ALTO is a project, currently in the research and development phase, with the goal of constructing a Very High Energy (VHE) gamma-ray observatory in the southern hemisphere. It will detect the particle content reaching the ground from the interactions of either VHE gamma rays or cosmic rays in the atmosphere known as extensive air showers. In this thesis, we use an ALTO prototype built at Linneaus University to estimate the vertical muon intensity in Växjö. The atmospheric muons we detect at ground level come from hadronic showers caused by a cosmic ray entering the atmosphere. Such showers are considered background noise in the context of VHE gamma-ray astronomy, and the presence of muons is an important indicator of the nature of the shower, and thus of the primary particle. The measurement is done by isolating events that produce signals in two small scintillation detectors that are part of the ALTO prototype, and are placed almost directly above each other. This gives us a data set that we assume represents muons travelling along a narrow set of trajectories, and by measuring the rate of such events, we estimate the muon intensity. We estimate the corresponding momentum threshold using two different methods; Monte Carlo simulation and calculation of the mean energy loss. The vertical muon intensity found through this method is about 21% higher than commonly accepted values. We discuss some possible explanations for this discrepancy, and conclude that the most likely explanation is that the isolated data set contains a significant number of “false positives”, i.e., events that do not represent a single muon following the desired trajectory.

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.

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.

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.

The thesis deals with modifying and biulding of scintilation detector of secondary electrons for environmental scanning electron microscopy. It describes dilemma of environmental scanning electron microscopy, types of detectors and secondary electrons detection. The experimental part of this thesis focuses on the design and construction of new scintillation detector on the basis of simulations secondary electrons trajectories. Identifying the parameters, pressure dependencies and optimizations of electrode system of the detector realized.

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.

The observed imbalance of matter and anti-matter in the universe is one of physics' most fundamental unresolved questions. The leading theories to explain this imbalance require CP violation, and the neutron electric dipole moment (nEDM) is a sensitive parameter in its determination. Many new theories of physics beyond the standard model can be constrained or ruled-out by setting limits on the nEDM. Many next generation nEDM experiments require Ultra Cold Neutrons (UCN), produced in superfluid helium. One such experiment is cryoEDM. This thesis explores various types of UCN detection technologies applicable to cryoEDM or any high-density high-efficiency cryogenic nEDM experiment. Cryogenic Phonon Scintillation detectors (CPSD) are modified for this application by operating at 500 mK, and by using a titanium transition edge sensor for phonon signal readout. A CPSD is stabilised in the transition using a novel infra-red light feedback system which reduced the response time to O</m>(100 &mu;s). The detector is characterised and calibrated using an ²⁴¹Am &alpha; source. It was found to operate reliably at this elevated temperature and measure an alpha spectrum with 11% resolution at 5.5 MeV. Scintillators are identified as a promising technology for UCN detection at low temperature. Suitable materials that are bright with fast decay times and low &gamma; sensitivity are studied in the temperature range 300 - 6 K. Their light yield to alpha excitation, their decay time characteristics and spectroscopic properties under VUV excitation are investigated. This study includes the first comprehensive investigation of the luminescence properties of plastic scintillators and of ⁶LiF/ZnS(Ag) down to 6 K. It is found that there is no degradation of the luminescence or kinetic properties of these materials across the whole temperature range, revealing them as suitable cryogenic detector materials. Using a plastic scintillator, a prototype UCN detector for operation in liquid helium is designed, manufactured and tested. It is read out using WLS optical fibres to a room temperature photomultiplier. The detector is successfully tested with cold neutrons at the ISIS neutron science facility and found to effectively measure neutrons, with a signal that is clear from background. Recommendations are made for its integration into a cryogenic neutron EDM experiment. This low-cost detector offers a promising method for the passive detection of UCN in a challenging cryogenic environment, with minimal electric interference and low background sensitivity. This technology offers the potential for improved UCN detection efficiency and thus improved sensitivity of the measurement of the neutron EDM.

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.

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.

This thesis deals with scanning electron microscope working at higher pressure in the specimen chamber. The main goal was to study the voltage contrast on the PN junction of the transistor under suitable working conditions for using environmental scanning microscope. The observation of sample was enabled by a scintillation detector designed for observation of high pressure.