Vidas Kalesinskas - Profile on Academia.edu (original) (raw)

Papers by Vidas Kalesinskas

Spectroscopy of defects in CdZnTe structures

Semiconductor Science and Technology

Dipole Field Representation in Discrete Basis

2006 International Conference on Microwaves, Radar & Wireless Communications, 2006

ABSTRACT The dipole electromagnetic field with any temporal and spatial dependence is represented... more ABSTRACT The dipole electromagnetic field with any temporal and spatial dependence is represented by a couple of two specific time and space-limited functions. The functions are expanded in terms of discrete basis of Hermite-Gaussian functions. The dipole electromagnetic field is calculated applying electric and magnetic Hertzian vectors which temporal dependencies are expressed in finite or infinite summation of Hermite-Gaussian functions. The calculation of radiated time and space-limited dipole fields produced by a given Hertzian vector expressed in terms of the couple introduced function are presented and their properties are discussed.

Evolution of the microwave-probed photoconductivity transients and of the proton induced luminesc... more Evolution of the microwave-probed photoconductivity transients and of the proton induced luminescence has simultaneously been examined in polycrystalline CdS layers evaporated in vacuum during exposure to a 1.6 MeV proton beam. The decrease of the intensity of luminescence peaked at 510 and 709 nm wavelengths and of values of the effective carrier lifetime has been correlated in dependence of proton irradiation fluence. The defect introduction rate has been evaluated by the comparative analysis of the laser and proton beam induced luminescence. The difference of a carrier pair generation mechanism inherent for light and for a proton beam has been revealed. V

Soft microwave mode in SbSI—type crystals

Http Dx Doi Org 10 1080 00150198408015327, Feb 8, 2011

Study of the electrical characteristics of CdZnTe Schottky diodes

Materials Science in Semiconductor Processing

Microwave resonant dielectric dispersion in SbS0.7Se0.3I crystals

Phase Transit, 1983

Microwave dielectric investigations of SbS0.7Se0.3 I crystals were carried out over the frequency... more Microwave dielectric investigations of SbS0.7Se0.3 I crystals were carried out over the frequency range 9 to 80 GHz. The main resonant dielectric dispersion caused by the soft mode occurs in the microwave range. On approaching the Curie point, the frequency of the microwave soft mode varies according to v2 r = A(T - T 0) with A = 1.1 ×

Analysis of electromagnetic waves scattering by dielectric and conducting cylinders in rectangular waveguide

12th International Conference on Microwaves and Radar. MIKON-98. Conference Proceedings (IEEE Cat. No.98EX195), 1998

ABSTRACT The paper presents a rigorous solution of the scattering problem by a circular dielectri... more ABSTRACT The paper presents a rigorous solution of the scattering problem by a circular dielectric and perfectly conducting cylinders of any radius and any height in the rectangular waveguide oriented perpendicularly to a wall. The method is based on the representation of fields in waveguide and dielectric medium by cylindrical eigenfunctions and application of boundary conditions on surfaces of the cylinder to evaluate the fields inside and outside the cylinder. The reflection and transmission coefficients are expressed through the fields. As an example the reflection and transmission coefficients versus frequency for various dielectric and metallic cylinders are computed. The comparison of numerical with experimental data is presented.

Determination of dielectric permittivity at microwaves using the eigenvalue problem

13th International Conference on Microwaves, Radar and Wireless Communications. MIKON - 2000. Conference Proceedings (IEEE Cat. No.00EX428), 2000

ABSTRACT A simple method for solving the inverse medium problem to determine the complex dielectr... more ABSTRACT A simple method for solving the inverse medium problem to determine the complex dielectric permittivity of a dielectric material at microwave frequencies is presented. The arbitrarily shaped dielectric sample is considered to be placed in a rectangular waveguide. The finite-difference technique and harmonic functions are applied to get a system of linear equations with measured reflection and/or transition coefficients added and solved through the eigenvalue problem. An algorithm to distinguish proper results from the system eigenvalues is defined by considering numerical solution properties. The system is tested using another method

