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Prototyp detektoru reaktorových antineutrin
Fajt, Lukáš ; Štekl, Ivan (advisor) ; Dragoun, Otokar (referee)
Title: Prototype of detector for detection of reactor's antineutrinos Author: Lukáš Fajt Department: Institute of Particle and Nuclear Physics Supervisor: Doc. Ing. Ivan Štekl, CSc., IEAP, CTU in Prague Abstract: This master thesis is related to the development of the complex detector of reac- tor's antineutrinos, so called S3 , which is based on the polystyrene scintillation detectors. The detector S3 (dimensions 40 x 40 x 40 cm3 ) will be located in the close vicinity of a nuclear reactor (5-12 m) and its purpose will be to measure reactor's power, isotopic composition of the nuclear fuel and moreover verification of the sterile neutrino hypothesis by detecting reactor's antineutrinos via the Inverse Beta Decay (IBD) interaction. Within the thesis, the first prototype of the antineutrino detector was constructed. It is composed of 18 scintillation plates (40 x 20 x 1 cm3 ) and corresponding electronics. With this prototype the first test with cosmic muons were performed. Within the thesis, the energy reso- lution of the scintillation plates was significantly improved by the optimization of their chemical composition and selection of the optimal refractive material. The proper energy resolution is very important for the detector functionality. In addition, a new methods for the production of coating layer...
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Monitoring of the energy scale in the KATRIN neutrino experiment
Slezák, Martin ; Vénos, Drahoslav (advisor) ; Štekl, Ivan (referee) ; Vorobel, Vít (referee)
The question of the absolute mass scale of neutrinos is of particular interest for particle physics, astrophysics, and cosmology. The KATRIN experiment (KArlsruhe TRItium Neutrino experiment) aims to address the effective electron antineutrino mass from the shape of the tritium β-spectrum with an unprecedented sensitivity of 0.2 eV/c2 . One of the major systematic effects concerns the experimental energy scale, which has to be stable at the level of only a few parts in a million. For its calibration and monitoring the monoener- getic electrons emitted in the internal conversion of γ-transition of the metastable isotope 83m Kr will be extensively applied. The aim of this thesis is to address the problem of KA- TRIN energy scale distortions and its monitoring in detail. The source of electrons based on 83m Kr embedded in a solid as well as the source based on gaseous 83m Kr are studied. Based on the experimental results an approach for the continuous stability monitoring is proposed. 1
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Electrical and optical properties of SiC single crystals
Brynza, Mykola ; Belas, Eduard (advisor) ; Štekl, Ivan (referee)
Silicon carbide is a semiconductor with a wide bandgap of up to 3.2 eV and is capable of operating in extreme conditions, high temperature and high energy modes. This work focuses on the investigation of electrical and optical properties of monocrystalline SiC by various methods including Raman spectroscopy, volt-ampere characteristics, L-TCT and spectroscopic techniques. The adhesion of contacts and the influence of different contact materials on the ability to detect ionizing radiation are also studied to optimize the technology of preparation of quality SiC-based radiation detectors.
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Electrical and optical properties of SiC single crystals
Brynza, Mykola ; Belas, Eduard (advisor) ; Štekl, Ivan (referee)
Silicon carbide is a semiconductor with a wide bandgap of up to 3.2 eV and is capable of operating in extreme conditions, high temperature and high energy modes. This work focuses on the investigation of electrical and optical properties of monocrystalline SiC by various methods including Raman spectroscopy, volt-ampere characteristics, L-TCT and spectroscopic techniques. The adhesion of contacts and the influence of different contact materials on the ability to detect ionizing radiation are also studied to optimize the technology of preparation of quality SiC-based radiation detectors.
