Limitation: Carbon14 dating can’t decide the age of objects older than round 50,000 years
Since its invention in 1947, carbon dating has revolutionised many fields of science by permitting scientists to estimate the age of an natural materials primarily based on how a lot carbon-14 it comprises. However, carbon-14 has a half-life of 5,700 years, so the technique can’t decide the age of objects older than round 50,000 years.
Calcium-41
In 1979, scientists steered utilizing calcium-41, with a half-life of 99,400 years.. It is produced when cosmic rays from area smash into calcium atoms within the soil, and is discovered within the earth’s crust, opening the door to dating fossilised bones and rock. But a number of issues want to be overcome earlier than it may be used to reliably date objects.
One necessary development was reported in Nature Physics in March 2023.
When an natural entity is alive, its physique retains absorbing and dropping carbon-14 atoms. When it dies, this course of stops and the extant carbon-14 begins to decay away. Using the distinction between the relative abundance of those atoms within the physique and the quantity that ought to have been there, researchers can estimate when the entity died.
A major early difficulty with carbon dating was to detect carbon-14 atoms, which happen as soon as in round 1,012 carbon atoms. Calcium-41 is rarer, occurring as soon as in round 1,015 calcium atoms.
In the brand new examine, researchers on the University of Science and Technology of China (USTC), Hefei, pitched a technique known as atom-trap hint evaluation (ATTA) as an answer. ATTA is delicate sufficient to spot these atoms; particular sufficient to not confuse them for different comparable atoms and suits on a tabletop.
A pattern is vaporised in an oven. The atoms within the vapour are laser-cooled and loaded right into a cage made of sunshine and magnetic fields. In an atom, an electron in a single orbital can transition to the following if it’s given a certain amount of power; then it jumps again by releasing that power.
Electron transition
In ATTA, a laser’s frequency is tuned such that it imparts the identical power as required for an electron transition in calcium-41. The electrons take in and launch this power, revealing the presence of their atoms.
The researchers reported having the ability to spot one calcium-41 atom in each 1,016 calcium atoms with 12% precision in seawater.
“However, there was only one sample analysed,” Tian Xia, an affiliate scientist on the USTC and a co-author of the paper, instructed The Hindu by electronic mail.
In future, “we hope that from the effusive atomic beam, the loading efficiency of the Ca-41 atoms into the trap can be improved,” in order that the measurement time for every pattern is decrease and the sensitivity is larger, Dr. Xia added.
His group chief, Zheng-Tian Lu, stated within the journal, Physics Today, that ATTA’s success is due to improvements with lasers: “laser power is a lot higher, and laser frequency control is better”.
ATTA additionally avoids potassium-41 atoms, that are comparable to calcium-41 atoms however lack the identical electron transition.
Earth-science utility
The researchers are at present exploring an earth-science utility. In hotter local weather, glaciers retreat and permit rock under to accumulate calcium-41. In colder local weather, glaciers advance and block the calcium-41 from reaching the rock.
This approach, scientists hope to use ATTA to examine how lengthy some rock has been lined by ice.
“We are collaborating with geo-scientists… by measuring the Ca-41 abundance in some rock samples,” Dr. Xia stated.
