Arsham Yeremyan - Academia.edu (original) (raw)
Papers by Arsham Yeremyan
Transverse emittance is one of the most important properties for high-brightness electron beams u... more Transverse emittance is one of the most important properties for high-brightness electron beams used for X-Ray free-electron lasers. The photo injector test facility at DESY in Zeuthen (PITZ) focuses on the development of high-brightness electron sources. The two main methods to measure the emittance are the quadrupole scan and the slit scan. Combining either of these methods with a transverse deflecting cavity allows the measurement of the slice emittance. At PITZ, space-charge effects at the low beam momentum of 24 MeV/c complicate in particular the quadrupole scan. This has to be considered in the emittance measurements. First slit-scan based slice emittance results will be shown next to studies on the beam transport for quadrupole scans.
In addition, the optical laboratories require a clean environment in order to avoid deposition of... more In addition, the optical laboratories require a clean environment in order to avoid deposition of dust on-and damage the optics. The laser laboratory is equipped with a conditioner with dust collecting filters. Nevertheless, the students are asked to wear the clean jacks and replacement shoes or polyethylene covers available at the entrance of the Laser room.
International Journal of Molecular Sciences, 2021
The development of new laser-driven electron linear accelerators, providing unique ultrashort pul... more The development of new laser-driven electron linear accelerators, providing unique ultrashort pulsed electron beams (UPEBs) with low repetition rates, opens new opportunities for radiotherapy and new fronts for radiobiological research in general. Considering the growing interest in the application of UPEBs in radiation biology and medicine, the aim of this study was to reveal the changes in immune system in response to low-energy laser-driven UPEB whole-body irradiation in rodents. Forty male albino Wistar rats were exposed to laser-driven UPEB irradiation, after which different immunological parameters were studied on the 1st, 3rd, 7th, 14th, and 28th day after irradiation. According to the results, this type of irradiation induces alterations in the rat immune system, particularly by increasing the production of pro- and anti-inflammatory cytokines and elevating the DNA damage rate. Moreover, such an immune response reaches its maximal levels on the third day after laser-driven U...
Journal of Electronic Materials, 2016
We present the results of a study on localized electronic centers formed in crystals by external ... more We present the results of a study on localized electronic centers formed in crystals by external influences (impurity introduction and irradiation). The main aim is to determine the nature of these centers in the forbidden gap of the energy states of the crystal lattice. For the case of semiconductors, silicon (Si) was applied as model material to determine the energy levels and concentration of radiation defects for application to both doped and other materials. This method relies on solving the appropriate equation describing the variation of the charge carrier concentration as a function of temperature n(T) for silicon crystals with two different energy levels and for a large set of N 1 , N 2 (concentrations of electronic centers at each level), and n values. A total of almost 500 such combinations were found. For silicon, energy level values of e 1 = 0.22 eV and e 2 = 0.34 eV were used for the forbidden gap (with corresponding slopes determined from experimental temperature-dependent Halleffect measurements) and compared with photoconductivity spectra. Additionally, it was shown that, for particular correlations among N 1 , N 2 , and n, curve slopes of e 1 /2 = 0.11 eV, e 2 /2 = 0.17 eV, and a = 1/2(e 1 + e 2) = 0.28 eV also apply. Comparison between experimental results for irradiation of silicon crystals by 3.5-MeV energy electrons and Co 60 c-quanta revealed that the n(T) curve slopes do not always coincide with the actual energy levels (electronic centers).
Frontiers in Optics 2016, 2016
We experimentally demonstrate solitonic self-spectral compression for noisy supercontinuum radiat... more We experimentally demonstrate solitonic self-spectral compression for noisy supercontinuum radiation in a single-mode fiber. The numerical modeling of the process shows the prospects of the noise nonlinear suppression for partially coherent pulses.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2016
The AREAL laser-driven RF gun provides 2-5 MeV energy ultrashort electron pulses for experimental... more The AREAL laser-driven RF gun provides 2-5 MeV energy ultrashort electron pulses for experimental study in life and materials sciences. We report the first experimental results of the AREAL beam application in the study of molecular-genetic effects, silicon-dielectric structures, ferroelectric nanofilms, and single crystals for scintillators.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2016
Advanced Research Electron Accelerator Laboratory (AREAL) is a 50 MeV electron linear accelerator... more Advanced Research Electron Accelerator Laboratory (AREAL) is a 50 MeV electron linear accelerator project with a laser driven RF gun being constructed at the CANDLE Synchrotron Research Institute. In addition to applications in life and materials sciences, the project aims as a test facility for advanced accelerator and radiation source concepts. In this paper, the AREAL RF photoinjector performance, the facility design considerations and its highlights in the fields of free electron laser, the study of new high frequency accelerating structures, the beam microbunching and wakefield acceleration concepts are presented.
