Kowarski and Joliot

mp3 KOWARSKI: I went home for lunch. And here is one of those classical cases when scientists describe how they got ideas. I perfectly remember which place on what street it was that I had the idea. The idea seemed so stupidly simple. If you observe any neutrons of higher energy, that proves it. It's rather elementary.

The Paris and New York teams both found that neutrons do come out from split uranium atoms. Yes, a chain reaction was possible. Now the basic nuclear physics was in hand, and people could begin to ponder what to do with it. Over three years later, beneath the bleachers of the football stadium at the University of Chicago, Fermi led a team of physicists who released the first chain reaction. The physicist in charge at Chicago was Arthur Holly Compton. Here is his description of this historical moment...

Comptonmp3 COMPTON: We entered the balcony at one end of the room. On the balcony a dozen scientists were watching the instruments and handling the controls. Across the room was a large cubical pile of graphite and uranium blocks in which we hoped the atomic chain reaction would develop. Inserted into openings in this pile of blocks were control and safety rods. After a few preliminary tests, Fermi gave the order to withdraw the control rod another foot. We knew that that was going to be the real test. The geiger counters registering the neutrons from the reactor began to click faster and faster till their sound became a rattle. The reaction grew until there might be danger from the radiation up on the platform where we were standing. "Throw in the safety rods," came Fermi's order. The rattle of the counters fell to a slow series of clicks. For the first time, atomic power had been released. It had been controlled and stopped. Somebody handed Fermi a bottle of Italian wine and a little cheer went up. One of the things that I shall not forget is the expressions on the faces of some of the men. There was Fermi's face—one saw in him no sign of elation. The experiment had worked just as he had expected and that was that. But I remember best of all the face of Crawford Greenewalt. His eyes were shining. He had seen a miracle, and a miracle it was indeed. The dawn of a new age. As we walked back across the campus, he talked of his vision: endless supplies of power to turn the wheels of industry, new research techniques that would enrich the life of man, vast new possibilities yet hidden.

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