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Digital signal processing using field programmable gate arrays
Vykydal, Jan ; Kubíček, Michal (referee) ; Kolka, Zdeněk (advisor)
This thesis deals with the design, implementation and testing of an equipment that performs spectral analysis of a gamma radiation, based on the evaluation of pulses from a scintillation detector. The pulzes are pre-amplified and digitized, and their further processing takes place numerically in an FPGA, which allows a simple modification of the function of the developed device. After an introduction to the issue of gamma radiation spectroscopy with a focus on its detection, the thesis is devoted to the development of a multichannel analyzer hardware, whose individual parts are further described later. Next, the development of a digital signal processing system in the FPGA is described. Followed by an analysis of a microcontroller firmware, and a text protocol for the controlling of the device. Finally, the results of the work are discussed, with a focus on the test measurement of gamma radiation.
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Optimization of scintillation detector for detection of low energy signal electrons in electron microscopy
Tihlaříková, Eva ; Kadlec, Jaromír (referee) ; Uruba, Václav (referee) ; Neděla, Vilém (advisor)
The dissertation thesis deals with optimization of the scintillation detector for efficient detection of low energy signal electrons in a specimen chamber of a scanning electron microscope. The solution was based on the study of signal electron energy loss mechanisms during their interaction with a conductive layer and a scintillator that can be studied using simulations based on the stochastics Monte Carlo methods. Based on test simulations and their comparison with experimental data, the ideal Monte Carlo software was chosen and used for the study of signal electron energy losses during their transport through the conductive layer as well as following interaction with scintillator, in dependency on the signal electron energy. Simulation results allowed to define criteria for the optimization of the conductive layer. According to these parameters, the optimized layers were deposited on the surface of different scintillators and experimentally tested in the scintillation detector of the scanning electron microscope. Experimental measurements allowed to verify accomplished simulations and provide new information about impact of materials and thicknesses of conductive layers in combination with materials of scintillators and light guides. The increase of the detection efficiency of the scintillation detector equipped with optimised conductive layers and its capability to detect low energy signal electrons were experimentally proved.
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Scintillation SE detector for ESEM
Odehnal, Adam ; Špinka, Jiří (referee) ; Jirák, Josef (advisor)
Thesis deals with theoretical knowledge about scanning electron microscopy and environmental scanning electron microscopy. It describes principle of operation, signals generated by interaction between primary electron beam and specimen and means of detection of secondary electron signal in environmental conditions using scintillation detector. Furthermore, thesis focuses on optimization of detection od secondary electrons by adjusting electrode system of scintillation detector. Computer program Simion is used for modelling signal electron trajectories for proper adjustments. Simulation were starting-point for adjusting the design of the detector. Detection efficiency of adjusted detector was determined by evaluating signal magnitude from captured images, secondary electron detection capability from voltage contrast and quality of the captured images from signal/noise ratio.
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Contrast in image aquired by scintillation SE detector for VP SEM
Koudela, Oldřich ; Špinka, Jiří (referee) ; Jirák, Josef (advisor)
First part of this thesis is a theoretical essay which deals with the basics of scanning electron microscopy, with structure and function of a scanning electron microscope, its’ special case of an various pressure scanning electron microscope, electron interaction with surrounding environment and with a scintillation detector. The applied part of the thesis is focused on evaluation of material contrast on Cu-W specimen. Material contrast is evaluated for different pressures of water vapors in the microscope specimen chamber and for different detection conditions.
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Analysis of the dimensions of pumping channels in a new design of a scintillation detector
Kryll, Josef ; Bílek, Michal (referee) ; Maxa, Jiří (advisor)
The aim of this thesis is to study the issue of eniveromental scanning electron microscopy and pumping gas to create a vacuum in the newly designed scintillation detector. Further, creating a model of recently proposed scintillation detector and simulating and analyzing pumping gas in differentially pumped chamber of detector and the results compare with the previous model. The theoretical part deals with electron microscopy, electron sources, electron optics and secondary electrons detectors. It is also presented which signals are generated by the electron beam on the surface of a solid. Further fluid flow issues and equations describing the flow in the solved chamber are dismantled. Furthermore, the impact of gaseous environment on the trajectory of primary electrons, because there are collisions of primary beam with atoms and molecules of gas. The following section discusses creating, quality and importance of the network in mathematical modelling. A method of a final volume used to calculate the differential equations describing the flow of gas at the premises of the microscope is described . The practical part consists in creating a model of scintillation detector and analyzing the gas flow in drawing a vacuum in the newly designed scintillation detector. Furthermore, the simulation results are compared with the results of simulations on the older type of scintillation detector. The output of this thesis is model of recently proposed scintillation detector with visualized simulation results.
