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# assign08 - Physics 5110 Homework 8 (due Mar 10) March 10,...

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Physics 5110 Homework 8 (due Mar 10) March 10, 2010 1. (50 pts) 60 Co has a mean life of 5.22 years. It decays by beta emission, accompanied by gamma rays of about 1 MeV. So it is often used as a convenient source of gamma rays. (a) (20 pts) Using the example data given in Williams, Table 2.2, and supposing the example deals with a person weighing 80 kg with a projected area of 0.8 m 2 , calculate what fraction of gamma rays passing this person must be absorbed in order to reach his conclu- sion about a minimum safe distance. (Note, this exercise is doing a bit of reverse engineering on his example here.) (b) (15 pts) Is your result reasonable, given that 19 cm of water stops half of the gamma rays of energy 1 MeV and 1.1 cm of lead also stops half of them? (The energy loss mechanism is primarily pair production with a cross section proportional to the square of the atomic charge. Consider that the radiation is absorbed by tissue as well as bone.) (c) (15 pts) We want to design a lead container for the source so it can

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## This note was uploaded on 07/12/2010 for the course PHYSICS 5010 taught by Professor Rosenthaal during the Spring '10 term at Utah.

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assign08 - Physics 5110 Homework 8 (due Mar 10) March 10,...

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