The Manhattan Project: Making the Atomic Bomb

Part I: Physics Background, 1919-1939


Lawrence's cyclotron, the Cockroft-Walton machine, and the Van de Graaff electrostatic generator, developed by Robert J. Van de Graaff at Princeton University, were particle accelerators designed to bombard the nuclei of various elements to disintegrate atoms. Attempts of the early 1930s, however, required huge amounts of energy to split atoms because the first accelerators used proton beams and alpha particles as sources of energy. Since protons and alpha particles are positively charged, they met substantial resistance from the positively charged target nucleus when they attempted to penetrate atoms. Even high-speed protons and alpha particles scored direct hits on a nucleus only approximately once in a million tries. Most simply passed by the target nucleus. Not surprisingly, Ernest Rutherford, Albert Einstein, and Niels Bohr regarded particle bombardment as useful in furthering knowledge of nuclear physics but believed it unlikely to meet public expectations of harnessing the power of the atom for practical purposes anytime in the near future. In a 1933 interview Rutherford called such expectations "moonshine."5 Einstein compared particle bombardment with shooting in the dark at scarce birds, while Bohr, the Danish Nobel laureate, agreed that the chances of taming atomic energy were remote.6

Page 4 of 99 Previous PageNext Page

Company Logo About Us | | Support | Privacy | Site Map | Weblog | Support Our Site

© Copyright 1998-2015 AJ Software & Multimedia All Rights Reserved

National Science FoundationNational Science Digital LibraryNuclear Pathways Member SiteThis project is part of the National Science Digital Library and was funded by the Division of Undergraduate Education, National Science Foundation Grant 0434253