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Ernest Rutherford

coiner of the terms alpha ray, beta ray, half-life, and proton

Ernest Rutherford

Ernest Rutherford was born in Nelson, New Zealand, on August 30, 1871, the fourth of twelve children born to James and Martha Thompson Rutherford. He spent his early years working on the family farm and attending local schools, and got his first science book at the age of 10. One of the experiments suggested by this book involved using the speed of sound to determine the distance to a firing cannon, which gave him the knowledge to surprise his family by estimating the distance to a lighting flash. This same experiment also inspired him to make a miniature cannon out of a hat peg, a marble and blasting powder. The cannon exploded, luckily without causing injury.

Early Research

In 1889 Rutherford won a scholarship to attend Canterbury College at the University of New Zealand, Wellington, from which he received his Bachelor of Arts in Pure Mathematics and Latin (both compulsory), Applied Mathematics, English, French, and Physics in 1892. After earning his Master of Arts in both Mathematics and Physical Science and then his Bachelor of Sciences in Geology and Chemistry, he stayed on for two years of research, during which he invented a new form of radio receiver. His thesis, Magnetization of Iron by High-Frequency Discharges, was published in 1894. His second paper, Magnetic Viscosity, was published in the Transactions of the New Zealand Institute (1896) and contains a description of a time-apparatus capable of measuring time intervals of a hundred-thousandth of a second.

In 1895 Rutherford won a scholarship to study and conduct research at the Cavendish Laboratory at Cambridge University in England, where his talents were quickly recognized by Professor J.J. Thomson. With Thomson's encouragement, he invented a detector for electromagnetic waves that could detect radio waves at half a mile. He also worked jointly with Thomson on the behaviour of the ions observed in gases which had been treated with X-rays, and, in 1897, on the mobility of ions in relation to the strength of the electric field, and on related topics such as the photoelectric effect. In 1898 he reported the existence of alpha and beta rays (terms he coined) in uranium radiation and indicated some of their properties.

McGill University

In 1898 Rutherford accepted the Macdonald Chair of Physics at McGill University in Montreal, Canada. With assistance from research assistant Harriet Brookes, Rutherford promptly discovered radon, a chemically unreactive but radioactive gas.

By 1900 Rutherford had become established enough in his career for him to consider marriage, so he returned to New Zealand long enough to propose to Mary Georgina Newton. The two were married in Christchurch on June 28, 1900, and the couple returned to Canada soon after. Their only child, Eileen, grew up to marry physicist R.H. Fowler.

Back at McGill, Rutherford, with assistance from young chemist Frederick Soddy, proved that some heavy atoms spontaneously decay into slightly lighter atoms, a phenomenon for which he coined the term "half-life," and it was this work which first brought him world attention. He was elected a Fellow of the Royal Society of Canada in 1900 and of London in 1903. His first book, Radioactivity, was published in 1904. In 1908 he was awarded the Nobel Prize in Chemistry "for his investigations into the disintegration of the elements and the chemistry of radioactive substances." In realising that lead was the final decay product of uranium, Rutherford proposed that a measure of their relative proportions and the rate of decay of uranium atoms would allow minerals to be dated and, subsequently, this technique placed a lower limit on the age of the formation of the Earth.

University of Manchester

In 1907 Rutherford became the Langworthy Professor of Physics at the University of Manchester, England, where he and Hans Geiger established a center to study radiation. In conjunction with Geiger, Rutherford continued his research on the properties of alpha rays, and that research led to development of the Geiger Counter. In 1910 his investigations into the scattering of alpha rays and the nature of the inner structure of the atom which caused such scattering led to his concept of the "nucleus." According to Rutherford, practically the whole mass of the atom and at the same time all positive charge of the atom is concentrated in a minute space at the center. In 1912 Niels Bohr joined him at Manchester and he adapted Rutherford's nuclear structure to Max Planck's quantum theory and so obtained a theory of atomic structure which, with later improvements, remains valid to this day. In 1913, together with H. G. Moseley, Rutherford used cathode rays to bombard atoms of various elements and showed that the inner structures correspond with a group of lines which characterize the elements. Each element could then be assigned an atomic number and, more important, the properties of each element could be defined by this number.

Knighted in 1914, Rutherford left his laboratory soon after onset of the First World War to help the British Admiralty with problems of submarine detection. This research resulted in his only patent, for a directional hydrophone; that patent was quickly assigned to the Admiralty. After the United States entered the war in 1917, Sir Rutherford led the delegation to transfer submarine detection knowledge to them. After returning to his laboratory, he became the first person to "split the atom" in a nuclear reaction between nitrogen and alpha particles, during which experiment he also discovered (and named) the proton.

Cavendish Laboratory

Rutherford became Director of the Cavendish Laboratory at Cambridge University in 1919, where he took on more supervision and less direct research as years went by. Under his leadership, the neutron was discovered by James Chadwick in 1932, and in the same year the first experiment to split the nucleus in a fully controlled manner was performed by students John Cockcroft and Ernest Walton. Rutherford was was appointed to the Order of Merit in 1925, and in 1931 he was created First Baron Rutherford of Nelson, New Zealand, and Cambridge. He remained active and working to the very end of his life, which came on October 19, 1937; his ashes were buried in the nave of Westminster Abbey, just west of Sir Isaac Newton's tomb and by that of Lord Kelvin.

SOURCES
A Science Odyssey www.pbs.org
Biography Channel www.biography.com
Rutherford, Scientist Supreme www.rutherford.org.nz

SEE ALSO
Geiger Counter
First World War
Isaac Newton

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This page was last updated on 10/24/2017.