A 1-mCi source of 60Co is placed in the center of a cylindrical water-filled tank with an inside…

A 1-mCi
source of 60Co is placed in the center of a cylindrical water-filled tank with
an inside diameter of 20 cm and depth of 100 cm. The tank is make of iron with
a wall thickness of 1 cm. What is the uncollided flux density at the outer
surface of the tank nearest the source?