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Evaluation of Gas Flow at the Proposed Shapes of Scintillation Detector Aperture Sieves
Matloch, Roman ; Špinka, Jiří (referee) ; Maxa, Jiří (advisor)
This work describes briefly electron microscopy issue and physical model of fluid flow. Then the simplified three-dimensional model of scintillation detector will be created in SolidWorks system for 3D cubical models. The gas flow behind the screening in this 3D model will be analyzed and compared by method of finite cube method in SolidWorks Flow Simulation system. This screening will be analyzed in several variants: the screening with 0.6 mm opening and the screening with net-like openings. The results of analyses will be compared according to the requirements. The appropriate shapes from the analyzed parts will be practically measured.
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Digital signal processing using field programmable gate arrays
Vykydal, Jan ; Kubíček, Michal (referee) ; Kolka, Zdeněk (advisor)
This thesis deals with the design, implementation and testing of an equipment that performs spectral analysis of a gamma radiation, based on the evaluation of pulses from a scintillation detector. The pulzes are pre-amplified and digitized, and their further processing takes place numerically in an FPGA, which allows a simple modification of the function of the developed device. After an introduction to the issue of gamma radiation spectroscopy with a focus on its detection, the thesis is devoted to the development of a multichannel analyzer hardware, whose individual parts are further described later. Next, the development of a digital signal processing system in the FPGA is described. Followed by an analysis of a microcontroller firmware, and a text protocol for the controlling of the device. Finally, the results of the work are discussed, with a focus on the test measurement of gamma radiation.
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Estimation of the Point Radiation Source Activity Based on the Airborne Spectrometry
Jurečka, Tomáš ; Chromý, Adam (referee) ; Lázna, Tomáš (advisor)
The thesis deals with the localization of gamma-ray source and an estimation of its radiation activity with airborne spectrometry. In the theoretical parts are presented the types of ionizing radiation, the principles of measurement of gamma-ray by scintillation detectors and the explanation of airborne spectrometry. A revision of algorithms for data processing from aviation spectrometry was performed. In the practical part, the sensitivity of scintillation counter was determined depending on the height above the calibrated source. The mathematical methods for locating and estimating activity of the searched emitter were verified.
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Optimization of scintillation detector for detection of low energy signal electrons in electron microscopy
Tihlaříková, Eva ; Kadlec, Jaromír (referee) ; Uruba, Václav (referee) ; Neděla, Vilém (advisor)
The dissertation thesis deals with optimization of the scintillation detector for efficient detection of low energy signal electrons in a specimen chamber of a scanning electron microscope. The solution was based on the study of signal electron energy loss mechanisms during their interaction with a conductive layer and a scintillator that can be studied using simulations based on the stochastics Monte Carlo methods. Based on test simulations and their comparison with experimental data, the ideal Monte Carlo software was chosen and used for the study of signal electron energy losses during their transport through the conductive layer as well as following interaction with scintillator, in dependency on the signal electron energy. Simulation results allowed to define criteria for the optimization of the conductive layer. According to these parameters, the optimized layers were deposited on the surface of different scintillators and experimentally tested in the scintillation detector of the scanning electron microscope. Experimental measurements allowed to verify accomplished simulations and provide new information about impact of materials and thicknesses of conductive layers in combination with materials of scintillators and light guides. The increase of the detection efficiency of the scintillation detector equipped with optimised conductive layers and its capability to detect low energy signal electrons were experimentally proved.
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Analysis of the dimensions of pumping channels in a new design of a scintillation detector
Kryll, Josef ; Bílek, Michal (referee) ; Maxa, Jiří (advisor)
The aim of this thesis is to study the issue of eniveromental scanning electron microscopy and pumping gas to create a vacuum in the newly designed scintillation detector. Further, creating a model of recently proposed scintillation detector and simulating and analyzing pumping gas in differentially pumped chamber of detector and the results compare with the previous model. The theoretical part deals with electron microscopy, electron sources, electron optics and secondary electrons detectors. It is also presented which signals are generated by the electron beam on the surface of a solid. Further fluid flow issues and equations describing the flow in the solved chamber are dismantled. Furthermore, the impact of gaseous environment on the trajectory of primary electrons, because there are collisions of primary beam with atoms and molecules of gas. The following section discusses creating, quality and importance of the network in mathematical modelling. A method of a final volume used to calculate the differential equations describing the flow of gas at the premises of the microscope is described . The practical part consists in creating a model of scintillation detector and analyzing the gas flow in drawing a vacuum in the newly designed scintillation detector. Furthermore, the simulation results are compared with the results of simulations on the older type of scintillation detector. The output of this thesis is model of recently proposed scintillation detector with visualized simulation results.
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