Edwin McMillan facts for kids
Quick facts for kids
Edwin McMillan
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| Born |
Edwin Mattison McMillan
September 18, 1907 |
| Died | September 7, 1991 (aged 83) El Cerrito, California, U.S.
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| Nationality | American |
| Alma mater | California Institute of Technology Princeton University |
| Known for | Discovery of neptunium, the first transuranium element Synchrocyclotron |
| Awards | Nobel Prize in Chemistry (1951) Atoms for Peace Award (1963) National Medal of Science (1990) |
| Scientific career | |
| Fields | Chemistry |
| Institutions | University of California, Berkeley Berkeley Radiation Laboratory |
| Thesis | Deflection of a Beam of HCI Molecules in a Non-Homogeneous Electric Field (1933) |
| Doctoral advisor | Edward Condon |
Edwin Mattison McMillan (born September 18, 1907 – died September 7, 1991) was an American scientist. He is famous for being the first person to create a transuranium element. These are elements with an atomic number higher than uranium. The element he discovered was neptunium. For this important discovery, he shared the 1951 Nobel Prize in Chemistry with Glenn Seaborg.
Edwin McMillan studied at the California Institute of Technology and earned his PhD from Princeton University in 1933. He then joined the Berkeley Radiation Laboratory. There, he discovered special forms (called isotopes) of oxygen and beryllium. During World War II, he worked on important projects like microwave radar and sonar. He also joined the Manhattan Project in 1942. This was a secret effort to build the first atomic bombs. He helped set up the Los Alamos Laboratory where the bombs were designed.
After the war, McMillan helped invent the synchrotron with Vladimir Veksler. This is a type of particle accelerator. He returned to the Berkeley Radiation Laboratory to build these machines. He became the associate director of the lab in 1954. In 1958, he became the director after Ernest Lawrence passed away. He stayed in this role until he retired in 1973.
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Early Life and Education
Edwin McMillan was born in Redondo Beach, California, on September 18, 1907. His father was a doctor. His nephew, John Clauser, also became a famous scientist and won the Nobel Prize in Physics in 2022.
His family moved to Pasadena, California, when he was young. He went to school there and graduated from Pasadena High School in 1924. He then went to the California Institute of Technology (Caltech), which was close to his home. He earned his bachelor's degree in 1928 and his master's degree in 1929. Later, he received his PhD from Princeton University in 1933.
Working at Berkeley Laboratory
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In 1932, McMillan received a special fellowship that allowed him to study at any university he chose. He decided to join Ernest Lawrence at the University of California, Berkeley. Lawrence had just started the Berkeley Radiation Laboratory.
At first, McMillan tried to measure the magnetic properties of a proton. However, other scientists completed these measurements first. The main goal of the Radiation Laboratory was to develop the cyclotron. A cyclotron is a machine that speeds up tiny particles. McMillan was very good at building scientific tools, and he helped make the cyclotron better. He helped improve how the machine's magnetic field was adjusted.
Working with another scientist, M. Stanley Livingston, McMillan discovered oxygen-15. This is a special form of oxygen that gives off positrons (tiny particles). They made it by shooting particles at nitrogen gas. He also discovered the isotope beryllium-10 in 1940 with Samuel Ruben. This isotope was very hard to find because it takes a very long time to decay.
Discovering Neptunium
In 1939, scientists Otto Hahn and Fritz Strassmann discovered nuclear fission in uranium. This means they could split uranium atoms. After this, McMillan started his own experiments with uranium. He used the lab's cyclotron to shoot neutrons at uranium.
He found two new radioactive substances. One lasted about 2.3 days, and the other about 23 minutes. McMillan realized the short-lived one was a known isotope of uranium. But he thought the other one, lasting 2.3 days, might be a new, undiscovered element. It would have an atomic number of 93.
At first, he worked with Emilio Segrè. They thought the new element would act like rhenium. But they found it did not. They even wrote an article saying they had not found a new element.
However, McMillan realized they hadn't tested all the chemical reactions. He tried a new experiment. In May 1940, Philip Abelson visited Berkeley. He had also been trying to separate the 2.3-day substance. They worked together and found that this substance was different from all known elements. It was more like uranium.
They proved that this new radioactive substance came from the decay of uranium. This meant they had found a new element! They published their findings in May 1940. They decided to name the new element "neptunium." This was because uranium was named after the planet Uranus, and Neptune is the next planet in our solar system.
Soon after, McMillan left for war-related work. Glenn Seaborg continued this research and discovered the next transuranium element, plutonium. In 1951, McMillan and Seaborg shared the Nobel Prize in Chemistry for their discoveries.
World War II Work
McMillan's work was interrupted by World War II. In November 1940, he started working at the MIT Radiation Laboratory. There, he helped develop and test microwave radar for airplanes. In 1941, he tested the radar from a bomber plane. They showed it could detect a submarine's conning tower (the top part) underwater.
McMillan married Elsie Walford Blumer in June 1941. Her sister was married to Ernest Lawrence, McMillan's boss. Edwin and Elsie had three children.
In August 1941, McMillan joined the Navy Electronics Laboratory. He worked on a device that used sonar to create a visual image underwater. This was very difficult and didn't work well. However, he did create a sonar training device for submarine crews, which earned him a patent.
In September 1942, J. Robert Oppenheimer asked McMillan to join the Manhattan Project. This was the secret project to build atomic bombs. McMillan helped choose the site for the main research lab, which became the Los Alamos Laboratory in New Mexico. He helped design the lab buildings and recruited scientists like Richard Feynman.
McMillan became a leader in the effort to build a "gun-type" atomic bomb. This design used a gun to shoot one piece of uranium into another. He also became interested in the "implosion-type" bomb. This design used explosives to crush a core of plutonium. The implosion method was more complex, but it turned out to be necessary for plutonium bombs.
In 1944, scientists found that plutonium made in reactors had an isotope that caused it to split on its own. This made the "gun-type" design impractical for plutonium. So, the "gun-type" bomb was only used with uranium-235. McMillan remained in charge of this design, which became known as Little Boy. He also helped with the implosion bomb, which was successfully tested at the Trinity nuclear test on July 16, 1945.
Later Life and Legacy
After the war, in June 1945, McMillan returned to thinking about cyclotrons. These machines were getting bigger and bigger. He realized there was a more efficient way to speed up particles. He called his idea the "phase stability principle." This led to a new design called the "synchrotron." He later found out that another scientist, Vladimir Veksler, had already thought of this idea in 1944. McMillan and Veksler became friends and shared the Atoms for Peace Award in 1963 for their invention.
When McMillan returned to the Radiation Laboratory in September 1945, they tested his principle on an old cyclotron, and it worked! He became a full professor in 1946. In 1954, he became the associate director of the Radiation Laboratory. In 1958, after Ernest Lawrence died, McMillan became the director. He held this position until he retired in 1973. The lab was renamed the Lawrence Radiation Laboratory in 1958.
McMillan was elected to the National Academy of Sciences in 1947. He also served on important committees for the United States Atomic Energy Commission. After retiring from teaching in 1974, he worked at CERN in Europe for a year. He received the National Medal of Science in 1990, one of the highest honors for a scientist in the U.S.
Edwin McMillan passed away on September 7, 1991, at his home in El Cerrito, California. His Nobel Prize medal is now kept at the National Museum of American History in Washington DC.
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See also
In Spanish: Edwin Mattison McMillan para niños
