Esteban Irribarra

Escuela Politécnica Nacional | EPN · Departamento de Física

Graphene has attracted special attention due to its mechanical and electrical properties. In this work, we describe the effects of sub-10 keV electron beam irradiation on the electrical conductivity of few-layer graphene films deposited on a glass substrate. The irradiation process was performed in vacuum at 10 –6 Torr for 30 min per sample. The su...

The first observation of Parametric X-ray Radiation (PXR) produced in a crystalline powder constituted of crystallites whose largest dimensions are of the order of some nanometers is reported. PXR was registered during the interaction of a 7 MeV electron beam with a platinum powder. The experimental results were compared with the kinematical theory...

Parametric X-ray radiation associated with the diffraction of virtual photons and the diffraction of X-rays described as the diffraction of real photons are studied experimentally. The diffracted radiation was generated by a 7 MeV beam of electrons and an X-ray tube respectively. Both diffraction mechanisms occur in a tungsten powder. The processes...

Parametric X-ray Radiation registered in the backward geometry is analysed. The main properties of the radia-tion for such geometry are discussed. The advantages of the backward geometry over other configurations regarding the intensity, the spectral width and the possibility to discriminate the contributions form different radiation mecha-nisms to...

Parametric X-ray radiation produced during the interaction of charged particles with polycrystals is regarded. A review of the existing theories, perspectives of application and performed experiments is presented. The evolution of experimental capabilities as well as the progress in the process comprehension is illustrated. The state of the art of...

Parametric X-ray Radiation (PXR) produced in powders has been observed for the first time. PXR spectra were measured under observation angles of 150 and 180 degrees during the interaction of relativistic 7 MeV electrons with a tungsten powder. All the PXR peaks that theoretically can be produced in the studied energy region were registered. The per...

The texture of polycrystalline foils of tungsten and nickel was studied using Parametric X-ray Radiation (PXR) generated by 7 MeV electrons. The PXR rocking curves from crystallographic planes (200) for tungsten and (220) for nickel were obtained. A comparison with similar measurements obtained using diffraction of broadband X-rays is presented. Th...

Текстура поликристаллической фольги вольфрама и никеля изучалась с использованием параметрического рентгеновского излучения (PXR), генерируемого электронами с энергией 7 МэВ. Получены кривые качания PXR из кристаллографических плоскостей (200) для вольфрама и (220) для никеля. Приведено сравнение с аналогичными измерениями, полученными с использова...

The Parametric X-Ray radiation (PXR) spectra and yield dependencies on the orientation angle are measured during the interaction of 7 MeV electrons with a tungsten textured polycrystalline foil for different observation angles. The effects of PXR spectral density increase and PXR yield orientation dependence broadening in the backward direction is...

The Röntgen-1 setup which is intended for use in investigating the spectral-angular characteristics of X-rays generated due to the interaction between a 7-MeV electron beam and substances, including different shaped surfaces, is described. The setup is distinguished by a low radiation background, enabling the determination of low-intensity radiatio...

The paper presents the results of a theoretical study and a mathematical model of radiation processes occurred during the grazing interaction of fast electrons with semi-infinite targets applied on a thin amorphous layer. The developed model considers Vavilov-Cherenkov and transition radiation mechanisms and predicts the possibility to enhance the...

The paper presents the results of a theoretical study and a mathematical model of radiation processes occurred during the grazing interaction of fast electrons with semi-infinite targets applied on a thin amorphous layer. The developed model considers Vavilov-Cherenkov and transition radiation mechanisms and predicts the possibility to enhance the...

A new possibility to expand the energy region of diffraction processes based on the interaction of relativistic charged particles with crystalline structures is presented. Diffracted photons related to parametric X-ray radiation produced by relativistic electrons are detected below the low energy threshold for the X-ray diffraction mechanism in cry...

A set of experiments to study the guiding of 10 keV electrons by tapered glass capillaries was performed. It is shown that the 10 keV electron beam can be tightly focused by the tapered macrocapillaries. The charge/discharge processes of the capillary inlet are shown and discussed. The guiding effect was obtained for 10 keV electrons by a tapered g...

For the first time a classical model was developed to describe quantitatively the dynamics of charge distribution formation on a planar dielectric surface during its irradiation by fast electrons at a grazing incidence. The dynamic effects of the mutual influence of the beam and the dielectric surface charge predicted by the developed model are in...

The collimated spectra of polarization bremsstrahlung (PB) produced by 7 MeV electrons in Al, Ni, Cu, Mo and W poly crystalline foils are measured and the angular dependences of the PB characteristics are studied. A comparison of the experimental results with theoretical predictions is performed. Polarization bremsstrahlung sensitivity to texture a...

The measurements of X-ray polarization’s bremsstrahlung in the back scattering geometry (PBBS) generated during the interaction of 7 MeV electrons with polycrystalline foils of copper and niobium were performed. The analysis has shown a good agreement of the spectral width and position of the peaks with the theoretical calculations. The obtained re...

This paper contains the tension analysis of a new composite material based on a mixture of polyester resin reinforced by vegetal fiber, and its comparison with the pure polyester resin tension resistance. The analysis was made on mixtures with fiber weight percent of 5, 12, 15, and 20; the specimens were built using a cold compress process; and AST...

Study of 10 keV electron beam reflection from a single planar dielectric surface was made. Guiding effect for some part of the beam was observed within grazing angles of incidence. Ionization, electron emission and drain of the surface charge were considered in the computer model to explain the results.

The spectra of polarization bremsstrahlung are measured in the backscattering geometry during the interaction of 7-MeV electrons with a polycrystalline Ni foil. Measurement is conducted under conditions such that the size of the region of coherent X-ray radiation scattering in a target is on the order of 10 nm. The obtained results make it possible...

The spectrum of polarization Bremsstrahlung is measured in backscattering geometry for 7-MeV electrons and a polycrystalline Ni foil without texture. The average size of grains in the foil is 300 nm. The results show the possibility of using a new method in the diagnostics of the atomic structure of polycrystalline materials with nanosized grains....

The effect of the contactless transmission (guiding) of 10 keV electrons through cylindrical dielectric channels and planar channels formed by glass plates is studied. The capture and propagation of an electron beam along the channel axis, usual in these cases, are observed in the experiments with two plates. The deviation of the reflection angle f...

The paper is devoted to theoretical and experimental studies of the new approach to X-ray diagnostics of mosaic crystals being proposed. The model of the scattering process on the crystals with the arbitrary distribution function of the crystalline grains over orientation angles is considered in detail. Experimental setup created on the base of thi...