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Room-temperature semiconducting detectors
Pekárek, Jakub ; Belas, Eduard (advisor) ; Oswald, Jiří (referee) ; Štekl, Ivan (referee)
Semiconducting material CdTe/CdZnTe has a huge application potential in spectroscopic room temperature radiation detection due to its properties. Such detectors can be used in medical applications, homeland security and for monitoring of nuclear facilities. However, the final device quality is influenced by many parameters. One crucial stage in detector fabrication is the proper surface treatment. The detailed study of surface treatments and their effect on final detector device is reported. Another crucial fact is the polarization of the detector caused by high radiation fluxes which negatively affects the use of such devices. The polarization occurs by capturing the photogenerated holes at the deep levels inside the semiconductor. The possible detector depolarization by infrared illumination during the detector operation has been experimentally verified and the obtained results are shown in this thesis. For optimal technology of preparation, it is also necessary to develop the fast characterization method for prepared detectors. The last aim of the thesis is to study the resulting quality of prepared planar and co-planar detectors by transient-current-technique (TCT). TCT is an electro-optical method allowing to determine variety of transport properties of radiation detectors, such as internal electric...
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Prototyp detektoru reaktorových antineutrin
Fajt, Lukáš ; Štekl, Ivan (advisor) ; Dragoun, Otokar (referee)
Title: Prototype of detector for detection of reactor's antineutrinos Author: Lukáš Fajt Department: Institute of Particle and Nuclear Physics Supervisor: Doc. Ing. Ivan Štekl, CSc., IEAP, CTU in Prague Abstract: This master thesis is related to the development of the complex detector of reac- tor's antineutrinos, so called S3 , which is based on the polystyrene scintillation detectors. The detector S3 (dimensions 40 x 40 x 40 cm3 ) will be located in the close vicinity of a nuclear reactor (5-12 m) and its purpose will be to measure reactor's power, isotopic composition of the nuclear fuel and moreover verification of the sterile neutrino hypothesis by detecting reactor's antineutrinos via the Inverse Beta Decay (IBD) interaction. Within the thesis, the first prototype of the antineutrino detector was constructed. It is composed of 18 scintillation plates (40 x 20 x 1 cm3 ) and corresponding electronics. With this prototype the first test with cosmic muons were performed. Within the thesis, the energy reso- lution of the scintillation plates was significantly improved by the optimization of their chemical composition and selection of the optimal refractive material. The proper energy resolution is very important for the detector functionality. In addition, a new methods for the production of coating layer...
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Monitoring of the energy scale in the KATRIN neutrino experiment
Slezák, Martin ; Vénos, Drahoslav (advisor) ; Štekl, Ivan (referee) ; Vorobel, Vít (referee)
The question of the absolute mass scale of neutrinos is of particular interest for particle physics, astrophysics, and cosmology. The KATRIN experiment (KArlsruhe TRItium Neutrino experiment) aims to address the effective electron antineutrino mass from the shape of the tritium β-spectrum with an unprecedented sensitivity of 0.2 eV/c2 . One of the major systematic effects concerns the experimental energy scale, which has to be stable at the level of only a few parts in a million. For its calibration and monitoring the monoener- getic electrons emitted in the internal conversion of γ-transition of the metastable isotope 83m Kr will be extensively applied. The aim of this thesis is to address the problem of KA- TRIN energy scale distortions and its monitoring in detail. The source of electrons based on 83m Kr embedded in a solid as well as the source based on gaseous 83m Kr are studied. Based on the experimental results an approach for the continuous stability monitoring is proposed. 1
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Influence of Deep Levels on Charge Transport in CdTe and CdZnTe
Dědič, Václav ; Franc, Jan (advisor) ; Oswald, Jiří (referee) ; Štekl, Ivan (referee)
CdTe and CdZnTe are promising materials for room temperature semiconductor X-ray and gamma ray detectors. The accumulation of a space charge at deep energy levels due to a band bending at contacts with Schottky barriers and due to trapped photogenerated charge may result in time dependent change of charge collection efficiency in CdTe and CdZnTe detectors known as polarization effect. This thesis is mainly focused on a study of electric field profiles in detectors under dark and high photon flux conditions simulating detector operation using crossed polarizers technique exploiting the electro-optic (Pockels) effect. It also deals with a study of deep levels responsible for the polarization and influence of contact metals on charge accumulation. Several experimental results are supported by theoretical simulations. The measurements were performed on three sets of samples equipped with different contact metals (Au, In) cut from three different n-type CdTe and CdZnTe materials. Energy levels were detected using methods based on the Pockels effect and discharge current measurements. Detailed study of internal electric field profiles has revealed a fundamental influence of near midgap energy levels related to crystal defects and contact metals on the polarization in semiconductor detectors under high radiation...
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