6
JOURNEY TO THE NEW WORLD
It was a gray winter morning. The date was December 2, 1942. The place, The University of Chicago. Here at Stagg Field, under the football stands, was a large empty room that had once been a squash court.
None of the students who hurried by on the way to class paid much attention to a few men who passed through the door into the long unused room. No one knew that in that room one of the greatest events in the history of science was about to take place. No one knew that the atomic age would be born that day.
The men who had gathered in the secret room were some of the finest scientists in the world. The leader of the group was Enrico Fermi (En-REE-ko FER-mee), an Italian scientist who had come to the United States.
For some weeks the men had been quietly at work, carefully stacking a huge pile of pure graphite bricks. Here and there among the bricks they placed pieces of uranium. Fermi believed that when the pile reached a certain size, a chain reaction would start. By December 2, the size seemed to be right.
Enrico Fermi
Inside the pile were three control rods. They were made of cadmium, an element which soaks up flying neutrons like a sponge. With the rods in place, no reaction could take place. When the rods were withdrawn, the reaction would begin.
To make sure that the pile would not get out of hand, the three control rods were operated in three different ways. The first one was controlled by an electrical switch and was completely automatic. The second, called ZIP, was tied to a rope in the balcony. In case of emergency, there was a man ready with an axe. He had only to chop the rope and ZIP would go crashing back into the pile. The third rod was moved by hand.
It was time to begin. Fermi gave the signal for the automatic rod to be withdrawn. Immediately, the counters which measured radioactivity began to tick.