What is phosphor .how it works in scintillator counter?

Phosphor is a material that exhibits the phenomenon of photoluminescence, meaning it can absorb photons and re-emit them as visible light. In a scintillator counter, phosphors are used to convert incoming ionizing radiation into visible light, which can then be detected by photodetectors. When radiation interacts with the phosphor, it excites electrons, and as these electrons return to their ground state, they release energy in the form of light. This emitted light is then amplified and counted, allowing for the measurement of radiation levels.