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123 results on '"Paneta, V."'

1. Electronic Stopping of Slow Protons in Oxides: Scaling Properties

Author

Roth, D., Bruckner, B., Undeutsch, G., Paneta, V., Mardare, A. I., McGahan, C. L., Dosmailov, M., Juaristi, J. I., Alducin, M., Pedarnig, J. D., Haglund, Jr., R. F., Primetzhofer, D., and Bauer, P.

Subjects
Condensed Matter - Materials Science
Abstract

Electronic stopping of slow protons in ZnO, VO2 (metal and semiconductor phases), HfO2, and Ta2O5 was investigated experimentally. As a comparison of the resulting stopping cross sections (SCS) to data for Al2O3 and SiO2 reveals, electronic stopping of slow protons does not correlate with electronic properties of the specific material such as band gap energies. Instead, the oxygen 2p states are decisive, as corroborated by density functional theory calculations of the electronic densities of states. Hence, at low ion velocities the SCS of an oxide primarily scales with its oxygen density.

Published
2017
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31. Determination and theoretical analysis of the differential cross sections of the 2H(d,p) reaction at energies and detection angles suitable for NRA (Nuclear Reaction Analysis)

Author

Paneta V., Axiotis M., Gastis P., Kokkoris M., Kontos A., Lagoyannis A., Mayer M., Misaelides P., Perdikakis G., and Vlastou R.

Subjects
Physics, QC1-999
Abstract

The accurate determination of deuteron depth profile presents a strong analytical challenge for all the principal IBA (Ion Beam Analysis) techniques. As far as NRA (Nuclear Reaction Analysis) is concerned, the 2H(d,p) reaction, seems to be a promising candidate, especially in the case of complex matrices, or for the study of deep-implanted deuteron layers. In the present work differential cross-section values for the 2H(d,p) reaction have been determined at 140°, 160° and 170°, for Ed,lab=900-1600 keV, with an energy step of 50 keV, using a well-characterized, thin C:D target deposited on a polished Si wafer. The experimental results were analyzed using the R-matrix calculations code AZURE.

Published
2014
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32. Determination of the 193Ir(n, 2n) reaction cross section and correction methodology for the 191Ir(n,$ \gamma$) contamination

Author

Kalamara, A., primary, Patronis, N., additional, Vlastou, R., additional, Kokkoris, M., additional, Chasapoglou, S., additional, Stamatopoulos, A., additional, Serris, M., additional, Paneta, V., additional, Axiotis, M., additional, Lagoyannis, A., additional, Harissopulos, S., additional, and Stamatelatos, I. E., additional

Published
2019
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38. Activation cross section for the (n,2n) reaction on 197Au

Author

Kalamara, A., primary, Serris, M., additional, Anastasiou, M., additional, Diakaki, M., additional, Kokkoris, M., additional, Patronis, N., additional, Paneta, V., additional, Axiotis, M., additional, Lagoyannis, A., additional, and Vlastou, R., additional

Published
2019
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41. Electronic stopping of slow protons in oxides: Scaling properties

Author

Swedish Foundation for Strategic Research, Ministerio de Economía y Competitividad (España), Eusko Jaurlaritza, Netherlands Organization for Scientific Research, National Science Foundation (US), Vanderbilt University, Universidad del País Vasco, Roth, D., Bruckner, B., Undeutsch, G., Paneta, V., Mardare, A. I., McGahan, C. L., Dosmailov, M., Juaristi Oliden, Joseba Iñaki, Alducin Ochoa, Maite, Pedarnig, J. D., Haglund, R. F., Primetzhofer, D., Bauer, P., Swedish Foundation for Strategic Research, Ministerio de Economía y Competitividad (España), Eusko Jaurlaritza, Netherlands Organization for Scientific Research, National Science Foundation (US), Vanderbilt University, Universidad del País Vasco, Roth, D., Bruckner, B., Undeutsch, G., Paneta, V., Mardare, A. I., McGahan, C. L., Dosmailov, M., Juaristi Oliden, Joseba Iñaki, Alducin Ochoa, Maite, Pedarnig, J. D., Haglund, R. F., Primetzhofer, D., and Bauer, P.

