New technique welcomes calcium-41 to radiometric dating

Context

Scientists have suggested using Calcium-41 for Radiometric Dating as an alternative to Carbon-14 for determining the age of fossilized bones and rocks.

Background

Since its invention in 1947, carbon dating has revolutionised many fields of science by allowing scientists to estimate the age of an organic material based on how much carbon-14 it contains.
However, carbon-14 has a half-life of 5,700 years, so the technique cannot determine the age of objects older than around 50,000 years.
In 1979, scientists suggested using calcium-41, with a half-life of 99,400 years..

Calcium-14

It is produced when cosmic rays from space smash into calcium atoms in the soil, and is found in the earth’s crust, opening the door to dating fossilised bones and rock.
When an organic entity is alive, its body keeps absorbing and losing carbon-14 atoms. When it dies, this process stops and the extant carbon-14 starts to decay away.
Using the difference between the relative abundance of these atoms in the body and the number that should have been there, researchers can estimate when the entity died.

Atom-Trap Trace Analysis (ATTA) technique

A significant early issue with carbon dating was to detect carbon-14 atoms, which occur once in around 1,012carbon atoms. Calcium-41 is rarer, occurring once in around 1,015calcium atoms.
In the new study, researchers have pitched a technique called atom-trap trace analysis (ATTA) as a solution.
ATTA is sensitive enough to spot these atoms; specific enough to not confuse them for other similar atoms and fits on a tabletop.
A sample is vaporised in an oven. The atoms in the vapour are laser-cooled and loaded into a cage made of light and magnetic fields.
In an atom, an electron in one orbital can transition to the next if it’s given a specific amount of energy; then it jumps back by releasing that energy.
In ATTA, a laser’s frequency is tuned such that it imparts the same energy as required for an electron transition in calcium-41. The electrons absorb and release this energy, revealing the presence of their atoms.
ATTA also avoids potassium-41 atoms, which are similar to calcium-41 atoms but lack the same electron transition.

Application of ATTA and Calcium-41

What's New