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What is the attenuation coefficient for lead and aluminum?

The linear attenuation coefficient, and how to find the attenuation coefficient mass, knowing Their densities? I've been looking everywhere, in books, the Internet. It's incredible, there is no single place that has the information. Please help me to find it. If you have the source, please give me your website as well. Thank you! I do not mean what is the definition of coefficient attenuation. I meant that the attenuation coefficient value for lead and aluminum

The http://physics.nist.gov/cgi-bin/ffast/chooseElement.pl?filename=form.html&elNum=82&elName=Lead&elSym=Pb linear attenuation coefficient provides an indication of the effectiveness of a given material is, per unit thickness, in promoting the interaction of photons. The higher the value of the attenuation coefficient, the more likely it is that a given energy photons interact in a given thickness of material. The magnitude of the coefficient varies by material and, as you suppose, with the photon energy. While the specific values of the attenuation coefficient can range from materials for photons of a specific energy, generalized forms of the plots (neglecting fine details) of attenuation coefficient versus photon energy are similar between different materials. In general, these forms show high values of attenuation coefficient at low photon energies decrease with increasing energy of the photons pass through a minimum value, wider, and then increase as the energy continues to rise. The reason for this general form is that the coefficient linear attenuation consists of three main components, each of which depends on a different type of interaction of photons. At low energies, a process called the photoelectric effect is the dominant mode of interaction that has strong energy dependence, decreased approximately as the inverse cube energy. At intermediate energies the dominant interaction is Compton scattering, which shows a general decrease in the energy increasing. Finally, at higher energies the dominant process becomes the pair production, and this shows an increase with increasing energy (the absolute minimum energy in which this process can occur is 1.022 MeV). Energy thus lower photoelectric contribution is sharply decreasing causing the decrease in the coefficient attenuation with increasing energy, the Compton process becomes dominant and continues to decline (but at a slower pace than did the photoelectric process); when the energy reaches high enough the contribution of pair production exceed the Compton attenuation coefficient and eventually start to increase. To compare, we could compare the two materials, water and lead, which have very different effective atomic numbers (a key determinant of the values specific attenuation coefficients), about 7 water and 82 for lead. In water attenuation coefficient at 10 keV is about 5.0 per cm, Compton contribution to the attenuation coefficient is equal to the photoelectric contribution at about 25 keV, and the contribution of pair production is equal to the Compton process, about 30 MeV, the total value of the attenuation coefficient decreases to an energy of about 100 MeV is reached, when the contribution Pair production becomes large enough to offset the contribution of Compton steadily diminishing. In the lead, the photoelectric and Compton contributions are equal at about 600 keV, the Compton and pair production contributions are equal at about 2 MeV, and the attenuation coefficient begins to increase in value addition time at 4 MeV. In addition to the generalized form discussed above, there are also some small but important discontinuities that occur at low energies. These discontinuities show sudden changes in the contribution photoelectric attenuation coefficient when the photon energy just exceeds the binding energy of the electron in a shell of an atom of the given material. These abrupt changes are most noticeable in the higher atomic number materials because the binding energies of electrons in the inner electron shells of these materials are sufficiently high that are comparable to some ionizing photon energies of interest. For example, lead sample a sharp increase in the attenuation coefficient in about 88 keV, which is about the binding energy of K-shell electrons of lead. Discontinuities in the water, often referred to as absorption edges would not be evident until the decline of energy below 1 keV.