Simulation of the thermal mechanism in semiconductors under action of pulsed electromagnetic field

The paper presents a model taking into account the time character of heat localization and distribution in semiconductor devices unlike the classical Wunsch-Bell linear model describing the thermal mechanism of EM-radiation action on REA. The classification of action levels is given. The nonlinear model permitting to determine the time boundary of heat propagation in the semiconductor device is presented. In the time range t>tcr a uniform volumetric heating of the object takes place, and for t<tcr there is a heat localization in the range of energy release due to the lag of the heat dissipation process behind the energy input process. Taking this into account one determines the energy leading to irreversible results of action. The model allows one to determine the feeblest aspects of REA.В роботі, на відміну від класичної лінійної моделі Вунча-Белла, яка описує тепловий механізм впливу ЕМ-випромінювання на РЕА, пропонується модель, що враховує часовий характер локалізації та розповсюдження тепла в напівпровідникових пристроях. Дається класифікація рівнів впливу. Приводиться нелінійна модель, яка дозволяє враховувати часову межу розподілення тепла в напівпровідникових пристроях. В масштабі часу t>tкр має місце однорідний об’ємний розігрів об’єкту, а при t<tкр має місце локалізація тепла внаслідок запізнення процесу тепловідводу від процесу енерговводу в області енерговиділення. Виходячи з цього визначається енергія, що приводить до незворотних наслідків дії. Модель дозволяє визначити найбільш слабкі місця РЕА і дозволяє спростити експериментальні випробування елементної бази РЕА в цілому.В работе, в отличие от классической линейной модели Вунча-Белла, описывающей тепловой механизм влияния ЭМ-излучения на РЭА, предлагается модель, учитывающая временной характер локализации и распространения тепла в полупроводниковых приборах. Дается классификация уровней воздействия. Приводится нелинейная модель, которая позволяет определить временную границу распространения тепла в полупроводниковом приборе. В диапазоне времен t>tкр имеет место однородный объемный разогрев объекта, а при t<tкр происходит локализация тепла в области энерговыделения вследствие запаздывания процесса теплоотвода от процесса энерговвода. Исходя из этого, определяется энергия, приводящая к необратимым результатам воздействия. Модель позволяет определить наиболее слабые места РЭА и позволяет упростить экспериментальные испытания элементной базы и РЭА в целом

Generation UWB signal at energization of a helical antenna high-current REB

In operation the possibility of generation of UWB signal was researched at excitement of a helical antenna by a high-current relativistic bundle of nanosecond duration. The experiments were conducted on a high-current relativistic accelerator REB "Темр-А" with parameters: Eb ~ 0,5…1,0 МeV, Ib ~ 5…10 кА, duration of a ~15 nс., at the value of a leading edge ~ 1…2 nс. The calculation data of a helical antenna and parameters of a generated UWB signal are reduced.Исследовалась возможность генерации СШП-сигнала при возбуждении изолированной спиральной антенны сильноточным релятивистским пучком наносекундной длительности. Эксперименты проводились на сильноточном релятивистском ускорителе РЭП «Темп-А» с параметрами: Eb~ 0,5…1,0 МэВ, Ib~ 5…10 кА, длительность пучка ~15 нс, при величине переднего фронта ~ 1…2 нс. Приведены расчетные данные спиральной антенны и параметры генерируемого СШП-сигнала.Досліджувалася можливість генерації НШС-сигналу при збудженні спіральної антени потужнострумовим релятивістським пучком наносекундной тривалості. Експерименти проводилися на потужнострумовому релятивістському прискорювачі РЕП «Темп-А» з параметрами: Eb~ 0,5…1,0 МеВ, Ib~ 5…10 кА, тривалість пучка ~15 нс, при величині переднього фронту ~ 1…2 нс. Приведено розрахункові дані спіральної антени і параметри генеруємого НШС-сигнал

