The Intensity of Gamma Rays Passing Through a Material as a Function

question 19

Multiple Choice

The intensity of gamma rays passing through a material as a function of thickness, x is given by where n is the number of atoms per cm³ and $\sigma$ is the absorption cross section. If the intensity of gamma rays of a particular energy is reduced by half when they passed through 1 cm of lead, what is the absorption cross section for the gamma rays? The density of lead is 11.3 g/cm³ and its molar mass is 207 g.

• A) 3.5 * 10^{- 22} cm²
• B) 6.8 * 10 ²² cm²
• C) 4.6 * 10 ²³ cm²
• D) 2.1 * 10 ²³ cm²
• E) 8.4 * 10 ²⁴ cm²

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