Anderson, Herbert

Anderson, Herbert L., et al. 1939a The fission of uranium. Phys. Rev. 55 511. 

Bethe, H. A., and Bodansky, D. (1989). Energy Supply. In A Physicist s Desk Reference, ed. Herbert L. Anderson. New York American Institute of Physics. 

The same day Fermi stepped into the office of John R. Dunning, a Columbia experimentalist whose specialty was neutrons, to propose an experiment. Dunning, his graduate student Herbert Anderson and others at Columbia had built a small cyclotron in the basement of Pupin Hall, the modem thirteen-story physics tower that faces downtown Manhattan from behind the library on the upper campus. A cyclotron was a potent source of neutrons the two men talked about using it to perform an experiment similar to Frisch s experiment of January 13-14, of which they were as yet unaware. They discussed arrangements over lunch at the Columbia faculty club and afterward back at Pupin. 

While Fermi was away from his desk Bohr arrived to tell him what he already knew. Finding an empty office, Bohr took the elevator to the basement, to the cyclotron area, where he turned up Herbert Anderson ... 

Herbert Anderson returned to the basement of Pupin Hall that evening. He retrieved his neutron source. He calculated how many alpha particles the uranium oxide coated on a metal plate inside his ionization chamber would eject spontaneously in its normal process of radioactive... 

The important point for Dunning, the reason for his passion, was that if U235 was responsible for slow-neutron fission, then its fission cross section must be 139 times as large as the slow-neutron fission cross section of natural uranium, since it was present in the natural substance to the extent of only one part in 140. By separating the 235 isotope, Herbert Anderson emphasizes in a memoir, it would be much easier to obtain the chain reaction. More than this, with the separated isotope the prospect for a bomb with unprecedented explosive power would be very great. ... 

Now that the 6,000 had been paid, Columbia was able to buy the graphite Szilard had tracked down for Fermi s use. Cartons of carefully-wrapped graphite bricks began to arrive at the Pupin Laboratory, Herbert Anderson remembers, four tons in all. Fermi returned to the chain reaction problem with enthusiasm. This was the kind of physics he liked best Together we stacked the graphite bricks in a neat pile. We cut narrow slots in some of the bricks for the rhodium foil detectors we wanted to insert, and soon we were ready to make measurements. ... 

The demands of the implosion crisis in the autumn of 1944 reduced Trinity s priority, says Bainbridge, almost to zero. .. until the end of February 1945. With bomb physics well in hand by then Oppenheimer set the test shot s target date at July 4 and Bainbridge got busy. His staff of twenty-five increased across the next five months to more than 250. Herbert Anderson, P. B. Moon, Emilio Segr6 and Robert Wilson carried major re-... 

Herbert Anderson at Columbia first demonstrated nuclear fission in the United States in January 1939. 

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