Codename was - The Manhattan Project.
Do you mean the name/codename if so its codename was "Little Boy"
Fat Man.
The Manhatten Project.
It was hit with an American atom bomb.
Yes, that was its codename.
Project Manhattan.
The Manhattan project.
The project was called the Manhatten Project
Robert Julius Oppenheimer is credited with being the Father of the Atom bomb, but he was American.
Atom Bomb goes by Adam Bomb.
The atom bomb was primarily created by the Manhattan Project, a research and development project during World War II that involved scientists from the United States, the United Kingdom, and Canada. Physicists such as J. Robert Oppenheimer, Enrico Fermi, and Leo Szilard played key roles in its development.
The codename for this weapon was fat man.