On 146 years ago today, on August 30, 1871 (the fifteenth day of the seventh lunar month), the New Zealand physicist Rutherford was born.
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Rutherford was New Zealand's greatest scientist, and he could be called one of the greatest experimental physicists of any time. His career almost coincided with the first great period of nuclear physics, and he made many contributions to the field and dominated it for a long time.
Rutherford was born on 30 August 1871 (146) in Nelson, New Zealand. He was the fourth of 12 children. He was educated at Cumberland College in Christchurch. In 1895, he was awarded a scholarship to enter the University of Cambridge in England.
Rutherford had already done some work on high-frequency magnetic fields in New Zealand, and after arriving in Cambridge, he was still working on this research under the direction of Thomson, and it was not until 1896 that he began to study the conductivity of χ-rays ionizing air.
In 1898 he moved to Canada as a professor at McGill University. One of the Oxford-trained chemists, Frederick Sodi, collaborated with him for the most productive 18 months, publishing nine important papers between October 1901 and April 1903, laying the foundation for rigorous research in radiology.
Rutherford's first major advance in 1899 was his demonstration that there were two completely different types of radiation, which he called α rays and β rays. α-ray transmission is small but produces a lot of ionization, while β rays have the same transmittance as χ rays, but the ionization capacity is very small. Rutherford spent another 10 years of careful experimentation, and together with Sody came up with a bold theory of atomic transmutation.
In 1900 Rutherford pointed out that the third type of radiation, which is not deflected in the magnetic field, is high-energy electromagnetic radiation, which he calls "γ rays".
Rutherford also began to study the radioactive element thorium, which, in addition to α, β, γ rays, also emitted a radioactive gas, which he called "emission gas." He noted that the jet gas decays at a specific rate in terms of activity, losing half of its activity during a fixed period (half-life). Rutherford and Sodi began actively studying compounds for thorium, pointing out that a more active substance, thoriumχ, existed. They finally learned that the jet gas was produced by thorium χ, and that thorium χ was produced from natural thorium. That is, there is a sequence in which one of the chemical elements is changing (transmutating) into other elements.
In 1905, Rutherford and Sodi published their theory of transmutation sequences. Rutherford later published a book called The New Alchemy, which Sodi continued, eventually introducing the concept of isotopes.
Rutherford turned his attention to the α radiation emitted in radioactive decay, proving that α radiation was composed of helium atoms that had lost two electrons. In 1907 he moved to the University of Manchester in England to continue his research on α radiation. In Manchester, Rutherford and Hans-Geiger invented the Geiger counter in 1908. It was also here that Geiger and Ernest Marsden studied the scattering of α particles through thin metal foils in 1910, following Rutherford's suggestion, and they probed them with a screen coated with zinc sulfide, emitting a brief flash of light (flicker) when the high-energy particles hit the screen.
Geiger and Marsden found that the vast majority of particles have only tiny deflections as they pass through the gold leaf, but a very small proportion (about 1 in 8,000) deflects a lot. Rutherford later described this as "the most astonishing event I've ever encountered in my life,...... It's as unbelievable as if you bombard a sheet of tissue paper with a 15-inch shell and the shell bounces back and hits you. To explain this result, Rutherford proposed an atomic model in 1911, stating that almost all mass is concentrated in a very small region, and that most regions of the atom are "empty space." This is the nuclear atom (although Rutherford did not use the term "nuclear" until 1912). He also proposed a theoretical formula for the number of particles scattered by a nucleus at different angles. The idea of nuclear atoms was further developed by Niles-Bohr.
During World War I, Rutherford used acoustic methods to detect submarines in the service of the Navy, and after the war, he went to the Cavendish Laboratory at the University of Cambridge in England as a Cavendish Chair Professor and Director of Physics.
In this laboratory in 1919, he made a third important discovery - artificial nuclear metamorphosis. According to some of Marsden's early experiments, a α particle source was installed in a cylinder that could be filled with different gases, and a small hole was opened at one end of the cylinder, covered with a metal sheet, and some atoms could escape through the metal sheet. The cylinder is filled with nitrogen to produce high-energy particles, which are hydrogen nuclei (i.e., protons). Rutherford pointed out that "under the strong action of colliding head-on with high-speed α particles, nitrogen atoms metamorphose, and the released hydrogen atoms are an integral part of the nitrogen nucleus." Rutherford succeeded in making the first transmutation. Rutherford and James Chadwick continued between 1920 and 1924 that when bombarded with α particles, most lighter elements emitted protons.
Rutherford's achievements in this field actually opened up a completely new discipline- nuclear physics.