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The aim of this thesis is finding a geometric configuration that allows electron insertion into a Gabor plasma lens in order to increase the density of the confined electrons and provide ignition conditions at parameters where ignition is not possible. First, simulations using CST and bender were conducted to investigate several geometric configurations in terms of their performance of inserting electrons manually. One particular design has been chosen as a basis for an experiment. In order to prepare the experiment, further simulations using the code bender have been conducted to investigate the density distribution that is formed inside the Gabor lens when inserting electrons transversally in compliance with the chosen design. Additionally, bender was used to investigate the impact of the initial electron energy on the distribution inside the lens. Simulations with and without space charge effects have shown a significant impact of the space charge effects on the resulting density dstribution. Therefore, space charge effects have proven to be the major electron redistribution process. A given electron source was characterised in order to find the performance under the conditions inside a Gabor lens. In particular, a transversal magnetic field that will be present in the experiment has to be compensated by shielding the inner regions of the source by a μ-metal layer. Using a μ-metal shield, transversal magnetic fields are sufficiently tolerable to perform measurements in a Gabor lens. Additionally, operating close to 100 eV electron energy yields a maximum in the emitted current. Adding a Wehnelt cylinder to the electron source furthermore improves the extracted current to roughly 1 mA. A test stand consisting of a newly designed anode for the Gabor lens, as well as a terminal for the electron source, was constructed. The electron source was thoroughly characterised in the environment of the Gabor lens and the ignition properties of the new system were evaluated. In further experiments, electron beam assisted ignition by increasing the residual gas pressure was observed and the impact of the position of the electron source on the ignition properties was investigated. In addition, ignition of a sub-critical state, that is a state consisting of potential, magnetic field and pressure that did not yet perform ignition by itself, was performed by increasing the extracted current from the electron source. Finally, the electron source was used to influence a pre-ignited plasma. The density was measured, which was increased by the use of the electron source in most cases. This project is part of the EDEN collaboration (Electron DENsity boosting) of the NNP Group at IAP Frankfurt with INFN institutes in Bologna and Catania.
Electron identification with a likelihood method and measurements of di-electrons for the CBM-TRD
(2017)
In this work a likelihood method has been implemented and investigated as particle identification algorithm for the CBM-TRD.
The creation of the probability distributions for the likelihood method via V0-topologies seems to be feasible and the purity of the obtained samples is sufficient for the usage in the likelihood method.
The comparison between the ANN and the likelihood method shows no differences in the identification performance. The pion suppression factor reaches the same values for the same electron identification efficiencies and the yields of the resulting di-lepton signals are comparable. The signal-to-background ratios for both methods have the same values and show a value of about 10−2 in the invariant mass range of minv = 1.5 - 2.5 GeV/c2, which is expected to be sufficient to provide access to the thermal in-medium and QGP radiation.
The investigation of a detector system without a TRD shows no pion suppression for a momentum above p = 6 GeV/c. Therefore, the background contributions increase drastically and the signal-to-background ratio decreases at all invariant masses, but especially in the invariant mass range of minv = 1.5 - 2.5 GeV/c2.
The background contributions in the invariant mass range of minv = 1.5 - 2.5 GeV/c 2 are also influenced by the selected electron identification efficiency of the TRD, which significantly shifts the fraction of the eπ contributions relative to the total number of pairs.
Virtual machines are for the most part not used inside of high-energy physics (HEP) environments. Even though they provide a high degree of isolation, the performance overhead they introduce is too great for them to be used. With the rising number of container technologies and their increasing separation capabilities, HEP-environments are evaluating if they could utilize the technology. The container images are small and self-contained which allows them to be easily distributed throughout the global environment. They also offer a near native performance while at the same time aproviding an often acceptable level of isolation. Only the needed services and libraries are packed into an image and executed directly by the host kernel. This work compared the performance impact of the three container technologies Docker, rkt and Singularity. The host kernel was additionally hardened with grsecurity and PaX to strengthen its security and make an exploitation from inside a container harder. The execution time of a physics simulation was used as a benchmark. The results show that the different container technologies have a different impact on the performance. The performance loss on a stock kernel is small; in some cases they were even faster than no container. Docker showed overall the best performance on a stock kernel. The difference on a hardened kernel was bigger than on a stock kernel, but in favor of the container technologies. rkt showed performed in almost all cases better than all the others.
Cleaning an ion beam from unwanted fractions is crucial for intense ion beams. This thesis will explore separation methods using a collimation channel, electric and magnetic dipoles and a velocity selector for low intensity beams on an experimental basis. In addition, statistical data of degassing events during the commissioning of a pentode extraction system for beam energies from 20 - 120keV will be presented.
Anisotropic collective flow of protons resulting from non-central heavy ion collisions is a unique hadronic observable providing information about the early stage of the nuclear collision. The analysis of collective flow in the energy regime between 1-2 AGeV enables the study of the phase diagram of hadronic matter at a high baryochemical potential µb, as well as the analysis of the equation of state at densities up to the threefold of the ground state density ρ0.
