|
| |
|
|
The effect of the shape of the intake ports for pumping in a Scintillation detector.
Flídr, Karel ; Vyroubal, Petr (referee) ; Maxa, Jiří (advisor)
The thesis is concerned with the design of the shape of suction canals used for pumping in the scintillation detector. The goal is to perform analysis of the model of the detector according to the current conception and then perform an optimalisation of the suction canals as per demands to their function. In the beginning of the thesis the history of the microscope and electron microscopy is described. The next chapter is focused on a more detailed description of ESEM. The following charter is dedicated to describing the scintillation detector.The thesis recounts the kinds of liquid flow. In conclusion the programs SolidWorks and Ansys Fleunt are described. Next part of this thesis describes in detail parameters‘ settings of simulation calculation. Following chapter introduces designed changes of suction channels shape and its results are shown and described.
|
|
|
Influence of working conditions on the signal level detected by LVSTD detector
Tylich, Ondřej ; Zimáková, Jana (referee) ; Čudek, Pavel (advisor)
This bachelor project includes information about function of low vacuum scanning electron microscope and describes it’s parts. It explains the difference between low vacuum and high vacuum scannig electron microscope. Contains informations about creation and detection of secondary electrons using scintillation detectors. It describes the calculation of signal to noise ratio and the method for obtaining the values of signal. Project is focused to determine the value of signal with a change in working conditions obtained by using Low Vacuum Secondary Electron Detector TESCAN (LVSTD). The aim is to determine the stability of the effect of working conditions on LVSTD.
|
|
| |
|
|
Analysis of the gas flow when pumping vacuum for newly designed scintillation detector
Poruban, Milan ; Vaculík, Sebastian (referee) ; Maxa, Jiří (advisor)
The aim of this thesis is to study the issue of eniveromental scanning electron microscopy and pumping gas to create 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. 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 detector 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. At the end the simulation results of gas flow are compared for different variants of apertures and various pressures on the neck of a scintillation detector designed for optimum performance of the detector. The outcome of this thesis is model of newly designed scintillation detector with optimized shapes of apertures according to functional requirements.
|
|
|
Evaluation of gas flow in the scintillation detector at different profiles and sizes of holes in the screens that have shaped the network
Truhlář, Michal ; Špinka, Jiří (referee) ; Maxa, Jiří (advisor)
This work deals with the flow of gas in the scintillation detector. Thesis describes the function of an electron microscope, the composition, distribution and development of microscopes from the earliest to modern. The work also includes familiarization with SolidWorks 3D modeling in which is the electron microscope modeled and Cosmos FloWorks in which they are carried out simulations of gas flow. The paper is focused on the flow of gas in various shapes of the screen and various pressures in chamber of specimen. The results of the analysis of both apertures variants are compared with the request to minimize the pressures in the trajectory of the secondary electrons of well as in the chamber of specimen.
|
|
|
Using Computer Aided Engineering for analyse the detector
Novotný, Marek ; Špinka, Jiří (referee) ; Maxa, Jiří (advisor)
This diploma thesis deals with electron microscopy. Examined equipment is environmental scanning electron microscope (ESEM), namely scintillation a detector of the microscope. There is solved the influence of the profile of holes in diaphragms to the resulting pressure and gas flow on the path of secondary electrons at the detector. Introductory part of thesis informs about microscopy in general, with concentration on electron microscopy; especially on scanning microscope, because research is taken just on the environmental scanning electron microscope. Another part informs about both general principles of dynamics of gases and with finite volume method. Another part deals with concrete used software and with setting of individual parameters for calculation. At the beginning of calculation are used five basic profiles of holes in diaphragms for pressure 1000 Pa in the chamber of the sample. For modelling individual shapes is used 3D parametric modeller SolidWorks. Analysis of circulation of secondary electrons through detector is made by using Cosmos FloWorks module. The most suitable type of diaphragms is chosen from measured models. Another part of diploma thesis deals with measuring of chosen types of diaphragms for more pressures in the chamber of the sample; the pressure is 200, 400, 600, 800 and 1000 Pa. The outcomes of this research are both models of pressure and speed of circulation inside the detector and graphically processed values by using different diaphragms, respectively one type of a diaphragm in different pressures. Production drawings of each diaphragm, together with calculated models, are enclosed.
|
|
|
Construction scintillation detector with one aperture for environmental scanning electron microscope
Přichystal, Vít ; Vyroubal, Petr (referee) ; Maxa, Jiří (advisor)
The thesis is focused on the design of a scintillation detector with one screen for environmental scanning electron microscope. At the beginning of the work is an introduction to microscopy. Further work is focused on the description of ESEM microscope and a scintillation detector. The following chapter is devoted to the dynamics of flow. They list the types of flow and mathematical description of equations. The next chapter is about using the software and the way of solution of flow. In the following chapter describes a proposal of the diaphragm and extraction method of the detector area. They are described some of type aperture. The last chapter is the conclusion, where the work is summarized.
|
|
|
Scintillation SE Detector for Variable Pressure SEM
Tihlaříková, Eva ; Neděla, Vilém (referee) ; Jirák, Josef (advisor)
This project deals with the theme of environmental scanning electron microscopy (EREM). This method allows the examination of insulators and wet specimens without pretreatment and modification like drying and metallization. The principle of this method consists in using higher pressure in a specimen chamber. The pressure is within the range of 100 – 200 Pa. However, the pressure in the specimen chamber restricts the signal detection interference. The objective of the work is to explore the possibility of interference in secondary electron route detection by way of electrostatic field. The electrostatic field was realized with the system consisting of four electrodes located in front of the scintillation detector. It should have interfered the secondary electron´s trajectory to the detector chamber. The optimization of voltage on the electrodes was made by simulation program called SIMION. The simulation results were experimentally verified with laboratory EREM.
|
|
|
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.
|
guest ::
