APPENDIX

The German Small Scale Atom Bomb

The bomb design was similar to Heisenberg’s B-III experiment at Berlin-Dahlem in early 1942 which involved alternating layers of uranium powder and paraffin inside an aluminium sphere. The neutron source was a radium-beryllium preparation dropped into the centre of the apparatus by way of a chimney.

The laboratory-built device in the diagram would have given a low-yield atomic explosion when compressed uniformly at Mach 3.5 if the uranium powder had been enriched with plutonium by leaving it to breed in a sub-reactor for some months.

That seems to have been the purpose of Heisenberg’s experiment at Leipzig commencing 2 June 1942. The bomb would be about two feet in diameter. The paraffin prevented the premature fission of the material caused by the energetic Pu²⁴⁰ isotopes.

Tests to prove the reaction probably using a lead-jacketed bomb were almost certainly carried out in the Baltic and in Norway during late 1944. These would have had almost negligible fallout and no significant blast. Hitler was against using the atom bomb operationally on doctrinal grounds.