Neutron monitors detect secondary particles produced by the collision of cosmic rays and atmospheric nuclei. The need exists for a mini-neutron monitor data acquisition system (MNM-DAS) to replace the existing recording system of the calibration neutron monitor developed in 2003 at the North-West University Centre for Space Research. The MNM-DAS must also replace the recording system of a standard NM64 neutron monitor. This research thus includes the development of the MNM-DAS using Design Science Research (DSR) in conjunction with Systems Engineering (SE) to streamline the design phase and maximize research output. A literature study is conducted, where an overview of the calibration monitor system is provided, together with the objectives for the development of the MNM system. An abstract system architecture was drawn up in the conceptual design phase of the project to provide a coherent description of all system functions. The system architecture was derived for the existing system, including additional functions of the required system, by performing a functional analysis. The architecture describes the function and fit of each functional unit and all interfaces that form an integrated system. From the conceptual design and system architecture, a preliminary synthesis was done. Following the preliminary synthesis, electronic circuitry was developed to capture the arrival time of pulses from the proportional neutron monitor counter tubes along with environmental variables, such as temperature, pressure, and location, which all influence the count rate. The MNM-DAS was successfully designed and developed by following this Systems-Engineering approach embedded into a Design Science Research framework. The MNM-DAS was constructed and tested, and is currently being used to provide neutron count data in real-world applications internationally. / MIng (Computer and Electronic Engineering), North-West University, Potchefstroom Campus, 2014

Neutron monitors detect secondary particles produced by the collision of cosmic rays and atmospheric nuclei. The need exists for a mini-neutron monitor data acquisition system (MNM-DAS) to replace the existing recording system of the calibration neutron monitor developed in 2003 at the North-West University Centre for Space Research. The MNM-DAS must also replace the recording system of a standard NM64 neutron monitor. This research thus includes the development of the MNM-DAS using Design Science Research (DSR) in conjunction with Systems Engineering (SE) to streamline the design phase and maximize research output. A literature study is conducted, where an overview of the calibration monitor system is provided, together with the objectives for the development of the MNM system. An abstract system architecture was drawn up in the conceptual design phase of the project to provide a coherent description of all system functions. The system architecture was derived for the existing system, including additional functions of the required system, by performing a functional analysis. The architecture describes the function and fit of each functional unit and all interfaces that form an integrated system. From the conceptual design and system architecture, a preliminary synthesis was done. Following the preliminary synthesis, electronic circuitry was developed to capture the arrival time of pulses from the proportional neutron monitor counter tubes along with environmental variables, such as temperature, pressure, and location, which all influence the count rate. The MNM-DAS was successfully designed and developed by following this Systems-Engineering approach embedded into a Design Science Research framework. The MNM-DAS was constructed and tested, and is currently being used to provide neutron count data in real-world applications internationally. / MIng (Computer and Electronic Engineering), North-West University, Potchefstroom Campus, 2014

Thesis (M.Sc. (Physics))--North-West University, Potchefstroom Campus, 2008.

The propagation of high-energy cosmic rays is influenced by the time-varying heliospheric magnetic field embedded in the solar wind, and by the geomagnetic field. To penetrate through this geomagnetic field, they must have a rigidity that exceeds the geomagnetic cutoff rigidity for a given position on the earth. In the atmosphere, the primary cosmic rays interact with atmospheric nuclei, to form a cascade of secondary particles. Neutron monitors record these secondary cosmic rays, mainly the neutrons, with energies about a decade higher than detected by most spacecraft. Since neutron monitors are integral detectors, each with its own detection efficiency, energy spectra cannot readily be derived from their observations. One way to circumvent this is by conducting latitudinal surveys with mobile neutron monitors. Another way is to use the worldwide stationary neutron monitor network, but then the counting rates of these monitors must be normalised sufficiently accurate against one another. For this reason two portable calibration neutron monitors were built at the Potchefstroom campus of the North-West University and completed in 2002. To achieve sufficient calibration accuracy, several properties of the calibrator are investigated in this work. Effects such as atmospheric pressure variations, diurnal variations, short-term scintillations, and multiplicity, contribute to the fluctuations of the counting rate of a neutron monitor. Due to these effects, the coefficient of variation of the calibrator is determined to be -40% larger than the Poisson deviation. The energy response of the calibrator over the cutoff rigidity interval from the poles to the equator is investigated, with the result that it is almost 4% larger than that of a standard 3NM64 neutron monitor. It is also determined that not only the calibrator, but also the stationary NM64 and IGY neutron monitors, have fairly large instrumental temperature sensitivity, which must be accounted for in calibration procedures. Furthermore, the calibrator has a large sensitivity to the type of surface beneath it, influencing its counting rate by as much as 5%. This investigation is incomplete and requires further experimentation before the calibration of the stationary neutron monitors can start. When calibrations of a significant number of the worldwide neutron monitors are done, their intensity spectra as derived from differential response functions, will provide experimental data for modulation studies at rigidities above 1 GV. / Thesis (Ph.D. (Physics))--North-West University, Potchefstroom Campus, 2006.

