| 1. |
- Zhou, Yushan, et al.
(författare)
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Micro ion beam analysis for the erosion of beryllium marker tiles in a tokamak limiter
- 2019
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier BV. - 0168-583X .- 1872-9584. ; 450, s. 200-204
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Tidskriftsartikel (refereegranskat)abstract
- Beryllium limiter marker tiles were exposed to plasma in the Joint European Torus to diagnose the erosion of main chamber wall materials. A limiter marker tile consists of a beryllium coating layer (7-9 mu m) on the top of bulk beryllium, with a nickel interlayer (2-3 mu m) between them. The thickness variation of the beryllium coating layer, after exposure to plasma, could indicate the erosion measured by ion beam analysis with backscattering spectrometry. However, interpretations from broad beam backscattering spectra were limited by the non-uniform surface structures. Therefore, micro-ion beam analysis (mu-IBA) with 3 MeV proton beam for Elastic back scattering spectrometry (EBS) and PIXE was used to scan samples. The spot size was in the range of 3-10 mu m. Scanned areas were analysed with scanning electron microscopy (SEM) as well. Combining results from mu-IBA and SEM, we obtained local spectra from carefully chosen areas on which the surface structures were relatively uniform. Local spectra suggested that the scanned area (approximate to 600 mu m x 1200 mu m) contained regions with serious erosion with only 2-3 mu m coating beryllium left, regions with intact marker tile, and droplets with 90% beryllium. The nonuniform erosion, droplets mainly formed by beryllium, and the possible mixture of beryllium and nickel were the major reasons that confused interpretation from broad beam EBS.
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| 2. |
- Kalamara, A., et al.
(författare)
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Determination of the Ir-193(n, 2n) reaction cross section and correction methodology for the Ir-191(n, gamma) contamination
- 2019
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Ingår i: European Physical Journal A. - : SPRINGER. - 1434-6001 .- 1434-601X. ; 55:10
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Tidskriftsartikel (refereegranskat)abstract
- The cross section of the Ir-193(n, 2n)Ir-192 reaction has been determined by means of the activation technique, relative to the Al-27(n, alpha) and Au-197(n, 2n) reference reactions cross sections, at neutron beam energies ranging from 10 to 21 MeV. The quasi-monoenergetic neutron beams were produced at the 5.5 MV Tandem T11/25 Accelerator Laboratory of NCSR "Demokritos" via the H-2(d, n) and H-3(d, n) reactions. The induced gamma-ray activity of the irradiated target and reference foils was measured with high resolution HPGe detectors. In order to correct for the contribution of the Ir-191(n, gamma)Ir-192 reaction, which is open to low energy parasitic neutrons, a recently developed analysis method was implemented and it is presented in great detail. Furthermore, cross section theoretical calculations were carried out using the EMPIRE and TALYS codes over a wide energy range.
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| 3. |
- Kantre, Karim-Alexandros, et al.
(författare)
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Investigation of the energy loss of I in Au at energies below the Bragg peak
- 2019
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier BV. - 0168-583X .- 1872-9584. ; 450, s. 37-42
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Tidskriftsartikel (refereegranskat)abstract
- The energy loss of iodine in gold was investigated at energies below the Bragg peak. With the present work, the range of the available experimental data is extended to significantly lower energies, while the nuclear stopping power contribution is taken into account. Experiments were performed on thin film targets in reflection geometry. Electronic stopping cross sections were extracted by different approaches from experimental spectra. The obtained results have been compared to tabulated values from SRIM and previously published experimental data, where available. For all energies the obtained values are consistently higher than predicted by SRIM. Monte Carlo simulations (TRIM) have been performed to study path length distributions and the influence of nuclear stopping on the total energy loss. The results from the calculations indicate that the experimental geometry might be an important factor affecting the observed energy loss due to a selection of specific trajectories.
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| 4. |
- Kokkoris, M., et al.
(författare)
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Argon ions deeply implanted in silicon studied by Rutherford/Elastic Backscattering and Grazing Incidence X-ray Fluorescence spectroscopy
- 2019
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier BV. - 0168-583X .- 1872-9584. ; 450, s. 144-148
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Tidskriftsartikel (refereegranskat)abstract
- Synchrotron-radiation based techniques have recently emerged as serious competitors to traditional nuclear analytical ones, not only in the characterization of various materials, but also when the depth profiling of ultra thin surface layers is concerned. The main goal of the present work was to investigate the applicability of Grazing Incidence X-Ray Fluorescence (GIXRF) and Rutherford/Elastic Backscattering Spectrometry (RBS/EBS) techniques with respect to the accurate quantitative determination of the retained doses of Ar ions deep implanted in random direction of Si [1 1 1] polished crystalline wafers. RBS/EBS measurements with protons and deuterons were taken along with GIXRF ones, the results were compared and an attempt was made to explain the occurring similarities and differences, along with the advantages and weaknesses of each applied analytical technique.
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| 5. |
- Paneta, Valentina, et al.
(författare)
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Ion-beam based characterization of TiN back contact interlayers for CZTS(e), thin film solar cells
- 2019
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier BV. - 0168-583X .- 1872-9584. ; 450, s. 262-266
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Tidskriftsartikel (refereegranskat)abstract
- Time-of-Flight Elastic Recoil Detection Analysis (ToF-ERDA) and Time-of-Flight Medium-Energy Ion Scattering (ToF-MEIS) have been employed to investigate the potential of TiN thin films as intermediate layers on Mo back contact in CZTS(e) solar cells. TiN films of various thicknesses (20, 50 and 200 nm) were prepared with reactive DC magnetron sputtering and atomic layer deposition on Mo/SLG (soda-lime glass) substrates and annealed ex situ in either S or Se atmosphere. In situ annealing of the samples to different temperatures was also performed in the MEIS setup together with subsequent ToF-MEIS and ERDA analysis. The results of the sample and interlayer composition profiles, layer quality and thickness distributions are discussed in context with complementary experimental findings partially obtained previously by X-ray Photoelectron Spectroscopy (XPS), X-ray Diffraction (XRD), Scanning Electron Microscopy and Scanning Transmission Electron Microscopy- Electron Energy Loss Spectroscopy (STEM - EELS).
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| 6. |
- Sortica, Mauricio A., et al.
(författare)
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On the Z(1)-dependence of electronic stopping in TiN
- 2019
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Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- We present a thorough experimental study of electronic stopping of H, He, B, N, Ne and Al ions in TiN with the aim to learn about the energy loss mechanisms of slow ions. The energy loss was measured by means of time-of-flight medium-energy ion scattering. Thin films of TiN on silicon with a delta-layer of W at the TiN/Si interface were used as targets. We compare our results to non-linear density functional theory calculations, examining electron-hole pair excitations by screened ions in a free electron gas in the static limit, with a density equivalent to the expected value for TiN. These calculations predict oscillations in the electronic stopping power for increasing atomic number Z(1) of the projectile. An increasing discrepancy between our experimental results and predictions by theory for increasing Z(1) was observed. This observation can be attributed to contributions from energy loss channels different from electron-hole pair excitation in binary Coulomb collisions.
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