In the course of several years of intensive research, the National Bureau of Standards has developed systematic methods for solving a great many of the radiation penetration problems associated with nuclear power and propulsion reactors, radiation fallout, and mechanical uses of radiation. Starting on a small scale in 1948, the program has rapidly broadened as a series of advances in theory and computational technique have extended the range of problems that could be treated.
, "Penetration and Diffusion of Gamma Rays," Appl. Spectrosc. 11, 49-56 (1957)