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Ernest Rutherford: Nuclear Physics


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Ernest Rutherford: Nuclear Physics

In 1919, Rutherford announced that in experiments begun two years earlier, he had artificially "split" the atom by bombarding normally stable nitrogen with alpha particles to create fast protons (hydrogen) and an isotope of oxygen. Shortly after this discovery, he accepted an offer to succeed Thomson as the Cavendish Professor of Physics at the University of Cambridge.

Over the next two decades, Rutherford either directly or indirectly set into motion many of the pivotal discoveries of nuclear physics.

In 1920, he predicted the existence of the neutron, an uncharged particle just slightly heavier than the proton. Because of the difficultly in physically detecting an uncharged particle, it was not until that 1932 that Rutherford's student at Cambridge, James Chadwick, would prove its existence.

After successfully lobbying the British government for funding in 1929, Rutherford oversaw John Cockcroft and Ernest T.S. Walton's development of one of the first high-energy particle accelerators, a linear accelerator used to bombard elements with artificially accelerated protons. The cyclotron, a circular accelerator, was developed about the same time in the United States by Ernest Lawrence.

Along with Chadwick and Charles Drummond Ellis, Rutherford published "Radiation from Radioactive Substances" in 1930. Later works by Rutherford include "The Artificial Transmutation of the Elements" (1933) and "The Newer Alchemy" (1937).

The first nuclear fusion reaction was created at Rutherford's Cambridge Lab, as announced in 1934 by Marcus Oliphant and Paul Harteck. They bombarded concentrated heavy water (deuterium) with deuterons to produced tritium and helium. This process would lead to the creation of the hydrogen bomb, first detonated in 1952.

Although Enrico Fermi unknowingly created atomic fission as early as 1934, fission was first detected in 1938 by Otto Hahn, one of Rutherford's former students at McGill University. Hahn's work was the precursor to the Manhattan Project atomic weapons program in the United States. Commercial fission power plants were introduced by the mid-1950s.

Rutherford himself anticipated neither the rapid development of nuclear weaponry nor nuclear power, as he was accustomed to the low-level radiation typified by the natural decay of heavy elements. It was not until physicist Leó Szilárd and others perfected means of instigating fission chain reactions that the vast energy of heavy elements could be released almost in an instant, instead of over millions of years.

J. Robert Oppenheimer, scientific director of the Manhattan Project, was one of Rutherford's students at Cambridge. Students and/or research associates of Rutherford to win the Nobel Prize include Chadwick, Cockcroft and Walton, Patrick M.S. Blackett, G.P. Thomson (J.J. Thomson's son), Edward V. Appleton, Francis W. Aston, and Cecil Powell.

In 1931, Rutherford was granted peerage as First Baron Rutherford of Nelson, New Zealand, and Cambridge, and become a member of the House of Lords, making his popular title Lord Rutherford.

He died on October 19, 1937 at the age of sixty-six, due to complications from a hernia. His ashes are interred in Westminster Abbey in London.

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By John Pearson



Source: Ernest Rutherford, 2006, p3, 1p


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