A Numerical Investigation of Electromagnetic Scattering by Transversely Magnetized Ferrite Cylinder

Microwave Physics and Techniques, 1997

ABSTRACT The paper is devoted to the problem of scattering of plane electromagnetic wave by trans... more ABSTRACT The paper is devoted to the problem of scattering of plane electromagnetic wave by transversely magnetized ferrite cylinder. Exact analytical expressions for all partial cylindrical modes are obtained by solving Maxwell’s equations for transversely magnetized ferrite medium in cylindrical coordinate system. They are represented as the power series expansion and then are used to formulate and to solve the boundary problem. Numerical calculations of scattering patterns are also presented. Particular attention is paid to the possibility to control the scattering pattern by the external magnetic field.

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2007

CERN RD39 Collaboration is working on radiation hard cryogenic silicon detectors, for environment... more CERN RD39 Collaboration is working on radiation hard cryogenic silicon detectors, for environments such as at the Super-LHC. A promising technique for the operation of low temperature detectors and diodes is the current injection of pre-irradiated samples (CID). A new setup, based on the Cryogenic Transient Current Technique (C-TCT), has been built to characterize Si samples (CCE). In addition, we report here some preliminary measurements for the evaluation of laser and plasma-cut sensors developed for edgeless detectors, for which the sensitive area should extend to a few mm from the physical border.

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2009

Experimental results and simulations of Charge Collection Efficiency (CCE) of Current Injected De... more Experimental results and simulations of Charge Collection Efficiency (CCE) of Current Injected Detectors (CIDs) are focused. CID is a concept where the current is limited by the space charge. The injected carriers will be trapped by the deep levels. This induces a stable electric field through the entire bulk regardless of the irradiation fluence the detector has been exposed. Our results show that the CCE of CIDs is about two times higher than of regular detectors when irradiated up to 1 Â10 16 cm À2 . The higher CCE is achieved already at À50 1C temperatures.

A simple method of solving the inverse medium problem in order to determine the complex dielectri... more A simple method of solving the inverse medium problem in order to determine the complex dielectric constant of a lossy dielectric material at microwave frequencies is presented. The arbitrarily shaped dielectric sample placed in a rectangular waveguide is considered. Electromagnetic fields in the waveguide are expanded in series of harmonic functions. A set of linear equations is obtained using the finite-difference technique. An additional empirical condition, which is related to the measured reflection and/or transmission coefficients and results in an overdetermined system, is added and then the system is defined by the addition of a trivial extra parameter. The sample's dielectric properties are obtained by solving the resulting eigenvalue problem. An algorithm to extract proper results from the set of eigenvalues is defined by considering the properties of numerical solution. The system is tested by using an alternative method.

Microwave resonant dielectric dispersion in SbS 0.7 Se 0.3 I crystals

Phase Transitions, 1983

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2003

The recovery of the charge collection efficiency (CCE) at low temperatures, the so-called ''Lazar... more The recovery of the charge collection efficiency (CCE) at low temperatures, the so-called ''Lazarus effect'', was studied in Si detectors irradiated by fast reactor neutrons, by protons of medium and high energy, by pions and by gamma-rays. The experimental results show that the Lazarus effect is observed: (a) after all types of irradiation; (b) before and after space charge sign inversion; (c) only in detectors that are biased at voltages resulting in partial depletion at room temperature. The experimental temperature dependence of the CCE for proton-irradiated detectors shows non-monotonic behaviour with a maximum at a temperature defined as the CCE recovery temperature. The model of the effect for proton-irradiated detectors agrees well with that developed earlier for detectors irradiated by neutrons. The same midgap acceptor-type and donor-type levels are responsible for the Lazarus effect in detectors irradiated by neutrons and by protons. A new, abnormal ''zigzag''-shaped temperature dependence of the CCE was observed for detectors irradiated by all particles (neutrons, protons and pions) and by an ultra-high dose of g-rays, when operating at low bias voltages. This effect is explained in the framework of the double-peak electric field distribution model for heavily irradiated detectors. The redistribution of the space charge region depth between the depleted regions adjacent to p þ and n þ contacts is responsible for the ''zigzag''-shaped curves. It is shown that the CCE recovery temperature increases with reverse bias in all detectors, regardless of the type of radiation.

