Персона: Вагнер, Вольфганг Зигфрид
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Институт нанотехнологий в электронике, спинтронике и фотонике
Институт ИНТЭЛ занимается научной деятельностью и подготовкой специалистов в области исследования физических принципов, проектирования и разработки технологий создания компонентной базы электроники гражданского и специального назначения, а также построения современных приборов на её основе.
Наша основная цель – это создание и развитие научно-образовательного центра мирового уровня в области наноструктурных материалов и устройств электроники, спинтроники, фотоники, а также создание эффективной инновационной среды в области СВЧ-электронной и радиационно-стойкой компонентной базы, источников ТГц излучения, ионно-кластерных технологий материалов.
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Вольфганг Зигфрид
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Теперь показываю 1 - 9 из 9
- ПубликацияТолько метаданныеSimulation of positron spectra of a hybrid positron source(2020) Wagner, W.; Savchenko, A. A.; Azadegan, B.; Вагнер, Вольфганг Зигфрид; Савченко, Александр АлексеевичAs known, the dipole approximation of channeling radiation (CR) successively overestimates the radiation yield, when the electron-beam energy approaches and exceeds 1 GeV. Consequently, we applied the nondipole approximation to simulate positron production via conversion of CR into e(+)e(-)-pairs in the scheme of a so-called hybrid positron source. GEANT4 simulations of positron spectra obtained from an amorphous tungsten converter at irradiation by <100> axial CR generated in tungsten and diamond single crystals are presented. For comparison, we calculated the CR spectra in dipole and nondipole approximation.
- ПубликацияТолько метаданныеNumerical and Monte Carlo study of positron production in a hybrid scheme based on 〈1 0 0〉 axial channeling radiation in a Si single crystal(2019) Mahdipour, S. A.; Azadegan, B.; Mowlavi, A. A.; Shafeei, M.; Wagner, W.; Вагнер, Вольфганг Зигфрид© 2019 Elsevier B.V.The non-conventional (hybrid) scheme of a positron source using GeV electron beams is investigated by means of our Mathematica and GEANT4 simulation codes. Axial channeling radiation (CR) is generated in a Si single crystal (radiator) and subsequently converted into e+–e− pairs in an amorphous tungsten (W) target (converter). We will present numerical calculations of axial CR spectra from relativistic electrons of different energies channeled in a Si single crystal. Applying both the dipole and non-dipole approach, comparison reveals a striking difference between obtained energy distributions of axial CR. Positron spectra obtained by pair production and captured by an adiabatic matching device (AMD) are simulated using GEANT4 toolkit. The AMD provides an axial magnetic field of upstream decreasing strength between the converter and the aperture of some pre-accelerating structure (linac). We also present Monte-Carlo simulation results of positron-beam emittance and transverse beam-density distribution behind the W converter and behind the AMD.
- ПубликацияТолько метаданныеNondipolarity of axial channeling radiation at GeV beam energies(2019) Azadegan, B.; Shafiee, M.; Wagner, W.; Savchenko, A. A.; Вагнер, Вольфганг Зигфрид; Савченко, Александр АлексеевичWe consider the nondipolarity of axial channeling radiation generated in a tungsten single crystal at electron-beam energies of several GeV. The calculations are based on the realistic axial continuous potential. It could be shown that, compared to the dipole approximation, the nondipole approximation results in a considerable variation of the channeling radiation spectrum. In a simulation of positron production via conversion of gamma radiation into e(+)e(-) pairs, the observed effect may play an important role.
- ПубликацияТолько метаданныеNew module for channeling radiation simulation in Geant4(2021) Savchenko, A. A.; Wagner, W.; Савченко, Александр Алексеевич; Вагнер, Вольфганг Зигфрид© 2021 IOP Publishing Ltd and Sissa MedialabWe present a new C++ module for simulation of channeling radiation to be implemented in Geant4 as a discrete physical process. The module allows simulation of channeling radiation from relativistic electrons and positrons with energies above 100 MeV for various types of single crystals. In this paper, we simulate planar channeling radiation applying the classical approach in the dipole approximation as a first attempt not yet considering other contributory processes. Simulation results are proved to be in a rather good agreement with experimental data.
