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The samples were analyzed by means of annihilation line Doppler broadening (DB) spectrometry using variable positron energy at the Dzhelepov Laboratory of Nuclear Problems, JINR in Dubna, Russia. A monoenergetic positron beam 4 mm in diameter was used; the positron energy varied from 0.1 keV to 22 keV. Annihilation γ radiation was recorded by the HPGe detector model GEM25P4-70 (AMETEK ORTEC, Oak Ridge, TN, USA) with an energy resolution of 1.20 keV, interpolated for an energy of 511 keV. The obtained DB spectra were analyzed by estimating the parameters S and W of the annihilation line, as well as graphical representation of the R parameter as a function of S = f(W). The study of the radiation resistance of thin films was carried out by irradiation with helium ions in the low-energy channel of the DC-60 ion accelerator (channel of the electron-cyclotron resonance source) up to an ion fluence of 2·1017 ion/cm2. During irradiation, the temperature of the samples did not exceed 200 °C. A layer-by-layer analysis of positron annihilation in Zr/Nb NMCs shows that irradiation by He+ ions with dose 2·1017 ion/cm2 leads to the formation of stable radiation defects. Once the energy reaches 20 keV, the probability of positron annihilation in the monocrystalline silicon substrate increases [1,2].
The research was supported by a grant from the Russian Science Foundation (project no. 20-79-10343).
[1] Laptev, R., Stepanova, E., Pushilina, N., Svyatkin, L., Krotkevich, D., Lomygin, A., Ognev S., Seimek K., Doroshkevich A., Uglov, V. Distribution of Hydrogen and Defects in the Zr/Nb Nanoscale Multilayer Coatings after Proton Irradiation. Materials, 15(9), 3332 (2022).
[2] Laptev, R., Lomygin, A., Krotkevich, D., Syrtanov, M., Kashkarov, E., Bordulev, Y., Seimek K., Kobets, A. Effect of Proton Irradiation on the Defect Evolution of Zr/Nb Nanoscale Multilayers. Metals, 10(4), 535, (2020).