Journal of Modern Physics, 2018
This paper reports results from an investigation of the interaction of displaced Si-self atoms (I... more This paper reports results from an investigation of the interaction of displaced Si-self atoms (I) and their vacancies (V), with impurities in crystalline silicon (Si), as induced by micro-second pulse duration irradiation with electrons at different energies: 3.5, 14, 25 and 50 MeV and pico-second pulse duration with energy 3.5 MeV. V-V, I-impurity atom and V-impurity atom interactions are analyzed both experimentally and as modeled using computer simulations. A process of divacancy (V 2) accumulation in the dose-dependent linear region is investigated. The effect of impurities on recombination of correlated divacancies, and I-atoms that had become displaced from regular lattice points is estimated by computer modeling of an appropriate diffusion-controlled process. It is concluded that the experimental results can be interpreted quantitatively in terms of a strongly anisotropic quasi-one-dimensional diffusion of displaced I-atoms. In addition, a significant difference is found between the effects of pico-second duration electron beam irradiation, which causes the formation of A-centre (V + Oxygen) clusters, while when the beam is applied on a micro-second timescale, divacancies are created instead, although the electrons have the same energy in both cases.
Advanced Research Electron Accelerator Laboratory (AREAL) is an electron accelerator project base... more Advanced Research Electron Accelerator Laboratory (AREAL) is an electron accelerator project based on photocathode RF gun. The first phase of the facility is a 5 MeV energy RF phototgun, which is currently under operation. The facility developments imply energy upgrade to 50 MeV with further delivery of the electron beam to the undulator sections for Free Electron Laser and coherent undulator radiation in MIR and THz frequency ranges, respectively. In this report the design study of AREAL 50 MeV facility main systems along with the beam dynamics and characteristics of expected radiation are presented.
Critical Reviews in Combinatorial Chemistry, 2006
MRS Proceedings, 2003
... Arik G. Alexanian, Hovsep N. Avetisyan1, Karapet E. Avjyan, Nikolay S. Aramyan, Garegin A. Al... more ... Arik G. Alexanian, Hovsep N. Avetisyan1, Karapet E. Avjyan, Nikolay S. Aramyan, Garegin A. Aleksanyan, Romen P. Grigoryan2, Ashot M. Khachatryan ... location of targets and substrates is chosen to achieve an overlap of fluxes of deposited materials on certain area of substrates ...
Applied Physics Letters, 2004
We experimentally demonstrate mid-infrared difference-frequency generation in suspended 181 nm th... more We experimentally demonstrate mid-infrared difference-frequency generation in suspended 181 nm thick GaAs waveguides. Generation of the idler at wavelengths between 2800 and 3150 nm is enabled by form-birefringent phase-matching in ultrahigh index-contrast waveguides. Nonlinear mixing has a measured efficiency of 0.4 W −1 in a 1.2 mm long waveguide using a CW signal tunable between 1490 and 1620 nm and a CW pump tunable between 1018 and 1032 nm at powers of a few mW.
International Journal of Infrared and Millimeter Waves, 2000
Two-photon and three-photon Raman scattering processes are considered. Analytical expressions are... more Two-photon and three-photon Raman scattering processes are considered. Analytical expressions are derived for the non-linear susceptibility, gain coefficient and generation threshold. It is shown that the resonant fluorescence accompanies the Raman scattering and the hot luminescence processes when the finite population of states is taken into account. Numerical evaluations show that the specification of the medium leads to low generation thresholds and high magnitudes of gain coefficients.