Peculiarities of electronic structure and composition in ultrasound milled silicon nanowires

The combined X-ray absorption and emission spectroscopy approach was applied for the detailed electronic structure and composition studies of silicon nanoparticles produced by the ultrasound milling of heavily and lowly doped Si nanowires formed by metal-assisted wet chemical etching. The ultrasoft X-ray emission spectroscopy and synchrotron based X-ray absorption near edges structure spectroscopy techniques were utilize to study the valence and conduction bands electronic structure together with developed surface phase composition qualitative analysis. Our achieved results based on the implemented surface sensitive techniques strongly suggest that nanoparticles under studies show a significant presence of the silicon suboxides depending on the pre-nature of initial Si wafers. The controlled variation of the Si nanoparticles surface composition and electronic structure, including band gap engineering, can open a new prospective for a wide range Si-based nanostructures application including the integration of such structures with organic or biological systems. © 202

Track reconstruction and matching between emulsion and silicon pixel detectors for the SHiP-charm experiment

In July 2018 an optimization run for the proposed charm cross section measurement for SHiP was performed at the CERN SPS. A heavy, moving target instrumented with nuclear emulsion films followed by a silicon pixel tracker was installed in front of the Goliath magnet at the H4 proton beam-line. Behind the magnet, scintillating-fibre, drift-tube and RPC detectors were placed. The purpose of this run was to validate the measurement's feasibility, to develop the required analysis tools and fine-tune the detector layout. In this paper, we present the track reconstruction in the pixel tracker and the track matching with the moving emulsion detector. The pixel detector performed as expected and it is shown that, after proper alignment, a vertex matching rate of 87% is achieved

Measurement of the muon flux from 400 GeV/c protons interacting in a thick molybdenum/tungsten target

The SHiP experiment is proposed to search for very weakly interacting particles beyond the Standard Model which are produced in a 400 GeV/c proton beam dump at the CERN SPS. About 1011 muons per spill will be produced in the dump. To design the experiment such that the muon-induced background is minimized, a precise knowledge of the muon spectrum is required. To validate the muon flux generated by our Pythia and GEANT4 based Monte Carlo simulation (FairShip), we have measured the muon flux emanating from a SHiP-like target at the SPS. This target, consisting of 13 interaction lengths of slabs of molybdenum and tungsten, followed by a 2.4 m iron hadron absorber was placed in the H4 400 GeV/c proton beam line. To identify muons and to measure the momentum spectrum, a spectrometer instrumented with drift tubes and a muon tagger were used. During a 3-week period a dataset for analysis corresponding to (3.27±0.07) × 1011 protons on target was recorded. This amounts to approximatively 1% of a SHiP spill

Investigating the fine structure of near edge X ray absorption in the molecular spectra of C60F18 adsorbed on a single nickel crystal

Angular dependences of the fine structure of near edge X ray absorption NEXAFS of carbon C1s spectra are obtained for a monolayer film of C60F18 polar molecules on a Ni 100 substrate. The fine structure and angular dependences of these spectra are interpreted using calculation data obtained by the density functional method upon fitting NEXAFS spectra by the set of trial functions. It is shown that during deposition, the dipole moment of molecules is oriented perpendicular to the surface and fluorine atoms are the ones closest to the surfac

Experimental observation of C60F18 molecules orientation onto nickel single crystal 100 surface

The angular dependence of near edge X ray absorption fine structure NEXAFS spectra has been obtained in the vicinity of carbon and fluorine 1s absorption edges in a monolayer film of polar fullerene fluoride C60F18 molecules on a Ni 100 substrate. The fine structure of the spectra has been identified according to experimental data via calculations based on the density functional theory, and the angular dependence of the spectra has been explained. The orientations of structural molecular fragments are determined from the angular dependence of the NEXAFS spectra. It is demonstrated that the electric dipole moment of a C60F18 molecule is oriented along the normal to the substrate surface with an accuracy of