The knot is untied; the C-14 mystery is solved!

Author:  Ziadh Muhammed
Date:  February 2008

The knot that puzzled researchers for more than half a century has finally been untied. Stony Brook University researchers Gerald Brown and Jeremy Holt have finally come up with new calculations to verify the theory which explains the slow decaying characteristic of the radioactive isotope Carbon-14.

Isotopes are identical elements having different mass numbers. Most carbon in nature exists in the C-12 form (with atomic number 12). C-14 isotope is very valuable for archeologists. The age of a plant or animal fossil is calculated by analyzing the ratio of C-14 to N-14 in the organism. This ratio helps to determine when a sample took its last breath or photosynthesized.

The theory Brown-Rho scaling, proposed by physicists G.Brown and M.Rho of Stony Brook University in New York in 1990, explains why it takes 5730 years to decay 50% of C-14 isotope. (It is a fairly long time when compared to other isotopes.)

In the nucleus, the subatomic particle "Meson" keeps the nucleus in position with two strong nuclear forces namely the central force and the tensor force. The Brown-Rho scaling theory concludes that the two forces are nearly in balance in the case of C-14, thus, rendering it stable and relatively resistant to decay. However, in other isotopes, these forces are not in equilibrium, rendering the nucleus unstable and forcing the isotopes to decay within hours. Holt's team has proved this theory mathematically for the first time.

Holt's team said the main role player of the process is the sensitivity of C-14 decay to the tensor force. "This is the basic mechanism leading to the long lifetime we predict," Holt said.

Physicist Larry Zamick, pointed out that the findings further assert the connection between tensor force and C-14 decay, first discovered by Israeli physicist Igal Talmi in 1954. However, "Holt's calculations cover only certain meson interactions within the shell of the carbon nucleus," Zamick says. For this reason, he recommends the team to expand its conclusions to cover "a larger shell model."

Holt's findings and methodology will soon be released in an upcoming issue of Physical Review Letter.

Written by Muhammed Ziadh.

Reviewed by Yash Somnay, Pooja Ghatalia

Published by Pooja Ghatalia.