A rule of thumb at Fermilab has been to use 3 feet of concrete exterior to iron shielding. A recent design of a shield with a severe dimensional constraint has prompted a re-evaluation of this rule of thumb and has led to the following calculations of the concrete thickness required to nullify this problem. 4 references, 4 figures.
DOE contract number: AC02-76CH03000 OSTI Identifier 5636041 Research organization: Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States).