James+Chadwick

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//James Chadwick//

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//Early life://

James Chadwick was born on October 20th, 1891 as the first son to John Joseph and Anne Mary Knowles Chadwick, he was soon followed by his two younger brothers Harry and Hubert. Even as young boy Chadwick demonstrated great intelligence, he was offered his first scholarship to the Manchester Grammar school around the tender age of seven or eight. Though due to financial problems Chadwick was forced to decline the scholarship and instead attended the Central Grammar School for Boys, he would be offered at least two more before in his mid teens. At the age of sixteen he sat for two university scholarship examinations, and was offered both, though ultimately Chadwick chose to attend the Victoria University of Manchester where he studied for a full year before being offered another scholarship to study physics. Chadwick graduated from the Honor School of Physics in 1911 before beginning his tutelage under Professor Ernest Rutherford for the next two years in the Physical Laboratory in Manchester. There Chadwick worked on various radioactive problems, one in particular that Professor Rutherford assigned to final-year students that became the basis of his first paper that was published in 1912. After graduation Chadwick continued to use the method that he had developed for measuring gamma rays to measure the measure the absorption of gamma rays by various gases and liquids. These experiments became the basis for his second paper, gaining his Master of Science degree In 1912, the following year he recieved the 1851 Exhibition Scholarship which allowed him to move to Berlin and work at the Physikalisch Technische Reichsanstalt at Charlottenburg to study beta radiation under Professor H. Geiger. While there Chawick used Geiger's recently developed Geiger counter, which provided more accuracy than the earlier photographic techniques, with it he was able to demonstrate that beta radiation produced a continuous electromagnetic spectrum, and not discrete lines as had previously been thought.

//World War 1//

In 1914 during the start of World War 1 Chadwick was still in Germany interning at the Ruhleben intern camp where he was allowed to set up a pseudo labarotory and conduct scientific experiments using improvised materials such as 'radioactive toothpaste' that proposed a cure for illnesses. For four years Chadwick was held captive as a prisoner of war in Germany, he was released after the Armistice of Germany came into effect in 1918. After regaining his freedom Chadwick returned to his parents home in England where he once agian took up tutelage under his one time undergraduate professor Ernest Rutherford who now the head of the nuclear physics lab at Cambridge University. Rutherford oversaw Chadwick's PhD in 1921 before making him assistant director of the lab.

//Cambridge://



Chadwick continued to focus his research on radioactivity, while previously, in 1919, Rutherford's research had focused on the atom which led to his discovering the proton. Though both Chadwick and Rutherford, along with many other researchers, were quickly realizing that the proton was not the only particle in the nucleus. As they studied atomic disintegration they realized that the atomic number was continuously lower than that of the atomic mass. Considering that electrons have no mass it was obvious obvious that some key element other than protons was adding to the mass of the nucleus. One explanation that they proposed was that there were electrons and additional protons in the nucleus and that the protons still contributed their mass but their positive charge was canceled out by the negatively charged electrons. It was here that Rutherford first proposed the idea that there was a particle with mass but no charge, he called it a neutron and imagined it as a paired proton with an electron. Though it. Would still be many years before any evidence of this thery could be discovered.

//Discovery of the Neutron://



Chadwick took on other projects while keeping the theory of an extra element in an atom's nucleus I the back of his mind. He began mimicking the experiments of other researchers, particularly those of Frederic and Irene Joliot-Curie, who used a different method for tracking particle radiation. He repeated their process with the goal of looking for a neutral particle, he was able to determine that the neutron did exist and that its mass was about 0.1 percent more than the proton's, Chadwick had his rules published under the title of "Possible Existence of the Neutron" he used alpha particles to bomb beryllium. This produced radial, the alignment of rays from a central location, Chadwick then used this radial to bomb hydrogen and nitrogen thud producing the atomic nucleus of hydrogen and nitrogen. Chadwick then decided that the radial was not an alpha radial or it wouldn't have had the momentum to cause the proton to leave the atom. Instead Chadwick decided it had to be a neutral particle with a mass similar to a proton. The next experiment that Chadwick performed was measuring the speed of the nuclei of hydrogen and nitrogen he succeeded by computing the mass of the new particle produced ,then using the mass to compute velocity. Chadwick then smashed an alpha particle into beryllium, a metallic element. This then released radiation that was aimed into paraffin wax. The beryllium radiation hit the hydrogen atoms that were in the wax. Chadwick then took the wax into a detecting chamber and massive neutral particles were discovered. Chadwick named these particles neutrons.



//Later/Personal Life://



In 1925 Chadwick married Aileen Stewart-Brown of Liverpool, they went on to have twin daughters and live at Denbigh, North Wales. His hobbies include gardening and fishing.Chadwick remained at Cambridge University until 1935 when he was elected to the Lyon Jones Chair of Physics in the University of Liverpool. He then went on to work in the United States as Head of the British Mission attached to the Manhattan Project for the development of the atomic bomb from 1943-1946, before returning to England. In 1948 Chadwick retired from active physics and his position at Liverpool, over the following years he received many honors such as the Medal for Merit and the Pour le Mèrite. He was knighted in 1945 for his achievements in science before he died in his sleep on July 24, 1974.

//Distraction pages://

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( a discussion of TV programs that feature Nobel Prize winners )

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( The Knight Bachelor and the process of knighting an individual )

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( The basics of Nuclear Weapons)

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