On July 16, 1945 the first nuclear fission device, called the “Trinity” test, occurred in Alamogordo, N.M. The following month, the atomic bombs “Little Boy” and “Fat Man” were exploded over Hiroshima and Nagasaki, Japan, respectively, and led to the surrender of Japan and the end of World War II. This presentation summarizes how the Manhattan Engineer District designed, developed and produced these devices from theoretical concepts for the fission chain reaction in under three years. This vast and highly classified project involved tens of thousands of workers and the construction of major facilities in several locations involving numerous supporting
organizations. Descriptions will be given of the science and engineering issues that were addressed for the two types of atomic bombs used in WW II.
Suggested reading: The History and Science of the Manhattan Project, Second Edition, Bruce C. Reed (Springer-Verlag GmbH, Germany, 2019)