Milestones, Sep. 8, 1975

Died. John Ray Dunning, 67, pioneering American nuclear physicist; of a heart attack; in Key Biscayne, Fla. Dunning directed the 1939 experiment at Columbia University's cyclotron in Manhattan that confirmed the findings of scientists in Germany and elsewhere about the possibility of controlled atomic fission. "Believe we have observed new phenomenon of far-reaching consequences," he scrawled in a diary. Dunning's later research showed that Uranium 235 was the most fissionable isotope, a discovery that led to the gas-diffusion method of refining U-235, currently used in nuclear bombs and most atomic power plants....

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