The propagation of high-energy cosmic rays is influenced by the time-varying heliospheric magnetic field embedded in the solar wind, and by the geomagnetic field. To penetrate through this geomagnetic field, they must have a rigidity that exceeds the geomagnetic cutoff rigidity for a given position on the earth. In the atmosphere, the primary cosmic rays interact with atmospheric nuclei, to form a cascade of secondary particles. Neutron monitors record these secondary cosmic rays, mainly the neutrons, with energies about a decade higher than detected by most spacecraft. Since neutron monitors are integral detectors, each with its own detection efficiency, energy spectra cannot readily be derived from their observations. One way to circumvent this is by conducting latitudinal surveys with mobile neutron monitors. Another way is to use the worldwide stationary neutron monitor network, but then the counting rates of these monitors must be normalised sufficiently accurate against one another. For this reason two portable calibration neutron monitors were built at the Potchefstroom campus of the North-West University and completed in 2002. To achieve sufficient calibration accuracy, several properties of the calibrator are investigated in this work. Effects such as atmospheric pressure variations, diurnal variations, short-term scintillations, and multiplicity, contribute to the fluctuations of the counting rate of a neutron monitor. Due to these effects, the coefficient of variation of the calibrator is determined to be -40% larger than the Poisson deviation. The energy response of the calibrator over the cutoff rigidity interval from the poles to the equator is investigated, with the result that it is almost 4% larger than that of a standard 3NM64 neutron monitor. It is also determined that not only the calibrator, but also the stationary NM64 and IGY neutron monitors, have fairly large instrumental temperature sensitivity, which must be accounted for in calibration procedures. Furthermore, the calibrator has a large sensitivity to the type of surface beneath it, influencing its counting rate by as much as 5%. This investigation is incomplete and requires further experimentation before the calibration of the stationary neutron monitors can start. When calibrations of a significant number of the worldwide neutron monitors are done, their intensity spectra as derived from differential response functions, will provide experimental data for modulation studies at rigidities above 1 GV. / Thesis (Ph.D. (Physics))--North-West University, Potchefstroom Campus, 2006.

Thesis (M.Sc. (Physics))--North-West University, Potchefstroom Campus, 2008.

Thesis (M.Sc. (Physics))--North-West University, Potchefstroom Campus, 2008.

Cosmic-ray fluctuations are monitored by neutron monitors using several different kinds of proportional counter tubes. An important component of these monitors is the electronic subsystem that registers and counts output pulses from these counter tubes. Part of the electronic subsystem is a specific preamplifier. The pulse-height distribution curve of the existing preamplifier used in the neutron monitor system at the Centre for Space Research at the North-West University was found to be incorrect, and therefore the pulse-height information cannot be used for further research on the counter tube characteristics. A correct pulse-height distribution implies that the envelope of the pulse, as generated by an amplifier, has a very specific shape as a result of the physics that governs the generation of pulses in the neutron counter tube. It was therefore proposed that a new charge-sensitive preamplifier be synthesized to provide an output that provides the correct pulse-height distribution graph for a neutron monitor system. The Centre for Space Research at the North-West University is in the process of designing and building a new mini neutron monitor system. The new charge-sensitive preamplifier will be implemented into this updated system. Ultimately, the electronic subsystem must be able to provide a pulse-height distribution graph at the push of a button, thus making the preamplifier a key component in the new design. In this dissertation the theory of charge-sensitive amplifiers is researched following a design science research methodology. The results showed that a charge-sensitive amplifier can be synthesized to address both the real-world requirements and the theoretical requirements of this research. / MIng (Electrical and Electronic Engineering), North-West University, Potchefstroom Campus, 2014

Cosmic-ray fluctuations are monitored by neutron monitors using several different kinds of proportional counter tubes. An important component of these monitors is the electronic subsystem that registers and counts output pulses from these counter tubes. Part of the electronic subsystem is a specific preamplifier. The pulse-height distribution curve of the existing preamplifier used in the neutron monitor system at the Centre for Space Research at the North-West University was found to be incorrect, and therefore the pulse-height information cannot be used for further research on the counter tube characteristics. A correct pulse-height distribution implies that the envelope of the pulse, as generated by an amplifier, has a very specific shape as a result of the physics that governs the generation of pulses in the neutron counter tube. It was therefore proposed that a new charge-sensitive preamplifier be synthesized to provide an output that provides the correct pulse-height distribution graph for a neutron monitor system. The Centre for Space Research at the North-West University is in the process of designing and building a new mini neutron monitor system. The new charge-sensitive preamplifier will be implemented into this updated system. Ultimately, the electronic subsystem must be able to provide a pulse-height distribution graph at the push of a button, thus making the preamplifier a key component in the new design. In this dissertation the theory of charge-sensitive amplifiers is researched following a design science research methodology. The results showed that a charge-sensitive amplifier can be synthesized to address both the real-world requirements and the theoretical requirements of this research. / MIng (Electrical and Electronic Engineering), North-West University, Potchefstroom Campus, 2014

<p>The development of a deuterium-deuterium/ tritium-deuterium (D-D/ D-T) pulsed neutron generator based on the principle of the Plasma Immersion Ion Implantation (PI3) technique is presented, in terms of investigating development of a compact system to generate an ultra short burst of mono-energetic neutrons (of order 1010 per second) during a short period of time (&lt / 20&mu / s) at repetition rates up to 1 kHz. The system will facilitate neutron detection techniques, such as neutron back-scattering, neutron radiography and time-of-flight activation analysis.</p> <p><br /> Aspects addressed in developing the system includes (a) characterizing the neutron spectra generated as a function of the target configuration/ design to ensure a sustained intense neutron flux for long periods of time, (b) the system was also characterised as a function of power supply operating conditions such as voltage, current, gas pressure and plasma density.</p>