|MadSci Network: Engineering|
To answer the question gold would be slightly less effective than lead as a gamma/x-ray sheild. No activation occurs with these interactions. Only with neutrons do you see activation. The sheilding of radiation is based on the type and energy of the radiation. The alpha and beta radiations are particulate forms of radiation. They have mass and an associated electrical charge. Gamma and x-rays are electomagnetic radiation. It has no mass or charge. Simply put for alpha radiation it can not travel but a few millimeters in air and even less in other more dense materials. A few sheets of paper will stop alpha particles. Beta radiation is simply an electron and it can travel further in air and materials. Most common beta emmiters are stopped by a few centimeters of wood or plastic. Gamma & x-ray are the most penetrating forms of these radiations. Because they are forms of elecrtomagnetic radiation they do not directly "collide" with other materials to be stopped. Their interaction is based on the probability that they will interact with the atoms contained in the material they are passing through. To increase the probability they will interact you need to increase the atom density of the material they are passing through. Lead has a high atomic number and thus has a high atom density so it makes a good gamma/x-ray sheild. The higher the atomic number the better the sheild. Uranium is a great sheild for gamma/x-ray however it is naturally radioactive so it is not often used except is the most exstream cases. So if you look up atomic numbers you can rank the effectiveness of materials as shields for gamma/x-rays.
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