Neolithic artifacts made of nephrite, □Ca2(Fe,Mg)5Si8O22(OH)2, are found at prehistoric settlements in Bulgaria. This study investigates these objects based on particle induced X‐ray emission using a scanning nuclear microprobe (micro‐PIXE technique). Seven nephrite artifacts from the Neolithic sites of Kovachevo, Bulgarchevo and Galabnik in southwest Bulgaria were analyzed to quantify their composition and to establish if a correlation exists between the distribution of major and trace elements, color, impurities, and texture. The nephrite artifacts are tremolite in composition, with a proposed ultrabasic origin. Based on the geochemical data obtained by micro‐PIXE, we divide the artifacts into Group 1 objects from the Kovachevo site and Group 2 objects from the Galabnik and Bulgarchevo sites. The analytical data and microprobe analyses are compared with geochemical data of nephrite from across the globe. The results are in a good agreement with previous electron microprobe and electron paramagnetic resonance (EPR) spectroscopy data. Our study provides a better understanding of the mineralogy and geochemistry of nephrite artifacts and helps to address questions regarding origin and the distribution of such materials in Bulgaria and other Balkan countries.

An approach is proposed, and its potentialities are studied, for single-sided gamma-ray in-depth sensing and tomography of dense opaque media. The approach is based on lidar (LIgth Detection And Ranging) principle or, in the present case, graydar (Gamma RAY Detection And Ranging) principle, that is, time-to-range resolved detection of the backscattering-due radiative returns from the probed object irradiated by pulsed gamma-photon pencil beams. The basic analysis and data processing delta-pulse single-scattering graydar equation is formulated by analogy with the lidar equation and is shown to be applicable, under some determinate conditions, to the problems of gamma-ray in-depth profiling of dense media. It is shown analytically and by computer simulations that the approach developed in the work would enable one, at large-enough but reasonable sensing photon fluxes and measurement time intervals, to determine with good controllable accuracy and resolution the location, the material content, and the mass density of different homogeneous ingredients inside the probed object as well as the mass (or electron) density distribution within one-material objects. This approach can be widely applied, e.g., for nondestructive material examination in industry and aviation, detection of landmines and explosives, investigating the constitution of archeological artifacts, etc.

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