JAMES CHADWICK – THE DISCOVERER OF NEUTRON
The smallest unit of matter that has properties of a chemical element is what we call as atom. It is known to all of us that atom is composed of electrons, protons and neutrons. But did you know that neutrons are a very useful tool in various industries for the purpose of material analysis? Neutrons, the subatomic particles have no electric charge therfore they can penetrate materials more efficiently than X-rays. Neutrons can penetrate through materials upto several centimeters. Neutron scattering technique is widely used in the field of transportation, building, mining, medicine, engineering, food processing and scientific research. James Chadwick, an English physicist is credited for the discovery of neutron.
James Chadwick was born to John Joseph and Anne Mary Knowles on 20th october, 1891 in the small town of Bollingtown, England, UK. He was named James after his paternal grandfather. His father was a railway keeper and mother was a domestic servant. James was 11 years old when he won entry into prestigious Manchester Grammer School. But since his parents could not afford even a small amount of fee James had to go to Central Grammar School for boys. Mathematics and physics were his favourite subjects. He won a scholarship at the age of 16 which permitted him to enroll at the Victoria University of Manchester.
Chadwick wanted to pursue mathematics but he enrolled for physics as his major since he was interviwed by a physicist who assumed that he wanted to study physics. Chadwick, being shy person could not contradict him. He became interested in physics after attending Ernest Rutherford’s lecture on electromagnetism.
In the year 1908 Chadwick started his university and by 1911 he sucessufully graduated with first class honors in physics. When Chadwick was in the final year of his degree he started working in Ernest Rutherford laboratory on a research project. Rutherford won the nobel prize for chemistry in the year when Chadwick entered university. Three years at university had been financially very tough for Chadwick, he always skipped lunch because of the little money he had. After graduation he continued his work in Rutherford laboratory untill he was 21 and in the year 1912 he was awarded a masters degree in physics. In the same year Royal Commission for the Exhibition of 1851 awarded him with an 1851 Research Fellowship.
He earned a scholarship which enabled him to go to Hans Geiger’s laboratory in Berlin, Germany. Geiger is rememberd for the invention of Geiger counter device that is used to detect and measure radioactivity. While he was working in Germany he used the Geiger counter and demonstrated that beta radiation produced a continous spectrum and not discrete lines. The first World War which happened during his stay in Germany ended his fruitful research work and for next four years he had to stay in Ruhleben internment camp. During his stay there he developed permanent indigestion problem due o very bad living conditions and poor nutrition. Nevertheless he was able to do some experiments with some equipment provided to him by some of the sympathetic German Physicists.
After the World War I, Chadwick returned to England to resume his work with Rutherford who was in charge of Cavendish laboratory at Cambridge University. In the year 1921, Chadwick was awarded Ph.D for his thesis in atomic numbers and nuclear forces.
Chadwick continued his research work at the cavendish laboratory and became Assistant Director of Research to Rutherford in the year 1923. In the year 1935 Chadwick received the nobel prize for the discovery of neutron.
Before he was awarded the nobel prize in 1935 the University of Liverpool had offered him Lyon Jones Chair of Physics. He accepted the offer and started his new job a month before he heard that he won a nobel prize. He started a nuclear physics group at Liverpool. The group required a piece of equipment called the cyclotron. The university could not afford to buy it therefore Chadwick had partly funded for it using his nobel prize money.
During the first year of the World War II, 1939, the British Governement asked Chadwick to build an atomic bomb. He said it was possible but was not an easy task. Working conditions were very bad in Chadwicks laboratory, Liverpool. German Force frequently attacked the neighbourhood. Despite of these difficulties, by 1941, Chadwick and his group was able to discover that the critical mass of Uranium-235 for a nuclear detonation was about 8 kilograms.
In the year 1941 Chadwick wrote a summary report on the atomic bomb work carried in British Universities. This report was read by USA president, Roosevelt in the same year and the USA government funded millions of dollars for his research work. When Chadwick met the American representatives he told them that he was 90 percent sure that the bomb would work.
Chadwick travelled to USA in the year 1943 to see the Manhattan’s Project’s facilities. Other than the Manhattan Project’s Director, American Major General Leslie Groves and Major General Thomas Francis Farrell, Chadwick was the only person to enjoy the access to America’s research, data and productions plants for the bomb. In the year 1944 Chadwick, along with his family moved to Los Alamos, the main research centre for the Manhattan project. He attended the trinity nuclear tests that took place on July 16, 1945.
In the year 1945 British government designated him as “ Sir James Chadwick” for his contribution during the war and in 1946 he was awarded the medal of merit by the U.S government.
In the year 1925 Chadwick married Aileen Stewart-Brown who belonged to Liverpool. The couple had twin daughters who live in Northe Wales. Fishing and gardening were the hobbies of James Chadwick. He died on 24th of July , 1974. He was 82 when he passed away and he had a very peaceful death.