How lasers are helping calcium-41 break into radiometric dating

Source: The post is based on the article “How lasers are helping calcium-41 break into radiometric dating” published in The Hindu on 23rd May 2023

What is the News?

A study has shown that Calcium-41 can be used the same way as Carbon-14 in carbon dating but with several advantages.

What is Radiometric Dating?

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’ve been there, researchers can estimate when the entity died. This process is called radiometric dating.

What is the drawback of using Carbon-14 for Radiometric Dating?

Carbon-14 – Radiocarbon (Carbon 14) is an isotope of the element carbon that is unstable and weakly radioactive.

It has a half-life of 5,700 years, so the technique can’t determine the age of objects older than around 50,000 years.

What is Calcium-41?

Calcium-41 is a rare long-lived radioisotope of calcium with a half-life of 99,400 years.

It is produced through cosmic ray interactions in the soil and is found in the Earth’s crust.

But the issue with Calcium-41 is that it occurs rarer, occurring once in around 10^15 Calcium atoms.

How did researchers overcome this drawback of Calcium-41?

Researchers at the University of Science and Technology of China pitched a technique called atom-trap trace analysis (ATTA) to spot these atoms.

ATTA is both extremely sensitive and selective and is based on laser manipulation and the detection of neutral atoms.

In this method, the sample is vaporized, and the atoms are laser-cooled and loaded into a light and magnetic field cage.

By tuning the laser’s frequency, Calcium-41 atoms can be detected through electron transitions.

What are the applications of Calcium-41?

Scientists are currently exploring Calcium-41 in earth-science applications. 

In warmer climates, glaciers retreat and allow rock below to accumulate calcium-41. In colder climates, glaciers advance and block the calcium-41 from reaching the rock. 

This way, scientists hope to use ATTA to study how long some rock has been covered by ice.