- ПубликацияТолько метаданныеSimulation of channeling radiation and positron production in thick diamond structures and a tungsten single crystal(2019) Azadegan, B.; Wagner, W.; Savchenko, A. A.; Tishchenko, A. A.; Вагнер, Вольфганг Зигфрид; Савченко, Александр Алексеевич; Тищенко, Алексей Александрович© 2019 The process of de-channeling for electrons of energy 2 GeV channeled in the (110) plane of silicon and tungsten single crystals has been studied. The dynamics of the particle distribution density has been investigated in dependence on both the energy and scattering distribution of the initial electron beam. The influence of de-channeling on the spectral intensity of channeling radiation has been investigated by solving the Fokker-Planck equation. A non-conventional positron source is described based on the generation of radiation by relativistic electrons channeled along different crystallographic planes or axes of W, Si, Ge and C (diamond) single crystals and the subsequent conversion of the radiation into e+e−-pairs in an amorphous tungsten target. The simulation of channeling radiation and its dependence on the incidence angle into the crystal has been carried out by means of our Mathematica codes. The conversion of the radiation into e+e−-pairs and the energy distribution of positrons have been simulated using the GEANT4 package.
- ПубликацияТолько метаданныеGeant4 implementation of axial channeling radiation in classical description(2024) Savchenko, A. A.; Khudyakova, A. D.; Wagner, W.; Савченко, Александр Алексеевич; Худякова, Анна Дмитриевна; Вагнер, Вольфганг Зигфрид
- ПубликацияТолько метаданныеSpectral-angular distribution of radiation generated by a train of electron bunches passing through the centre of a ball(2024) Grigoryan, L. S.; Mkrtchyan, A. H.; Aleksandrov, P. A.; Wagner, W.; Вагнер, Вольфганг Зигфрид
- ПубликацияТолько метаданныеCauchy-like approximation of continuous crystal potential for axially channeled electrons(2025) Khudyakova, A. D.; Savchenko, A. A.; Wagner, W.; Худякова, Анна Дмитриевна; Савченко, Александр Алексеевич; Вагнер, Вольфганг Зигфрид
- ПубликацияТолько метаданныеDosimetric evaluation of neutron contamination caused by dental restorations during photon radiotherapy with a 15 MV Siemens Primus linear accelerator(2020) Ghorbani, M.; Azizi, M.; Azadegan, B.; Mowlavi, A. A.; Wagner, W.; Вагнер, Вольфганг Зигфрид© 2020 Elsevier LtdThe investigation of neutron contamination during radiotherapy by means of high-energy photon beams is a clinically important task. The present study aims to evaluate neutron contamination originating from the presence of various dental restorations, such as a tooth restored with amalgam, a tooth restored with Ni-Cr alloy, and a tooth restored with Ceramco. Using the MCNPX Monte Carlo code, we calculated the neutron contamination relative to the dose deposited in a water phantom at various penetration depths on the central axis of a photon beam provided by a 15 MV Siemens Primus linear accelerator operating in photon mode. Calculation of the energy spectrum of neutrons produced by the Siemens Primus linear accelerator revealed a peak at about 1 MeV. Dental restorations led to a maximum percentage neutron dose increase at a depth of 2.30 cm of 26.78%, 18.75%, and 10.71% for a tooth restored with amalgam, a tooth restored with Ceramco, and a tooth restored with Ni-Cr alloy, respectively, compared with 5.35% for a healthy tooth. Since the percentage neutron dose depends on the cross section of the photonuclear reaction with the restoration material and, hence, on the reaction energy threshold, underestimation of the dose in treatment planning may occur, especially if restoration materials of high atomic number are used. The fast-neutron equivalent dose for water decreases with increasing depth. For dental restorations with amalgam, Ceramco, and Ni-Cr alloy, it reaches maximum values beyond the dental phantom of 1.28, 1.15, and 0.94 mSv, respectively. The maximum values of the thermal-neutron equivalent dose beyond the dental phantom are 1.32, 1.23, and 1.16 mSv for amalgam, Ceramco, and Ni-Cr alloy, respectively.