International Journal of Infrared and Millimeter Waves, 2000
The possibility of self-induced transparency is discussed in a semiconductor structure with 3D-qu... more The possibility of self-induced transparency is discussed in a semiconductor structure with 3D-quantized electron spectrum. A model structure is proposed, for which a significant decrease of pulse duration and an increase of power is obtained.
Measurement Science & Technology, 2005
... The thickness of deposited cadmium telluride films was in the range 0.11.2 µm and the surfac... more ... The thickness of deposited cadmium telluride films was in the range 0.11.2 µm and the surfacearea of obtained heterojunctions varied in ... Waves 14 2203 (b) Alexanian AG, Aramyan NS, Grigoryan RP, Khachatrian AM, Matevossian LA and Yeremyan AS 2002 On the optical ...
Measurement Science & Technology, 2005
Results of investigations of thin-film heterojunctions nInSb-nGaAs, pInSb-nCdTe, thin films PbTe,... more Results of investigations of thin-film heterojunctions nInSb-nGaAs, pInSb-nCdTe, thin films PbTe, Pb1-xSnxTe as well as periodic structures PbTe-Pba-PbTe produced by pulsed laser deposition (PLD) technique and possibilities of their application as IR photodetectors are discussed. PLD allows one to obtain abrupt interfaces of lattice-mismatched heterojunctions nInSb-nGaAs with large number of interface states. The sign reversal of photoresponse was observed in this structure in the wavelength range 3.5-6.5 µm. The wavelength at which the signal vanishes depends linearly on the applied bias voltage and shifts towards shorter wavelengths as the voltage increases. The device can operate as a sensitive null-signal detector and an infrared pyrometer. pInSb-nCdTe heterojunctions obtained by PLD in a regime of practically excluded interdiffusion of constituent materials reveal high sensitivity and fast operation (τ < 15 ns) in the spectral range 1.5-5.5 µm, which broadens with external voltage applied to the sample. This device can operate in photovoltaic, as well as in diode regimes. Optical memory effect was observed in heterojunction pInSb-nCdTe in the wavelength range 0.37-1.37 µm. PLD-produced PbTe, Pb1-xSnxTe films and periodic PbTe-Pba-PbTe structures with controllable parameters can be used as materials for detectors covering the wavelength range 1-10 µm.
In this work the PLD method was used for the growth of CdTe layers and layered [CdTe/Bi]m nanostr... more In this work the PLD method was used for the growth of CdTe layers and layered [CdTe/Bi]m nanostructures. Technological regimes were found for the growth of CdTe layers with the hexagonal wurtzite structure. The observed dependence of the structure of the layers (hexagonal or cubic) on the laser intensity is related to the energy state of the ablated material and its influence on the orientational properties of the substrate surface. It is shown that the temperature for the monocrystalline growth of this meta-stable phase can be decreased significantly (from 300°C to 170°C) by initial deposition of a seeding submonolayer of bismuth at moderate intensities of the evaporating laser. Such a decrease of the growth temperature allows the fabrication of multilayer [CdTe/Bi]m structures with abrupt interfaces.
Using the pulsed laser deposition (PLD) technique CdTe layers were obtained on various substrates... more Using the pulsed laser deposition (PLD) technique CdTe layers were obtained on various substrates from the target of compound material, as well as by sequential deposition from single sources of Cd and Te. Electron diffraction analyses have shown that layers deposited from single targets on InSb, KBr substrates crystallize in usual cubic zinc-blende structure of CdTe at the growth temperature of ~150 °C, i.e. significantly lower than in other traditional techniques - MBE, MOCVD, PVD. Layers deposited from CdTe compound target on mica substrates crystallize with hexagonal wurtzite structure; and the single-crystalline growth of layers is observed at 300 °C. It was established that significant decrease (down to 170 °C) in monocrystalline growth temperature for CdTe can be achieved in this case by deposition of initial submonolayer bismuth on mica substrate; the subsequent CdTe layer crystallizes in wurtzite structure with the plane lattice parameter close to that of the bismuth (4.546 Å). Lattice-matched multilayer structures CdTe-Bi-CdTe--- were fabricated based on this technique. The observed peculiarities of dependence of layer structure on the intensity of evaporating laser and substrate temperature is related to the energy state of laser-ablated material plasma and its influence on orienting properties of substrate surface.
