Herb Anderson: Fermi told me at the time that the quickest way to the chain reaction and all its consequences was to make a chain reaction
and that could probably be done first and most easily by the techniques most familiar to him using natural uranium.
And so we launched on a career of trying first of all to see what neutrons were emitted, and in what number. And a great deal
of emphasis was placed on the quantitative aspects of the subject. The paper "The production of neutrons in uranium bombarded
by neutrons" by Anderson, Fermi and Hanstein, was submitted to the Physical Review one month after that, March 16, 1939, and then appeared in the April 15th issue. And this showed that indeed neutrons were
emitted and in fairly copious numbers, experiments were a little bit on the rough side, but one could conclude from that experiment
that one and a half neutrons were emitted from uranium for each thermal neutron that was absorbed by uranium, and that was
a very important number, and not really very far from what is now known to be the value of that number, about 1.33.
Experiments are also being done -- in fact they always seem to be about a week or so ahead of us -- by Joliot, Halban and
Kowarski, working in Paris under very difficult conditions, and at the same time, and going on in the same laboratory at Columbia,
Szilard had gotten together with Zinn, and they also carried out an experiment demonstrating the emission of fast neutrons
when uranium absorbed a thermal neutron.
