The Tamil Nadu State Department of Archaeology (TNSDA) has sent 23 charcoal samples from seven archaeological sites in Tamil Nadu to a lab in the United States for scientific dating.

• The testing method used is called AMS dating (Accelerator Mass Spectrometry), which is a very accurate way to find the exact age of old materials like charcoal.

Key Excavation Findings

• Keeladi (10th phase): Over 500 antiquities and 100 inscribed potsherds, including red-slipped ware with fish motifs.
• Porpanaikkottai (2nd phase): 11 trenches yielded 1,792 antiquities, including pottery, glass beads, and bangles.
• Tirumalapuram: A stone slab chamber with urn burials was excavated—first time in Tamil Nadu at a megalithic burial ground.

About Accelerator Mass Spectrometry (AMS)

• AMS is an advanced form of radiocarbon dating that directly counts carbon-14 atoms using a particle accelerator. 
• It requires very small samples and provides faster, more accurate results than traditional methods. 
• AMS is widely used in archaeology, forensics, and environmental studies.

How AMS Works ? 

• A tiny amount of organic material (as little as 50 mg) is cleaned and converted into a form like graphite.
• The sample is bombarded with electrons to produce negatively charged carbon ions, including carbon-12 (^12C), carbon-13 (^13C), and radioactive carbon-14 (^14C).
• The ions are passed through a particle accelerator, which gives them very high speed and energy.
• Using magnetic and electric fields, ions are separated based on mass-to-charge ratio — isolating ^14C from ^12C and ^13C.
• The number of ^14C atoms is directly counted, allowing precise calculation of how much remains in the sample.

Why AMS is Better Than Traditional Radiocarbon Dating ?

• Requires much smaller sample sizes (milligrams vs grams).
• More accurate and sensitive, especially for very old or tiny samples.
• Faster results, as it directly counts atoms instead of waiting for radioactive decay.
• Can distinguish carbon-14 from other similar isotopes, reducing errors.
• Suitable for precious, rare, or degraded samples (e.g. ancient texts, single seeds, bone fragments).
• Less affected by background radiation due to advanced shielding and filtering.

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