|MadSci Network: Physics|
Well this is a complicated question and I would refer you to any college level physics book, but here is the short of it... Gamma and x-rays are part of the electromagnetic spectrum and as such have no mass or charge. The interaction between the rays and other materials is at the atomic level, by that I mean that as these rays pass near the electron clouds of other atoms they may (or may not) give (tranfer) some (or all) of their energy to a lucky electron of that atom. The electron is then offered more energy that it would otherwise have and is sent off in motion and thus "stripped" from the parent atom (this is called ionization). The interaction of an x or gamma ray is by indirectly transfering some of it's energy to these electrons which is a function of the probability that the ray will come close enough to tranfer the energy. So it is a probability relationship. The higher the probability the higher the chance of transfer of energy. So why lead?? Well it's not just lead that can stop (shield) x or gamma rays. It is a function of how many targets (atoms) you give it a chance to interact with. So the higher the target materials density (atoms/area) the higher the probability the tranfer of energy will take place. The most common high density material is... Lead!! We also use Uranium and Tungstun. Both have densities greater that lead and thus shield better because they create a higher probability the ray will indirecty interact. Hope this helps
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