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Neutron sources in science and industry
Andrýsek, Jan ; Zeman, Miroslav (referee) ; Král, Dušan (advisor)
This bachelor thesis is composed of literature review on the topic of neutron sources and experimental component discussing the reaction rate in an experimental model of a neutron source dependent on the isotope in used foil. The most used neutron sources in the world and in the Czech Republic are mentioned. The creation of neutrons in radionuclide sources in AmBe and PuBE, nuclear reactors, spallation sources and fusion neutron generators are described, together with their utilisation in research and industry. The practical part contains description of the design (\(\gamma \), n) of a neutron source in MCNP programme and its consecutive calculation using the Monte-Carlo method. The input for nuclear reaction are electrons accelerated onto energy of 70 MeV. These electrons strike the target, where the effect of braking radiation generates gamma rays. Radiation integrates with the nuclei of the convertor from beryllium oxide or lithium salt. The results analysed and discussed are used from experimental measurements in Yerevan for foils from isotopes 197-Au, 209-Bi and 59-Co. These foils were used in models with convertors from Beo and LiCl.
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Shielding and detection of neutrons
Černý, Tomáš ; Šťastný, Ondřej (referee) ; Katovský, Karel (advisor)
The master’s thesis provides an overview of available neutron sources in terms of neutron yields and energy spectrum of emitted neutrons. Reactions of neutrons with matter, especially neutron scattering and radiation capture, are described. The possibilities neutron neutron detection and spectrometry are also described. The following experiment deals with a design of suitable shielding materials and the analysis of the moderated energy spectrum of neutron flux. The properties of the neutron field were measured using detection by activation. Subsequently, a simulation of the problem was performer in the MCNP program. In the end, the achieved results are compared and evaluated.
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Study of reaction cross-sections important for advanced nuclear systems
Chudoba, Petr ; Wagner, Vladimír (advisor) ; Krása, Antonín (referee) ; Krtička, Milan (referee)
The doctoral thesis is focused on measurements of neutron cross-sections mainly cross-sections of (n,xn) threshold reactions. With the dawn of advanced nuclear systems such as fast reactors of GenIV, accelerator driven system or even fusion reactors, monitoring of fast neutron fields will gain on importance. The activation detectors are one of the viable options how to monitor these neutron fields and (n,xn) reactions would be one of the best options how to do such monitoring. There is one condition though. We need to have good cross- section data in high neutron energy region. Unfortunately, the current situation is rather bad. There is only a small amount of reliable data for neutron energies above 20 MeV and with increasing energy, the situation gets only worse. For this reason, we measure the cross-sections of (n,xn) reactions on perspective materials such as yttrium, gold and tantalum with neutron energies from 17.4 up to 94 MeV. In this thesis, the measurements together with motivation and methodology are described. Obtained results are in agreement with existing data. Severe discrepancies were observed between the predictions and experimental data for high order (n,xn) reactions. This problem is discussed and solved. The results in this region are in form of cross-section values and also...
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Neutron sources in science and industry
Andrýsek, Jan ; Zeman, Miroslav (referee) ; Král, Dušan (advisor)
This bachelor thesis is composed of literature review on the topic of neutron sources and experimental component discussing the reaction rate in an experimental model of a neutron source dependent on the isotope in used foil. The most used neutron sources in the world and in the Czech Republic are mentioned. The creation of neutrons in radionuclide sources in AmBe and PuBE, nuclear reactors, spallation sources and fusion neutron generators are described, together with their utilisation in research and industry. The practical part contains description of the design (\(\gamma \), n) of a neutron source in MCNP programme and its consecutive calculation using the Monte-Carlo method. The input for nuclear reaction are electrons accelerated onto energy of 70 MeV. These electrons strike the target, where the effect of braking radiation generates gamma rays. Radiation integrates with the nuclei of the convertor from beryllium oxide or lithium salt. The results analysed and discussed are used from experimental measurements in Yerevan for foils from isotopes 197-Au, 209-Bi and 59-Co. These foils were used in models with convertors from Beo and LiCl.
|
|
|
Shielding and detection of neutrons
Černý, Tomáš ; Šťastný, Ondřej (referee) ; Katovský, Karel (advisor)
The master’s thesis provides an overview of available neutron sources in terms of neutron yields and energy spectrum of emitted neutrons. Reactions of neutrons with matter, especially neutron scattering and radiation capture, are described. The possibilities neutron neutron detection and spectrometry are also described. The following experiment deals with a design of suitable shielding materials and the analysis of the moderated energy spectrum of neutron flux. The properties of the neutron field were measured using detection by activation. Subsequently, a simulation of the problem was performer in the MCNP program. In the end, the achieved results are compared and evaluated.
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Study of reaction cross-sections important for advanced nuclear systems
Chudoba, Petr ; Wagner, Vladimír (advisor) ; Krása, Antonín (referee) ; Krtička, Milan (referee)
The doctoral thesis is focused on measurements of neutron cross-sections mainly cross-sections of (n,xn) threshold reactions. With the dawn of advanced nuclear systems such as fast reactors of GenIV, accelerator driven system or even fusion reactors, monitoring of fast neutron fields will gain on importance. The activation detectors are one of the viable options how to monitor these neutron fields and (n,xn) reactions would be one of the best options how to do such monitoring. There is one condition though. We need to have good cross- section data in high neutron energy region. Unfortunately, the current situation is rather bad. There is only a small amount of reliable data for neutron energies above 20 MeV and with increasing energy, the situation gets only worse. For this reason, we measure the cross-sections of (n,xn) reactions on perspective materials such as yttrium, gold and tantalum with neutron energies from 17.4 up to 94 MeV. In this thesis, the measurements together with motivation and methodology are described. Obtained results are in agreement with existing data. Severe discrepancies were observed between the predictions and experimental data for high order (n,xn) reactions. This problem is discussed and solved. The results in this region are in form of cross-section values and also...
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