litres of heavy water, the small nickel ball with the radiumberyllium neutron source being at its centre. This Präparat played a twofold role. It emitted neutrons into the heavy water where they lost a degree of momentum before proceeding into the surrounding uranium metal powder. Here they fissioned U 235 atoms to release more neutrons into the reaction or were captured by U 238 isotopes to decay into plutonium. Additionally, gamma radiation from the neutron source generated photoneutrons in the heavy water and these also entered the uranium. Over a period of many months this âexperimentâ would be a subtle means of uranium enrichment, since a measureable proportion of the U 238 capture band converted into the fissile isotopes of plutonium. After his return to Leipzig University on 23 June 1942, it was noticed that the sphere, which had been quietly fissioning for three weeks, was leaking bubbles. The equipment was raised from the water and an access hatch opened to inspect the interior. A hissing sound was followed by a jet of flame. The sphere was hosed down with water until the fire appeared to be extinguished. The heavy water was then drained from the inner sphere to prevent its accidental contamination, after which the main sphere was re-sealed and lowered back into the water tank for safety. A few hours later the apparatus began to give off bubbles once more and the water in the containing tank began to boil. On closer inspection it was seen that the sphere was vibrating and beginning to swell in size. The laboratory was evacuated and shortly after there was an explosion involving a hailstorm of burning uranium powder. The fire brigade succeeded in dowsing all fires except that in the sphere which was allowed to burn out over the next few days.
How did this fire start? Possibly fissioned material in the powdered uranium began to warm up. As it expanded, the pressure cracked the seal holding the two aluminium hemispheres together, allowing water to enter from the shielding tank. This would have oxidized the uranium, generating more heat. But the ignition source is a mystery. The material burnt out and the attempt to do whatever it was that was being attempted failed. So terminated this series of experiments, the purpose of the last of which seems not to have been questioned too closely previously.
Professor Goudsmit Not Deceived
The only military scientist on record as believing that Heisenberg had been involved in an attempt to build a German atom bomb is Professor Samuel Goudsmit. In his book Alsos- The Failure in German Science (Sigma, London, 1947) on page 183 Professor Goudsmit reproduced two sketches contained in Heisenbergâs official German wartime report respecting the B-III uranium/paraffin experiment. Under a drawing of the chimneyed sphere appeared the caption âGermanyâs Atom Bombâ and the words âGermanyâs experimental uranium pile which they believed would make a bombâ. Beside a slightly adulterated version of the cut-through diagram he wrote, âDiagram for the experimental âbombâ which consisted of layers of uranium and paraffinâ. Professor Goudsmit was Jewish and had lost both parents at Auschwitz. His book was a non-scientific publication very popular at the time and it is possible that he was merely attempting to ridicule Heisenbergâs scientific circle. But one can interpret it in another sense. Perhaps this was as far as Goudsmit, who was restrained by the various US secrecy laws, was permitted to go in print with his allegation. Joke or not, this device would have worked as the warhead of a V-2 rocket.
After five or six months in the sub-reactor sphere, the uranium powder was enriched with plutonium. In the bomb casing the material would be stacked in alternate layers with paraffin. The paraffin in the top hemisphere layers prevent premature fission by the highly radioactive Pu 240 plutonium isotopes which would otherwise spoil
How did this fire start? Possibly fissioned material in the powdered uranium began to warm up. As it expanded, the pressure cracked the seal holding the two aluminium hemispheres together, allowing water to enter from the shielding tank. This would have oxidized the uranium, generating more heat. But the ignition source is a mystery. The material burnt out and the attempt to do whatever it was that was being attempted failed. So terminated this series of experiments, the purpose of the last of which seems not to have been questioned too closely previously.
Professor Goudsmit Not Deceived
The only military scientist on record as believing that Heisenberg had been involved in an attempt to build a German atom bomb is Professor Samuel Goudsmit. In his book Alsos- The Failure in German Science (Sigma, London, 1947) on page 183 Professor Goudsmit reproduced two sketches contained in Heisenbergâs official German wartime report respecting the B-III uranium/paraffin experiment. Under a drawing of the chimneyed sphere appeared the caption âGermanyâs Atom Bombâ and the words âGermanyâs experimental uranium pile which they believed would make a bombâ. Beside a slightly adulterated version of the cut-through diagram he wrote, âDiagram for the experimental âbombâ which consisted of layers of uranium and paraffinâ. Professor Goudsmit was Jewish and had lost both parents at Auschwitz. His book was a non-scientific publication very popular at the time and it is possible that he was merely attempting to ridicule Heisenbergâs scientific circle. But one can interpret it in another sense. Perhaps this was as far as Goudsmit, who was restrained by the various US secrecy laws, was permitted to go in print with his allegation. Joke or not, this device would have worked as the warhead of a V-2 rocket.
After five or six months in the sub-reactor sphere, the uranium powder was enriched with plutonium. In the bomb casing the material would be stacked in alternate layers with paraffin. The paraffin in the top hemisphere layers prevent premature fission by the highly radioactive Pu 240 plutonium isotopes which would otherwise spoil
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