by factors like ambient temperature and magnetic fields.