Manhattan Project, Segr?s Group
Segr?s Group fromleft to right: Emilio Segr?s, Owen Chamberlain, Gustave Linenberger, Ann Kahn, John Miskel, Milton Kahn, John Jungerman, Martin Deutsch, Unknown, Clyde Wiegand, George Farwell, Ralph Nobles, Unknown, Unknown. Emilio Gino Segr? (February 1, 1905 - April 22, 1989) was an Italian-born, naturalized American, physicist and Nobel laureate in physics, who with Owen Chamberlain, discovered antiprotons, a sub-atomic antiparticle. Working with his graduate students - Owen Chamberlain, George Farwell, Gustave Linenberger and Clyde Wiegand - Segr? and two University of California chemists, Arthur Wahl and Joseph Kennedy, measured rates of spontaneous fission in natural uranium and plutonium in 1942 and 1943. The plutonium was made by the 60-inch Crocker medical cyclotron at the UC Radiation Laboratory by the bombardment of uranium-238 by deuterons, the ions of heavy-water (deuterium). Although the results with plutonium produced in the Crocker medical cyclotron were encouraging, several researchers suggested that plutonium produced in nuclear reactors by the bombardment of uranium-238 by neutrons might have an isotope, plutonium-240, that would be likely to fission spontaneously. If this were only 1 percent of the reactor-produced plutonium and it had a high-spontaneous fission rate, predetonation would be much more likely. To investigate the possibility of spontaneous fission in plutonium, Los Alamos Director J. Robert Oppenheimer invited Segr? and his group to move to Los Alamos to continue their experiments there. Because of the delicacy of their detectors, the group could not remain in the technical area around Ashley Pond, where most of the scientific activity of the Laboratory was concentrated. They sought a place far from disturbances that might upset their instruments and ended up in Pajarito Canyon, 14 miles away
