Little Bits of History

Carbon Fourteen

Posted in History by patriciahysell on February 27, 2014
Sam Ruben working on the discovery of Carbon-14

Sam Ruben working on the discovery of Carbon-14

February 27, 1940: Scientists at the University of California Radiation Laboratory in Berkeley discover Carbon-14. The radioactive isotope of Carbon, also written 14C or radiocarbon contains 6 protons and 8 neutrons within the nucleus. It was first suggested to exist by Franz Kurie in 1934 and Martin Kamen and Sam Rubin located it on this date. There are three naturally occurring isotopes of carbon. Carbon-12 makes up 99% of the element, carbon-13 makes up about 1%, and trace amounts of carbon-14 exist. About one part per trillion of carbon in the atmosphere is carbon-14 or 0.0000000001%. It has a half life of 5,730±40 years. It decays into nitrogen-14 through beta decay.

Because of the rarity and the fairly constant decay rate, the substance forms the basis for radiocarbon or simply carbon dating. Willard Libby found the technique for estimating the age of organic materials up to about 58,000 to 62,000 years Before Present (BP) with Present defined at 1950 AD. When a plant or animal is alive, it carries on gas exchange with the local atmosphere. Once it dies, this no longer takes place and the carbon contained will start to decay with a fairly steady rate. In this manner, by comparing the known saturation of carbon-14 in the air and then comparing it to the carbon in the material, one can calculate how long it has been since the plant or animal was alive and breathing.

Martin Kamen was born in 1913 in Toronto to Russian immigrant parents and grew up in Chicago. After earning his PhD in physical chemistry, he took a research position under Ernest Lawrence in Berkeley where he worked without pay for six months until he was actually hired. In 1943, Kamen began working on the Manhattan Project but soon returned to Berkeley. He was fired in 1945 after being accused of leaking nuclear secrets to Russia. He finally was able to be hired to run the cyclotron program at the medical school of Washington University at St. Louis. He later was able to obtain two other teaching positions, one in Massachusetts and the other at San Diego. He retired in 1978 and died at the age of 89 of natural causes.

Sam Ruben’s childhood neighbor was Jack Dempsey and the young boy developed an interest in boxing and later played basketball in high school. The family lived in Berkeley and he took his degree there, earning his PhD in physical chemistry in 1938. He was hired immediately as an instructor. His work was based on discovering the workings of photosynthesis and with this, he and Kamen ended up discovering carbon-14. Because there was so little of the substance to be found, the work was tedious but the two scientists persevered. When Kemon left to work on the Manhattan Project, Ruben continued study of phosgene, a poisonous gas. Ruben was working in the lab when he was exposed to the gas and died the next day, September 28, 1943. He was 29-years-old.

You will die but the carbon will not; its career does not end with you. It will return to the soil, and there a plant may take it up again in time, sending it once more on a cycle of plant and animal life. – Jacob Bronowski

Men love to wonder, and that is the seed of science. – Ralph Waldo Emerson

Science is a way of thinking much more than it is a body of knowledge. – Carl Sagan

Your theory is crazy, but it’s not crazy enough to be true. – Niels Bohr

Also on this day: Party in New Orleans! – In 1827, Mardi Gras was celebrated in New Orleans for the first time.
Andersonville – In 1864, the Confederacy’s POW camp at Andersonville opened.
The Lord and the Luddites – In 1812, George Gordon Byron spoke out in the House of Lords.
Suffrage – In 1922, Leser V. Garnett was decided by the US Supreme Court.


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