Transverse emittance is one of the most important properties for high-brightness electron beams u... more Transverse emittance is one of the most important properties for high-brightness electron beams used for X-Ray free-electron lasers. The photo injector test facility at DESY in Zeuthen (PITZ) focuses on the development of high-brightness electron sources. The two main methods to measure the emittance are the quadrupole scan and the slit scan. Combining either of these methods with a transverse deflecting cavity allows the measurement of the slice emittance. At PITZ, space-charge effects at the low beam momentum of 24 MeV/c complicate in particular the quadrupole scan. This has to be considered in the emittance measurements. First slit-scan based slice emittance results will be shown next to studies on the beam transport for quadrupole scans.
In addition, the optical laboratories require a clean environment in order to avoid deposition of... more In addition, the optical laboratories require a clean environment in order to avoid deposition of dust on-and damage the optics. The laser laboratory is equipped with a conditioner with dust collecting filters. Nevertheless, the students are asked to wear the clean jacks and replacement shoes or polyethylene covers available at the entrance of the Laser room.
International Journal of Molecular Sciences, 2021
The development of new laser-driven electron linear accelerators, providing unique ultrashort pul... more The development of new laser-driven electron linear accelerators, providing unique ultrashort pulsed electron beams (UPEBs) with low repetition rates, opens new opportunities for radiotherapy and new fronts for radiobiological research in general. Considering the growing interest in the application of UPEBs in radiation biology and medicine, the aim of this study was to reveal the changes in immune system in response to low-energy laser-driven UPEB whole-body irradiation in rodents. Forty male albino Wistar rats were exposed to laser-driven UPEB irradiation, after which different immunological parameters were studied on the 1st, 3rd, 7th, 14th, and 28th day after irradiation. According to the results, this type of irradiation induces alterations in the rat immune system, particularly by increasing the production of pro- and anti-inflammatory cytokines and elevating the DNA damage rate. Moreover, such an immune response reaches its maximal levels on the third day after laser-driven U...
Journal of Electronic Materials, 2016
We present the results of a study on localized electronic centers formed in crystals by external ... more We present the results of a study on localized electronic centers formed in crystals by external influences (impurity introduction and irradiation). The main aim is to determine the nature of these centers in the forbidden gap of the energy states of the crystal lattice. For the case of semiconductors, silicon (Si) was applied as model material to determine the energy levels and concentration of radiation defects for application to both doped and other materials. This method relies on solving the appropriate equation describing the variation of the charge carrier concentration as a function of temperature n(T) for silicon crystals with two different energy levels and for a large set of N 1 , N 2 (concentrations of electronic centers at each level), and n values. A total of almost 500 such combinations were found. For silicon, energy level values of e 1 = 0.22 eV and e 2 = 0.34 eV were used for the forbidden gap (with corresponding slopes determined from experimental temperature-dependent Halleffect measurements) and compared with photoconductivity spectra. Additionally, it was shown that, for particular correlations among N 1 , N 2 , and n, curve slopes of e 1 /2 = 0.11 eV, e 2 /2 = 0.17 eV, and a = 1/2(e 1 + e 2) = 0.28 eV also apply. Comparison between experimental results for irradiation of silicon crystals by 3.5-MeV energy electrons and Co 60 c-quanta revealed that the n(T) curve slopes do not always coincide with the actual energy levels (electronic centers).
Frontiers in Optics 2016, 2016
We experimentally demonstrate solitonic self-spectral compression for noisy supercontinuum radiat... more We experimentally demonstrate solitonic self-spectral compression for noisy supercontinuum radiation in a single-mode fiber. The numerical modeling of the process shows the prospects of the noise nonlinear suppression for partially coherent pulses.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2016
The AREAL laser-driven RF gun provides 2-5 MeV energy ultrashort electron pulses for experimental... more The AREAL laser-driven RF gun provides 2-5 MeV energy ultrashort electron pulses for experimental study in life and materials sciences. We report the first experimental results of the AREAL beam application in the study of molecular-genetic effects, silicon-dielectric structures, ferroelectric nanofilms, and single crystals for scintillators.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2016
Advanced Research Electron Accelerator Laboratory (AREAL) is a 50 MeV electron linear accelerator... more Advanced Research Electron Accelerator Laboratory (AREAL) is a 50 MeV electron linear accelerator project with a laser driven RF gun being constructed at the CANDLE Synchrotron Research Institute. In addition to applications in life and materials sciences, the project aims as a test facility for advanced accelerator and radiation source concepts. In this paper, the AREAL RF photoinjector performance, the facility design considerations and its highlights in the fields of free electron laser, the study of new high frequency accelerating structures, the beam microbunching and wakefield acceleration concepts are presented.
