Structural Studies of the Qarakhanid Dirham Using X-Ray Diffraction and Neutron Tomography Methods

Non-destructive structural studies of coins from the Uzundara Fortress using X-ray diffraction and neutron tomography

“…The diffraction reflections for the obverse and reverse of the Heliocles copper coin (Figure 2 • . The formation of tenorite may indicate the presence of the studied copper coin in dry sandy soils without long-term oxygen access [14], which, in principle, is typical for the sites of archaeological excavations of the Uzundara fortress. From the analysis of the X-ray diffraction data by the Rietveld method, the relative content of tenorite in the volume of the studied imitation of Heliocles coins was obtained.…”

“…At analysis the obtained 3D model of imitation of Heliocles coins it was clearly detected an uneven distribution of the neutron attenuation coefficient in the corresponding volume of the coin (Figure 3 a). A possible explanation for this may be a rather deep penetration of the patina into the volume of the coin [13,14]. To estimate the relative volumes of the patina phase inside the coin, the segmentation procedure [13] of 3D neutron data was performed, as a result of which areas with a higher neutron attenuation coefficient were distinguished from the entire volume of the 3D model, which corresponds to volumetric regions with an increased patina content.…”

“…Currently, active experimental research is being conducted on the coins discovered during excavations using both traditional research methods and modern methods of non-destructive structural diagnostics [9][10][11][12][13]. Such structural methods include the X-ray diffraction method [14,15], which makes it possible to obtain information about the phase composition of the investigated object, and the neutron imaging methods, which allows to obtain the spatial distribution of phase components in the volume of the studied coins [13,14,[16][17][18]. The neutron tomography method, due to the features of the neutron beam interaction while passing through the elements of the investigated object with different chemical compositions, thickness and density, makes it possible to obtain detailed information about the internal structure of metal coins [16,19] with a spatial resolution at the micron level [20], as well as to obtain a virtual three-dimensional model of the coin for further analysis.…”

Change lost: Corrosion of Roman copper alloy coins in changing and variable burial environments

“…X-ray and neutron and scans have been used to clean digitally corroded coin faces (e.g. Adriaens et al 2010, Nguyen et al 2011, Bude & Bigelow 2020, Abdurakhimov et al 2021, extract individual coins from a hoard stored in a clay pot (Miles et al 2016) or reconstruct coins from the impression they left on corrosion crust after fully vanishing (Warnett et al 2017). This allowed identification by an experienced numismatist of half of the coins scanned at the most.…”

“…This allowed identification by an experienced numismatist of half of the coins scanned at the most. Scans have also been used to investigate the spatial distribution of remaining alloy and corrosion products (Bozzini et al 2014, Kichanov et al 2017, Abdurakhimov et al 2021) and optimize physical restoration (Bozzini et al 2014) or reveal the manufacture of coins (e.g. Abramson et al 2018;Herringer et al 2018;Salvemini et al 2018).…”