Recent results from the CERN RD39 Collaboration on super-radiation hard cryogenic silicon detectors for LHC and LHC upgrade

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2004

The CERN RD39 Collaboration is developing super-radiation hard cryogenic Si detectors for applica... more The CERN RD39 Collaboration is developing super-radiation hard cryogenic Si detectors for applications in experiments of the LHC and the future LHC Upgrade. Radiation hardness up to the fluence of 1016neq/cm2 is required in the future experiments. Significant improvement in the radiation hardness of silicon sensors has taken place during the past years. However, 1016neq/cm2 is well beyond the radiation

International Journal of Infrared and Millimeter Waves, 1997

The paper is devoted to the problem of scattering of plane electromagnetic wave by transversely m... more The paper is devoted to the problem of scattering of plane electromagnetic wave by transversely magnetized ferrite cylinder. Exact analytical expressions for all partial cylindrical modes are obtained by solving Maxwell's equations for transversely magnetized ferrite medium in cylindrical coordinate system. They are represented as the power series expansion and then are used to formulate and to solve the boundary problem. Numerical calculations of scattering patterns are also presented. Particular attention is paid to the possibility to control the scattering pattern by the external magnetic field.

$Research paper thumbnail of Wave diffraction by a finite set of azimuthally magnetized ferrite cylinders$

International Journal of Infrared and Millimeter Waves, 1996

The article is devoted to the problem of scattering of plane linear and circular electromagnetic ... more The article is devoted to the problem of scattering of plane linear and circular electromagnetic waves by a set of ferrite-coated cylinders. Particular attention is paid to the possibility of controlling the scattering pattern by the azimuthal magnetic field induced in the ferrite by the dc current in metal core of cylinders. It is shown that the best sensitivity can be obtained for the magnetic field, which provides the magnetic resonance inside ferrite layer. Relevant scattering patterns are also presented. Ferrites are frequently used in the development of control devices due to the fact that the magnetic constitutive characteristics of ferrites can be changed by the application of adc magnetic bias field. Earlier 1 we have considered the plane wave diffa'action by a finite set of longitudinally magnetized ferrite cylinders to show the principle possibility to control the scattered field. Actually the problem is equivalent to the diffraction by a set of dielectric cylinders ~ each having its own permittivity. One could get different shapes of scattering patterns due to the interference of the waves reradiated from each cylinder. The situation with azimuthally magnetized cylinder is quite different: the wave equations become the system of two coupled equations 3. So, quasi-Ez and quasi-Hz waves, whose fields inside ferrite cannot be expressed through cylindrical Bessel functions, exist. Consequently, the scattered field of the pure incident Ez or Hz polarized wave makes a combination of both Ez and Hz waves. In this paper we present the solutions of coupled wave equations for azimuthally magnetized ferrite medium in cylindrical coordinate system as the power series expansion. For the expansion coefficients we derive recurrent formulae that show that the first term can be chosen arbitrarily while all the others are being expressed through the first. Then applying boundary conditions for the fields we obtain an infinite set of linear equations that have to be solved numerically.

$Research paper thumbnail of Em wave diffraction by a finite set of magnetized ferrite cylinders$

International Journal of Infrared and Millimeter Waves, 1995

The paper presents a rigorous solution of the diffraction problem by a finite set of magnetized f... more The paper presents a rigorous solution of the diffraction problem by a finite set of magnetized ferrite cylinders. The main purpose of the research is to determine the steerability of scattering diagram of diffraction by several longitudinally magnetized ferrite cylinders. A plane wave scattering as well as main mode scattering by cylinders in the open end of rectangular waveguide are considered and numerical investigations are presented.

Study of The Soft Ferroelectric Modes by Microwave Dielectric Spectroscopy

Japanese Journal of Applied Physics, 1985