The Physical Research on Atomic Bomb and the Rise of Nuclear Weapon Technology in World War Ⅱ

Abstract

The first idea of atomic bomb proposed by E. Fermi and, especially, L. Szilard, who was the real writer of Einstein's letter to President F D Roosevelt in 1939, was shown to be based on a fast neutron chain reaction in normal uranium which was later proved to be inert for fast neutrons At that time such an idea was also proposed independently by L. Peierls in Britain, but he soon abandoned it because of its great critical mass estimated theoretically by himself. The large scale enrichment of uranium was at first pursuited to produce a thermal nuclear chain reaction (the nuclear reactor) effectively. This stream was thus independent of that for the construction of the bomb at the early stage Those two streams above were, however, joined together in 1940 by O. Frisch and Peierls in their memorandum on a super bomb, which first showed the technological principle of atomic bomb based on the fast neutron chain reaction in pure uranium 235 In contrast to these two streams in the U.S. were kept divisitive by compartmentalization of information adopted by V.Bush, the chairman of NDRC. The idea of the Frisch-Peierls memorandum is studied in detail in comparison with the MAUD reports, the British official reports, completed in the summer of 1941. It is shown that the influence of the British research on the atomic bomb was the most important factor for the full start of the development of the bomb in the U.S. in the autumn of 1941. The problem on independence between NAS report of November 6,1941 and the MAUD reports is discussed.