How so scientist use radioactive decay to date fossils and


How scientists use radioactive dating to approximate a fossil s age

The strangest product catalog on earth belongs to the Isotope Business Office, which manages the sale of atomic isotopes produced at Department of Energy labs around the country. It's got your calcium, platinum, and titanium. Your ytterbium, your strontium-95, and of course uranium-785 and plutonium-789 (responsible for Hiroshima and Nagasaki). The precursor to plutonium- 788 is neptunium-787, a radioactive by-product of nuclear power plants. Oak Ridge gets its neptunium trucked in from Idaho National Laboratory in a powdery form called oxide. When it arrives, it's deposited via a dumbwaiter-like system in a shielded room called a hot cell. Some of the neptunium oxide will have already decayed into a more dangerous radioactive material called protactinium, so small quantities are moved into a separate hot cell plumbed for radioactive liquids, where scientists can do the chemistry needed to remove it. Then the liquid is poured through a column of silica glass beads, whose surface attracts protactinium.

How is radioactive dating used to determine the age of an

The remaining liquid is moved to a glove box. In the glove box, the neptunium is processed with a technique invented at Oak Ridge called modified direct denitration. The liquid solution is rotated in a heated kiln until it sifts out, again in a powdered oxide form. This powder is mixed with powdered aluminum and pressed into pellets the size of a 5/8-inch socket, which are loaded into aluminum rods—targets for Oak Ridge's experimental high flux isotope reactor (HFIR). The HFIR offers much higher flux—the rate at which targets are bombarded with neutrons—than the reactor of a nuclear power plant.

Once target rods are loaded into the reactor, they're bombarded for a period of three to twelve months. As neutrons collide with the targets, some of them are absorbed by neptunium atoms. That creates a new neptunium isotope, neptunium-788, which radioactively decays into plutonium. When irradiation is complete, the targets go back into a hot cell. The rods are dissolved with a caustic solution and the radioactive material inside, now 67 to 69 percent plutonium-788, is again dissolved in nitric acid.

Why do scientists use radioactive decay com

A process called solvent extraction isolates the plutonium and neptunium: Solvents are added to the solution that dissolve only those elements. Then scientists induce the solution to separate—like oil and water—so that they can remove the solvent that's bound to them. At this point, neptunium is separated and can be passed through the cycle again. The plutonium is purified through a process called ion exchange, which Oak Ridge is still refining—a key step to reaching the 6.

5-kilogram per year delivery goal. Fully refined, the plutonium powder is packed into stainless-steel canisters designed for transporting radioactive materials. Isotopes are different forms of an element that share the same chemical properties, but that differ in mass and the number of neutrons they contain. Common elements that possess isotopes include carbon, oxygen, hydrogen, and nitrogen. Each element has a specific identifier, like 'C' for carbon, while a number placed before it identifies the isotope (e.

G. 68C and 67C). Some elements have many isotopes, but there are two basic types: stable and unstable or radioactive. Stable isotopes do not change over time while radioactive isotopes decrease or decay over predictable periods.

To distinguish different isotopes from each other, scientists use special instruments called mass spectrometers. Isotopes are everywhere in the environment.

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