Journal of Modern Physics, 2018
This paper reports results from an investigation of the interaction of displaced Si-self atoms (I... more This paper reports results from an investigation of the interaction of displaced Si-self atoms (I) and their vacancies (V), with impurities in crystalline silicon (Si), as induced by micro-second pulse duration irradiation with electrons at different energies: 3.5, 14, 25 and 50 MeV and pico-second pulse duration with energy 3.5 MeV. V-V, I-impurity atom and V-impurity atom interactions are analyzed both experimentally and as modeled using computer simulations. A process of divacancy (V 2) accumulation in the dose-dependent linear region is investigated. The effect of impurities on recombination of correlated divacancies, and I-atoms that had become displaced from regular lattice points is estimated by computer modeling of an appropriate diffusion-controlled process. It is concluded that the experimental results can be interpreted quantitatively in terms of a strongly anisotropic quasi-one-dimensional diffusion of displaced I-atoms. In addition, a significant difference is found between the effects of pico-second duration electron beam irradiation, which causes the formation of A-centre (V + Oxygen) clusters, while when the beam is applied on a micro-second timescale, divacancies are created instead, although the electrons have the same energy in both cases.
Advanced Research Electron Accelerator Laboratory (AREAL) is an electron accelerator project base... more Advanced Research Electron Accelerator Laboratory (AREAL) is an electron accelerator project based on photocathode RF gun. The first phase of the facility is a 5 MeV energy RF phototgun, which is currently under operation. The facility developments imply energy upgrade to 50 MeV with further delivery of the electron beam to the undulator sections for Free Electron Laser and coherent undulator radiation in MIR and THz frequency ranges, respectively. In this report the design study of AREAL 50 MeV facility main systems along with the beam dynamics and characteristics of expected radiation are presented.
Critical Reviews in Combinatorial Chemistry, 2006
MRS Proceedings, 2003
... Arik G. Alexanian, Hovsep N. Avetisyan1, Karapet E. Avjyan, Nikolay S. Aramyan, Garegin A. Al... more ... Arik G. Alexanian, Hovsep N. Avetisyan1, Karapet E. Avjyan, Nikolay S. Aramyan, Garegin A. Aleksanyan, Romen P. Grigoryan2, Ashot M. Khachatryan ... location of targets and substrates is chosen to achieve an overlap of fluxes of deposited materials on certain area of substrates ...
Applied Physics Letters, 2004
We experimentally demonstrate mid-infrared difference-frequency generation in suspended 181 nm th... more We experimentally demonstrate mid-infrared difference-frequency generation in suspended 181 nm thick GaAs waveguides. Generation of the idler at wavelengths between 2800 and 3150 nm is enabled by form-birefringent phase-matching in ultrahigh index-contrast waveguides. Nonlinear mixing has a measured efficiency of 0.4 W −1 in a 1.2 mm long waveguide using a CW signal tunable between 1490 and 1620 nm and a CW pump tunable between 1018 and 1032 nm at powers of a few mW.
International Journal of Infrared and Millimeter Waves, 2000
Two-photon and three-photon Raman scattering processes are considered. Analytical expressions are... more Two-photon and three-photon Raman scattering processes are considered. Analytical expressions are derived for the non-linear susceptibility, gain coefficient and generation threshold. It is shown that the resonant fluorescence accompanies the Raman scattering and the hot luminescence processes when the finite population of states is taken into account. Numerical evaluations show that the specification of the medium leads to low generation thresholds and high magnitudes of gain coefficients.
