Corson, Dale

Emilio Gino Segre (1905-1989 Nobel Prize for physics 1959), together with Dale Raymond Corson ( 1914) and Kenneth Ross Mackenzie ( 1912) obtained the element in tiny amounts by bombardment of bismuth with alpha particles. Halogen with no stable isotope. 

Astatine - the atomic number is 85 and the chemical symbol is At. The name derives from the Greek astatos for unstable since it is an unstable element. It was first thought to have been discovered in nature in 1931 and was named alabamine. When it was determined that there are no stable nuclides of this element in nature, that claim was discarded. It was later shown that astatine had been synthesized by the physicists Dale R. Corson, K. R. Mackenzie and Emilio Segre at the University of California lab in Berkeley, California in 1940 who bombarded bismuth with alpha particles, in the reaction Bi ( He, 2n ) "At. Independently, a claim about finding some x-ray lines of astatine was the basis for claiming discovery of an element helvetium, which was made in Bern, Switzerland. However, the very short half-life precluded any chemical separation and identification. The longest half-life associated with this unstable element is 8.1 hour °At. 

Astatine At 1940 (Berkeley, California) Dale Corson, Kenneth Mackenzie (both American) and Emilio Segre (Italian-American) 257... 

In 1940, three chemists working at the University of California at Berkeley found evidence of element 85. Dale R. Corson, Kenneth R. Mackenzie, and Emilio Segre (1905-1989) found evidence of element 85 at the end of an experiment they were conducting with a cyclotron. A cyclotton is a particle accelerator, or atom smasher. In a cyclotron, small particles, such as protons, are made to travel at high speeds. The particles collide with atoms, causing the atoms to break apart into other elements. 

Dale R. Corson, Kenneth R. Mackenzie, and Emilio Segre discover... 

My colleagues in this astatine experiment were Dale R. Corson and K. R. MacKenzie, who were working in Berkeley at the time. 

The 60-inch cyclotron group at Berkeley Donald Cooksey, Dale R. Corson, Ernest O. Lawrence, Robert L. Thornton, John Backus, Winfield W. ( W. W ) Salisbury, Luis W Alvarez, and Edwin M. McMillan, 1939 (Lawrence Berkeley National Laboratory)... 

American physicists Emilio Segre, Dale Corson, and... 

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