Nondestructive Structural Studies of the Euthydemus I Coin and Fragments of Rings from the Uzundara Fortress Using Neutron Tomography

Abstract

The penetration of corrosion into the volume of the copper coin of Euthydemus I and the fragments of rings from the Uzundara fortress was studied by the methods of neutron radiography and tomography using a facility installed on the horizontal beamline of the WWR-SM nuclear reactor of the Institute of Nuclear Physics, Academy of Sciences of the Republic of Uzbekistan. Three-dimensional models of the studied archaeological objects were reconstructed, and the volume fractions of the initial metal and corrosive materials were calculated. A large number of pores and cavities were found inside the volume of the coin, which may indicate a violation or imperfection of the casting technology, as well as active chemical processes due to the interaction of the coin with the soil. X-ray diffraction studies have established the presence of phases of copper, cuprite Cu₂O, and nantokite CuCl on the surface of the Euthydemus I coin. According to neutron tomography data, the volume content of copper and corrosion products was determined to be 1469.93(2) and 169.04(2) mm³, respectively. The distribution of pores in the volume of the Euthydemus I coin by an equivalent diameter has also been established. Two rings were studied at the neutron radiography and tomography facility; the volume of the first ring was 1491.17(6) mm³, and the volume of a certain corrosion was 135.69(7) mm³. On the second ring, the corrosion volume was 373.67(3) mm³, which is 12.1% of the total ring volume.