Subscribe free to our newsletters via your
. 24/7 Space News .




CARBON WORLDS
Iowa State physicists explain the long, useful lifetime of carbon-14
by Staff Writers
Ames, IA (SPX) May 31, 2011


Iowa State University physicists, left to right, Pieter Maris and James Vary have used supercomputing power to solve the puzzle of the long, slow decay of carbon-14. That long half-life makes carbon-14 a useful tool to determine the ages of skeletons and other artifacts. Photo by Bob Elbert.

The long, slow decay of carbon-14 allows archaeologists to accurately date the relics of history back to 60,000 years. And while the carbon dating technique is well known and understood (the ratio of carbon-14 to other carbon isotopes is measured to determine the age of objects containing the remnants of any living thing), the reason for carbon-14's slow decay has not been understood.

Why, exactly, does carbon-14 have a half-life of nearly 6,000 years while other light atomic nuclei have half-lives of minutes or seconds? (Half-life is the time it takes for the nuclei in a sample to decay to half the original amount.)

"This has been a very significant puzzle to nuclear physicists for several decades," said James Vary, an Iowa State University professor of physics and astronomy. "And the underlying reason turned out to be a fairly exotic one."

The reason involves the strong three-nucleon forces (a nucleon is either a neutron or a proton) within each carbon-14 nucleus. It's all about the simultaneous interactions among any three nucleons and the resulting influence on the decay of carbon-14. And it's no easy task to simulate those interactions.

In this case, it took about 30 million processor-hours on the Jaguar supercomputer at Oak Ridge National Laboratory in Tennessee. Jaguar has a peak performance of 2.3 quadrillion calculations per second, a speed that topped the list of the world's top 500 supercomputers when the carbon-14 simulations were run.

The research project's findings were recently published online by the journal Physical Review Letters.

Vary and Pieter Maris, an Iowa State research staff scientist in physics and astronomy, are the lead authors of the paper. Collaborating on the paper are Petr Navratil of TRIUMF (Canada's National Laboratory for Particle and Nuclear Physics in Vancouver) and the Lawrence Livermore National Laboratory in California; Erich Ormand of Lawrence Livermore National Lab; plus Hai Ah Nam and David Dean of Oak Ridge National Lab. The research was supported by contracts and grants from the U.S. Department of Energy Office of Science.

Vary, in explaining the findings, likes to remind people that two subatomic particles with different charges will attract each other. Particles with the same charges repel each other. Well, what happens when there are three particles interacting that's different from the simple addition of their interactions as pairs?

The strong three-nucleon interactions are complicated, but it turns out a lot happens to extend the decay of carbon 14 atoms.

"The whole story doesn't come together until you include the three-particle forces," said Vary. "The elusive three-nucleon forces contribute in a major way to this fact of life that carbon-14 lives so long."

Maris said the three-particle forces work together to cancel the effects of the pairwise forces governing the decay of carbon-14. As a result, the carbon-14 half-life is extended by many orders of magnitude. And that's why carbon-14 is a very useful tool for determining the age of objects.

To get that answer, Maris said researchers needed a billion-by-billion matrix and a computer capable of handling its 30 trillion non-zero elements. They also needed to develop a computer code capable of simulating the entire carbon-14 nucleus, including the roles of the three-nucleon forces.

Furthermore, they needed to perform the corresponding simulations for nitrogen-14, the daughter nucleus of the carbon-14 decay. And, they needed to figure out how the computer code could be scaled up for use on the Jaguar petascale supercomputer.

"It was six months of work pressed into three months of time," Maris said.

But it was enough for the nuclear physicists to explain the long half-life of carbon-14. And now they say there are more puzzles to solve:

"Everybody now knows about these three-nucleon forces," Vary said. "But what about four-nucleon forces? This does open the door for more study."

.


Related Links
Iowa State
Carbon Worlds - where graphite, diamond, amorphous, fullerenes meet






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News





CARBON WORLDS
New form of girl's best friend is lighter than ever
Livermore, CA (SPX) May 20, 2011
By combining high pressure with high temperature, Livermore researchers have created a nanocyrstalline diamond aerogel that could improve the optics for something as big as a telescope or as small as the lenses in eyeglasses. Aerogels are a class of materials that exhibit the lowest density, thermal conductivity, refractive index and sound velocity of any bulk solid. Aerogels are among the ... read more


CARBON WORLDS
Parts of moon interior as wet as Earth's upper mantle

NASA-Funded Scientists Make Watershed Lunar Discovery

Moon may have more water than believed: study

President Kennedy's Speech and America's Next Moonshot Moment

CARBON WORLDS
Opportunity Spies Outcrop Ahead

A mole to explore the interior of Mars

Mars Formed Rapidly into Runt of Planetary Litter

NASA's Spirit Rover Completes Mission on Mars

CARBON WORLDS
NASA and Hawaii Partner for Space Exploration

NASA is Making Hot, Way Cool

Paolos wild ride down from ISS onboard Soyuz TMA-20

ATV-4 to carry name Albert Einstein

CARBON WORLDS
China's Fengyun-3B satellite goes into official operation

Venezuela, China to launch satellite next year

Top Chinese scientists honored with naming of minor planets

China sees smooth preparation for launch of unmanned module

CARBON WORLDS
On-Orbit Orion MPCV Navigation System Tested During STS-134 Shuttle Mission

Final Endeavour spacewalk marks 1,000 hours of station EVAs

Fourth and Final Shuttle Astronaut Spacewalk Set

Astronauts test new exercises on space walk

CARBON WORLDS
Payload processing underway for ASTRA 1N

Cosmica Spacelines And XCOR Aerospace Tout Suborbital Payload Flight Opportunties

Should India Go Suborbital

ASTRA 1N delivered to French Guiana

CARBON WORLDS
Second Rocky World Makes Kepler-10 a Multi-Planet System

Kepler's Astounding Haul of Multiple-Planet Systems Just Keeps Growing

Bennett team discovers new class of extrasolar planets

Climate scientists reveal new candidate for first habitable exoplanet

CARBON WORLDS
Two new tablets unveiled ahead of top Asia IT fair

Hackers highlight Sony's need for new ideas

Jobs to unveil Apple software innovations

China to step up fight against plastic addiction




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement