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1944: Developing the Bomb

1944: Developing the Bomb

Timeline Image: 
B Reactor Workers

1944 May 9

The 50 milliwatt Water Boiler reactor goes critical at Los Alamos, NM. Holding 565 g of U-235 (in the form of 14.7% enriched uranyl sulfate), dissolved in a 12" sphere of water, this is the world's first reactor to use enriched uranium, and the first critical assembly constructed at Los Alamos.

1944 May

Two British scientists join Los Alamos, NM, and prove to have important impacts on the implosion program. Geoffrey Taylor (arrived May 24) points out implosion instability problems (especially the Rayleigh-Taylor instability), which ultimately leads to a very conservative design to minimize possible instability. James Tuck brings the idea of explosives lenses for detonation wave shaping (2-D lenses for plane wave generation originally proposed by M. J. Poole in England, 1942), but suggests developing 3-D lenses to create a spherical implosion.

1944 May

Edward Teller is removed as head of the implosion theory group, and also from fission weapon research entirely, due to conflicts with Hans Bethe and his increasing obsession with the idea of the Super (hydrogen bomb).

1944 May

Six months after the start of accelerated implosion research, little progress towards successful implosion has been made. Inadequate diagnostic equipment prevent accurate measurement of implosion process, and no scheme to avoid asymmetry has yet shown promise. The current approach is to use many simultaneous detonation points over the surface of a sphere, and try different methods of inert spacers or gaps to suppress the shaped charge-like jets that form when detonation waves from adjacent initiation points merge.

1944 Apr 5-15

On April 5 the first sample of reactor produced plutonium arrives from Oak Ridge, TN. Emilio Segre immediately begins monitoring its spontaneous fission rate. By April 15 he makes a preliminary estimate of a spontaneous fission rate of over 50 fissions/kg-sec (due to Pu-240 contamination), far too high for gun assembly. The report is kept quiet due to limited statistics, and observations continue.