X-rays are an invisible, penetrating radiation that is a form of electromagnetic radiation. Find out how X-rays can produce scintillation when illuminated with certain materials with help from a science teacher in this free video on X-rays and radiation.
Hi, I'm Steve Jones, and I'm going to explain how X-rays are detected. First of all what are X-rays? They are an invisible radiation, very penetrating, in fact it is electromagnetic radiation and it's similar therefore to light, radio waves, ultraviolet and infrared radiation, so that's the kind of radiation we've got. And what effects does it have? Well because it's very highly penetrating and practically invisible, therefore, when it actually hits something it tends to go through it, and therefore it doesn't cause any effect at all and therefore you don't see it. But there are certain materials which when illuminated with X-rays will produce scintillation, in that you'll see little dots of lights. The effect of this is that the X-ray is absorbed, it gives energy to the electrons in the material, the electrons then lose that energy, but they don't lose it as X-radiation but does lower energy radiations by a series of transitions within the electron bands in the atoms, and therefore you get some light, you'll get ultraviolet radiation, you'll get other types of radiations too, so that is by scintillation. One of the most important ways in which it's detected though, is in photographic plates, because the material in photographic plates, the chemicals in photographic plates react when X-rays are incident on them. In fact this is how the X-rays were found in the first place, nobody new about X-rays until somebody actually was working in the laboratory on electrons in tubes, that is electrons being sent through evacuated tubes. And when those electrons hit something, they produced this radiation, but people didn't realize until they looked at the photographic plates and found that they were fogged, that they were all grey instead of being nice and clear. And there were often images on where something could of been left on top. The conclusion from this was that it was some kind of radiation which produced it, and that is where X-rays, X meaning, what, which, X-rays were named because they were invisible and people didn't know about them. So photographic plates were used to detect them, and now can be used to detect X-rays when we create an image of the body for example, with focused X-rays plate through the body and the photographic plate actually creates the image that we want to see. So that is basically how X-rays are detected.