Why in news?
Archaeologists in Tamil Nadu sent samples of charcoal from an ancient site to foreign laboratories for accelerator mass spectrometry dating, seeking more precise timelines for early human settlements.
What is AMS dating?
- AMS dating is a sophisticated form of radiocarbon dating that measures isotopes directly using a particle accelerator. It detects rare carbon‑14 atoms relative to stable carbon‑12 and carbon‑13.
- It can date organic materials up to about 50,000 years old.
How it works
- Sample preparation: Organic remains (wood, charcoal, bone) are cleaned and converted into graphite.
- Ionisation and acceleration: The graphite is ionised to create negative ions that are accelerated through a high‑voltage field.
- Isotope separation: Magnetic and electrostatic fields separate isotopes by mass. Detectors count the number of carbon‑14 atoms.
- Age calculation: The ratio of carbon‑14 to carbon‑12 gives an estimate of the sample’s age when corrected for background radiation and calibration curves.
Advantages
- High precision: AMS can measure tiny samples with high accuracy, reducing statistical uncertainty.
- Small sample size: Only a few milligrams of material are needed, preserving valuable artefacts.
- Non‑destructive: The technique minimally damages the sample compared with conventional radiocarbon dating.
Applications
- Archaeology: Dating prehistoric sites, cave paintings, ancient boats and human remains.
- Geology and oceanography: Studying carbon cycles, sedimentation and palaeoclimate records.
- Biomedical science: Tracing drug metabolism, diet histories and cellular turnover.