Researchers from Israel have developed a new way to date archaeological objects that is based on superconductivity. The new technique relies on measuring the magnetic signal from lead–which was widely used in antiquity–in samples that have been cooled to cryogenic temperatures. The method could be used to date pipes, coins, bottles and other objects.

Lead is stable in many environments and corrodes only very slowly into lead oxide and lead carbonate. It becomes a superconductor when cooled below 7.2 Kel-vin, whe-reas the corrosion products do not. This means that the magnetization of the lead will be several orders of magnitude higher than that of the corrosion products when the sample is placed in an applied magnetic field at temperatures below 7.2 Kelvin. It is therefore reasonable to assume that the magnetic signal from the sample is coming from the lead only.

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