The algorithms of the standard event plane method and the scalar product method are used to analyse directed and elliptic flow of protons in a centrality range of 0-40 % most central events.
Prior to the analysis of experimental data, the respective influence of the reconstruction procedure on the algorithms is examined using Monte Carlo simulations based on the Ultra relativistic Quantum Molecular Dynamics (UrQMD) model.
Subsequently, experimental data measured in April 2012 with the High Acceptance DiElectron Spectrometer (HADES) is analysed using both methods. About 7.3 · 109 Au+Au events at a kinetic beam energy of 1.23 AGeV, equivalent to a centre of mass energy of √sNN = 2.42 GeV were recorded. A multi-differential analysis is feasible as the HADES detector provides a good transverse momentum and rapidity coverage.
Both algorithms result in identical values for directed and elliptic flow across all centrality classes within the observable phase space of protons. The calculated integrated value of v2 at mid rapidity is in good agreement with world data.
In thesis I investigate the possibility that at the smallest length scale (Planck scale) the very notion of "dimension" needs to be revisited. Due to "quantum effects" spacetime might become very turbulent at these scales and properties like those of "fractals" emerge, including a "scale dependent dimension". It seems that this "spontaneous dimensional reduction" and the appearance of a minimal physical length are very general effects that most approaches to quantum gravity share. Main emphasis is given to the"spectral dimension" and its calculation for strings and p-branes.
Der digitale Wandel wirkt sich auf das alltägliche Leben in der modernen Lebenswelt im 21. Jahrhundert aus. Ob im Berufs- oder Privatleben, digitale Medien sind nicht mehr aus dem alltäglichen Leben wegzudenken und sie erleichtern das Leben maßgeblich.
E-Learning wird insbesondere in der Erwachsenenbildung benutzt und diese Branche "boomt". Umstritten ist dennoch, ob digitale Medien und E-Learning in Schulen eingesetzt werden sollten und ob ein Lernen und Lehren mit neuen Medien sinnvoll ist. Derzeitig ist keine bundesweite einheitliche Lehrerausbildung bezüglich des Umgangs mit digitalen Medien im Kontext Lehren und Lernen und den damit verbundenen Herausforderungen vorhanden.
Es stellt sich die Frage, wie neue Medien im Unterricht verwendet werden und welche Aspekte beim Lehren zu beachten sind.
Der digitale Wandel wirkt sich auf das alltägliche Leben in der modernen Lebenswelt im 21. Jahrhundert aus. Ob im Berufs- oder Privatleben, digitale Medien sind nicht mehr aus dem alltäglichen Leben wegzudenken und sie erleichtern das Leben maßgeblich.
E-Learning wird insbesondere in der Erwachsenenbildung benutzt und diese Branche "boomt". Umstritten ist dennoch, ob digitale Medien und E-Learning in Schulen eingesetzt werden sollten und ob ein Lernen und Lehren mit neuen Medien sinnvoll ist. Derzeitig ist keine bundesweite einheitliche Lehrerausbildung bezüglich des Umgangs mit digitalen Medien im Kontext Lehren und Lernen und den damit verbundenen Herausforderungen vorhanden.
Es stellt sich die Frage, wie neue Medien im Unterricht verwendet werden und welche Aspekte beim Lehren zu beachten sind.
Die Arbeit widmet sich der bisher wenig beachteten Demokratietheorie des neoliberalen Ökonomen und Sozialphilosophen Friedrich Hayeks. In seiner Ablehnung des Prinzips der Volkssouveränität scheint es Hayek nicht in erster Linie um die Kritik des demokratischen Elements zu gehen, sondern vielmehr um die moderne Idee staatlicher Souveränität schlechthin. Es ist folglich die Idee der Rechtssouveränität, so die grundlegende These, auf der Hayek seine doppelte Kritik von Naturrecht und Rechtspositivismus gründet. Entprechend ist der Staat in der von Hayek gezeichneten Utopie nicht länger Souverän, Ausdruck, Grund oder Herrscher (in) der Gesellschaft, sondern bloßes Mittel, um die "spontanen Ordnungen" der Gesellschaft (und der Märkte) zu schützen, ohne durch Gesetzgebung planen, gestalten oder intervenieren zu wollen. Allein solches, an den "Nomos" gebundenes, staatliches Handeln könne (und muss!) der "Meinung" der Menschen entsprechen. Die Klärung dieses sehr speziellen und auf David Hume zurückgehenden Verständnisses von "Meinung" erlaubt schließlich, das Denken Hayeks nicht nur hinsichtlich seines Souveränitätsbegriffs, sondern auch hinsichtlich seines Demokratiebegriffs vom Denken Carl Schmitts abzugrenzen. Entgegen dem prägenden Diskurs nach Cristi und Scheuerman, der die Kritik der hayekschen Theorie über die Problematisierung ihres schmittschen Gehalt unternimmt, soll die Arbeit den Blick dafür schärfen, dass der in Hayeks Theorie angelegte Autoritarismus auf eigenen philosophischen Füßen steht und sich nicht erschöpfend aus einem bewusst oder unbewusst übernommenen schmittschen Erbe erklären lässt.