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0225U005192,
(0124U002466)
,
Application of X-ray phase contrast imaging and annihilation spectroscopy to study the defective structure of materials
Час життя позитронів в конструкційних матеріалах реакторів та прискорювачів з урахуванням локальних змін електронної густини
Lebed Oleksandr A., Доктор фізико-математичних наук
26-12-2025
Institute of Applied Physics National Academy of Sciences of Ukraine
Investigation of new physical regularities and features in the formation of X-ray phase contrast images of the defective structure of materials, in particular: near-surface layers of materials of accelerator tubes and irradiated materials for the needs of nuclear energy
Analytical approaches have been developed to calculate the positron lifetime in a material taking into account local changes in the electron density associated with its defect structure. A modified Tao-Eldrup model has been considered, which allows analytical calculation of the positron lifetime in a spherically symmetric potential well of finite height. In this case, the annihilation rate is determined by the overlap of the positron and electron densities due to tunneling through the boundaries of the potential well into the base material and into the well. The developed modified model provides important information for the analysis of the positron lifetime spectra in irradiated materials and data for verification of quantitative calculations of the positron lifetime by density functional methods, which are widely used for such problems. Using the ABINIT software package, the distribution of electron and positron densities near a vacancy was calculated using the example of multicomponent alloys that have prospects for widespread use in fourth-generation nuclear power. This in turn makes it possible to determine the shape and size of potential wells in such materials, which is necessary for predicting the results of experimental measurements and will be useful in analyzing data from studies of irradiated samples. The proposed research methods will be useful for optimizing material diagnostics, detecting and identifying defects, and non-destructive research of structural characteristics of objects of various nature.
Serhii O. Lebedynskyi
Mykhailo M. Diachenko
Lebed Oleksandr A.
Artur Ovcharenko
Vorona Maryna I.
2025-12-26
Updated: 2025-12-27
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