Search results for "Nuclear and High Energy Physics"
showing 10 items of 8241 documents
RBS and ERD cross-sections and optical model parameters for the analysis of lithium, boron and nickel
2000
Abstract Elastic scattering cross-sections for RBS analysis of nickel by 7 Li and 11 B ion backscattering near the Coulomb barrier have been determined. The lithium ion measurements were performed in the energy range of 8–15 MeV at the laboratory angles of 115° and 135°. For boron ions the energies between 14 and 24 MeV and scattering angles of 89°, 110° and 130° were used. For the analysis of lithium and boron by ERD the scattering cross-sections have been calculated by kinematically reversing the backscattering process. The calculated 58 Ni ion energies thus varied between 65 and 125 MeV for lithium and between 75 and 130 MeV for boron recoils. For the Li + Ni and B + Ni systems the thres…
Luminescence of divalent lanthanide doped BaBrI single crystal under synchrotron radiation excitations
2020
Abstract Luminescence excitation spectra of BaBrI single crystals doped by divalent lanthanide ions are studied using synchrotron radiation excitations from the MAX IV 1.5 GeV storage ring. The energy of the edge and the formation of core cation exciton as well as the energy threshold of the multiplications of electronic excitations is found. It was clearly established the energy transfer from intrinsic luminescence centers to Sm2+ and Eu2+ ions.
Systematic and statistical uncertainties of the hilbert-transform based high-precision FID frequency extraction method.
2021
Abstract Pulsed nuclear magnetic resonance (NMR) is widely used in high-precision magnetic field measurements. The absolute value of the magnetic field is determined from the precession frequency of nuclear magnetic moments. The Hilbert transform is one of the methods that have been used to extract the phase function from the observed free induction decay (FID) signal and then its frequency. In this paper, a detailed implementation of a Hilbert-transform based FID frequency extraction method is described, and it is briefly compared with other commonly used frequency extraction methods. How artifacts and noise level in the FID signal affect the extracted phase function are derived analytical…
Study of the Secondary Electron Yield in Dielectrics Using Equivalent Circuital Models
2018
[EN] Secondary electron emission has an important role on the triggering of the multipactor effect; therefore, its study and characterization are essential in radio-frequency waveguide applications. In this paper, we propose a theoretical model, based on equivalent circuit models, to properly understand charging and discharging processes that occur in dielectric samples under electron irradiation for secondary electron emission characterization. Experimental results obtained for Pt, Si, GaS, and Teflon samples are presented to verify the accuracy of the proposed model. Good agreement between theory and experiments has been found.
Conceptual study of a heavy-ion-ERDA spectrometer for energies below 6 MeV
2017
Abstract Elastic recoil detection analysis (ERDA) is a well established technique and it offers unique capabilities in thin film analysis. Simultaneous detection and depth profiling of all elements, including hydrogen, is possible only with time-of-flight ERDA. Bragg ionization chambers or Δ E - E detectors can also be used to identify the recoiling element if sufficiently high energies are used. The chief limitations of time-of-flight ERDA are the beam induced sample damage and the requirement of a relatively large accelerator. In this paper we propose a detector setup, which could be used with 3 MeV to 6 MeV medium heavy beams from either a single ended accelerator (40Ar) or from a tandem…
Comparative study of the luminescence properties of macro- and nanocrystalline MgO using synchrotron radiation
2013
MgO nano-powder with an average crystallite size of nanoparticles ranging 10-15 nm was synthesized using the extractive-pyrolytic method and was studied by room temperature VUV spectroscopy under synchrotron radiation excitation. Comparative analysis of their luminescent properties with that of mac- rocrystalline powder analogues and an MgO single crystal, grown by the arc-fusion method, has been per- formed under excitation by pulsed VUV synchrotron radiation. Special attention was paid to VUV spectral range, which is not reachable with commonly used lamp and laser sources. A considerable blue shift of about 0.3 eV in the excitation spectra of 2.95 eV emission band, was revealed in nanocry…
Annealing behaviour of aluminium-implanted InP
2000
The annealing behaviour of aluminium has been studied in single-crystal InP implanted with 40 and 120 keV 27Al+ ions. The implantation doses were 1 x 1015 and 1 x 1016 cm-2. The aluminium concentration profiles were determined by two techniques, Secondary ion mass spectrometry (SIMS) and the nuclear resonance broadening technique (NRB) which was used for checking purposes. The usability of the SIMS technique for profiling Al rich layers was studied. Significant inconsistencies were observed in the SIMS profiles with the high dose implanted samples. The 120 keV, 1 x 1016 cm-2 implanted samples were subject to annealing in argon atmosphere in the temperature range 380–600°C. Redistribution an…
Creation and thermal annealing of structural defects in neutron-irradiated MgAl 2 O 4 single crystals
2018
Abstract Several novel hole-type defects (a hole localized at a regular oxygen ion near a negatively charged structural defect) have been revealed in fast neutron irradiated MgAl2O4 crystals using the EPR method. The pulse annealing of the EPR signal of these centers was compared to that of radiation induced optical absorption in the same crystals. Taking into account the determined models of V1, V2 and V22 paramagnetic centers, the tentative scenario of the thermal annealing process of neutron-induced defects (hole-type and complementary electron F-type ones) is proposed. In addition, one more paramagnetic hole center consisting of an Al|Mg as-grown antisite defect near an aluminum vacancy…
Atomic structure of manganese-doped yttrium orthoaluminate
2018
Abstract Using hybrid exchange-correlation functional within density functional theory we have performed first-principle total energy calculations of Mn-doped yttrium orthoaluminate (YAlO3). Its equilibrium atomic structure has been predicted through optimization of coordinates of all atoms using a supercell approach. In our research both Mn3+ and Mn2+ ions have been substituted for the host alumina atom at orthorhombic Pbnm unit cell of YAlO3. F-center has been implemented as charge-compensating defect in case, when Mn2+ dopant is under study. In this study we thoroughly analyze the atomic displacements in seven nearest to Mn ion coordination spheres. Insertion of isoelectronic substitutio…
Peculiarities of the diffusion-controlled radiation defect accumulation kinetics under high fluencies
2020
We are grateful to A. Lushchik and E. Shablonin for numerous and valuable discussions. This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 and 2019-2020 under grant agreement No 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission. The raw/processed data required to reproduce these findings cannot be shared at this time as the data also forms part of an ongoing study.