Abstract

Electronic stopping of slow protons in ZnO, VO2 (metal and semiconductor phases), HfO2, and Ta2O5 was investigated experimentally. As a comparison of the resulting stopping cross sections (SCS) to data for Al2O3 and SiO2 reveals, electronic stopping of slow protons does not correlate with electronic properties of the specific material such as band gap energies. Instead, the oxygen 2p states are decisive, as corroborated by density functional theory calculations of the electronic densities of states. Hence, at low ion velocities the SCS of an oxide primarily scales with its oxygen density.

Published
2017

42. Study of the 11B(p, p′γ)11B reaction for PIGE applications

Author

Preketes-Sigalas, K. Lagoyannis, A. Axiotis, M. Harissopulos, S. Kokkoris, M. Mertzimekis, T.J. Paneta, V. Provatas, G.

Abstract

The differential cross sections of the 2125 keV γ-ray, emitted by the 11B(p, p′γ)11B reaction were measured at six (6) angles and at proton energies from 2.5 to 5.0 MeV. The experimental setup consisted of three (3) 100% relative efficiency HPGe detectors placed on a motorized turntable. The comparison between the present measurements, which have an overall uncertainty of ∼8%, and previous ones from literature gives contradictory results. While there are large differences with previous differential cross-section measurements from literature, there is good agreement with previous thick-target yield ones. Additional thick-target measurements were performed in an effort to explain the observed discrepancies. © 2015 Elsevier B.V. All rights reserved.

Published
2016

43. Electronic Stopping of Slow Protons in Oxides: Scaling Properties

Author

Roth, D., primary, Bruckner, B., additional, Undeutsch, G., additional, Paneta, V., additional, Mardare, A. I., additional, McGahan, C. L., additional, Dosmailov, M., additional, Juaristi, J. I., additional, Alducin, M., additional, Pedarnig, J. D., additional, Haglund, R. F., additional, Primetzhofer, D., additional, and Bauer, P., additional

Published
2017
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46. Probing high-energy ion-implanted silicon by micro-Raman spectroscopy

Author

Kopsalis, I., Paneta, V., Kokkoris, M., Liarokapis, E., Erich, M., Petrović, S., Fazinić, Stjepko, and Tadić, Tonči

Subjects
silicon amorphization, phonon confinement, ion implantation, channeling, lattice distortions
Abstract

The effect of ion implantation (4MeV(12)C(2+), 5MeV(16)O(2+), and 8MeV(28)Si(2+)) on [110] silicon wafers in channeling and random orientation is investigated by micro-Raman spectroscopy. The profiles were measured using Scanning Electron Microscope (SEM) showing that the ions were penetrating deeper inside the wafer in the channeling case creating a 1-2 mu m wide strongly modified region and agreeing with the d-nuclear reaction analysis measurements. Micro-Raman spectroscopy was employed for the assessment of the lattice damage, probing the side surface of the cleaved wafers at submicron step. The phonon modifications show strong lattice distortions in zones parallel to the front surface of the wafers and at depths, which agree with the results of the characterization techniques. In these strongly damaged zones, there is a substantial reduction in the phonon intensity, a small shift in wavenumber position, and a large increase in the phonon width. On the basis of a modification of the phonon confinement model that takes under consideration the laser beam profile, the reduction in intensity of scattered light, and the nanocrystallite size distribution from the simulation of the lattice displacements, the main characteristics of the Raman spectra could be reproduced for the random C and O implantations. The results indicate that at a critical doping level, the induced defects and lattice distortions relax by breaking the silicon single crystal into nanocrystallites, thus creating the observed zones of strongly distorted lattice.

Published
2014

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