International Journal of Infrared and Millimeter Waves, 2000
The possibility of self-induced transparency is discussed in a semiconductor structure with 3D-qu... more The possibility of self-induced transparency is discussed in a semiconductor structure with 3D-quantized electron spectrum. A model structure is proposed, for which a significant decrease of pulse duration and an increase of power is obtained.
Measurement Science & Technology, 2005
... The thickness of deposited cadmium telluride films was in the range 0.11.2 µm and the surfac... more ... The thickness of deposited cadmium telluride films was in the range 0.11.2 µm and the surfacearea of obtained heterojunctions varied in ... Waves 14 2203 (b) Alexanian AG, Aramyan NS, Grigoryan RP, Khachatrian AM, Matevossian LA and Yeremyan AS 2002 On the optical ...
Measurement Science & Technology, 2005
Results of investigations of thin-film heterojunctions nInSb-nGaAs, pInSb-nCdTe, thin films PbTe,... more Results of investigations of thin-film heterojunctions nInSb-nGaAs, pInSb-nCdTe, thin films PbTe, Pb1-xSnxTe as well as periodic structures PbTe-Pba-PbTe produced by pulsed laser deposition (PLD) technique and possibilities of their application as IR photodetectors are discussed. PLD allows one to obtain abrupt interfaces of lattice-mismatched heterojunctions nInSb-nGaAs with large number of interface states. The sign reversal of photoresponse was observed in this structure in the wavelength range 3.5-6.5 µm. The wavelength at which the signal vanishes depends linearly on the applied bias voltage and shifts towards shorter wavelengths as the voltage increases. The device can operate as a sensitive null-signal detector and an infrared pyrometer. pInSb-nCdTe heterojunctions obtained by PLD in a regime of practically excluded interdiffusion of constituent materials reveal high sensitivity and fast operation (τ < 15 ns) in the spectral range 1.5-5.5 µm, which broadens with external voltage applied to the sample. This device can operate in photovoltaic, as well as in diode regimes. Optical memory effect was observed in heterojunction pInSb-nCdTe in the wavelength range 0.37-1.37 µm. PLD-produced PbTe, Pb1-xSnxTe films and periodic PbTe-Pba-PbTe structures with controllable parameters can be used as materials for detectors covering the wavelength range 1-10 µm.
In this work the PLD method was used for the growth of CdTe layers and layered [CdTe/Bi]m nanostr... more In this work the PLD method was used for the growth of CdTe layers and layered [CdTe/Bi]m nanostructures. Technological regimes were found for the growth of CdTe layers with the hexagonal wurtzite structure. The observed dependence of the structure of the layers (hexagonal or cubic) on the laser intensity is related to the energy state of the ablated material and its influence on the orientational properties of the substrate surface. It is shown that the temperature for the monocrystalline growth of this meta-stable phase can be decreased significantly (from 300°C to 170°C) by initial deposition of a seeding submonolayer of bismuth at moderate intensities of the evaporating laser. Such a decrease of the growth temperature allows the fabrication of multilayer [CdTe/Bi]m structures with abrupt interfaces.
Using the pulsed laser deposition (PLD) technique CdTe layers were obtained on various substrates... more Using the pulsed laser deposition (PLD) technique CdTe layers were obtained on various substrates from the target of compound material, as well as by sequential deposition from single sources of Cd and Te. Electron diffraction analyses have shown that layers deposited from single targets on InSb, KBr substrates crystallize in usual cubic zinc-blende structure of CdTe at the growth temperature of ~150 °C, i.e. significantly lower than in other traditional techniques - MBE, MOCVD, PVD. Layers deposited from CdTe compound target on mica substrates crystallize with hexagonal wurtzite structure; and the single-crystalline growth of layers is observed at 300 °C. It was established that significant decrease (down to 170 °C) in monocrystalline growth temperature for CdTe can be achieved in this case by deposition of initial submonolayer bismuth on mica substrate; the subsequent CdTe layer crystallizes in wurtzite structure with the plane lattice parameter close to that of the bismuth (4.546 Å). Lattice-matched multilayer structures CdTe-Bi-CdTe--- were fabricated based on this technique. The observed peculiarities of dependence of layer structure on the intensity of evaporating laser and substrate temperature is related to the energy state of laser-ablated material plasma and its influence on orienting properties of substrate surface.