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| 2. |
- Magnuson, Martin, 1965-
(författare)
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Process Control Methods for Operation of Superconducting Cavities at the LEP Accelerator at CERN
- 1992
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this work is to analyse the cryogenic process for cooling superconducting radio-frequency accelerator prototype cavities in the Large Electron-Positron collider (LEP) at CERN. A liquefaction cryoplant is analysed, including the production of liquid helium at 4.5 K, the systems for distribution and control of liquid helium, and the radio-frequency system used for accelerating particles. The cryogenic control problems of the cavities based on operation experiences of the prototype modules in 1991 and different solutions and modifications for the future cavity installations are presented in detail. In addition, different techniques for specifying the control programs for new cavities are evaluated. Various diagramming techniques, standards and methodologies, and ComputerAided Software Engineering (CASE) tools, are compared regarding their practical usefulness for the cryogenic process control.
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| 4. |
- Manzetti, Sergio, 1975-, et al.
(författare)
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Simulating galactical vorticity using a supersymmetric operator
- 2020
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Rapport (populärvet., debatt m.m.)abstract
- Simulations of galactic vorticity require the development of complex systems of equations to generate models that account for the gravity, mass, kinetic, and electromagnetic effects which govern cluster behaviour. In this study, a relationship is outlined through a series of steps, between the Einstein equations, the Ricci equations and the gravitational model of comoslogical bodies. This series of steps are then followed by the generation of a group of equations, including a supersymmetric equation which describes vorticity under the presence of an electromagnetic field for quantized systems. The relationship between the Einstein equations and the equation for quantum vorticity is ultimately the described and we outline the model of galactic vorticity through a nonlinear cluster model, which has direct similarities to the Kosterlitz-Thouless model for vorticity in quasi-ordered systems. The resulting supersymmetric model for describing galactic vorticity we here show suggests that galactic vorticity broke symmetry already at T=0, and by the effect of the galactic halo around the periphery, generates nonlinear vorticity through the shear property of the wavefunction. Most interestingly, this property of the wavefunction, which generates autonomous vorticity by the mere presence of a halo-boundary of the galactic cluster is independent of temperature. We describe by this that the nonlinear relationship between vortices in the cluster leads to a cumulative effect which generates an exchange interaction at the macroscopic level between clusters which is the source of irregular moment of inertia of galaxies, that has been attributed to dark matter. Our theory is thus that galactic rotations are both fueled by the mass of the galaxy by classical physics means as well as the nonlinear vortex interaction between clusters.
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| 5. |
- Ouahioune, Nedjma, 1999-
(författare)
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Project Material Physics - MOKE set-up to measure magnetic anisotropy
- 2020
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The Magneto-optical Kerr effect (MOKE) brings out the change in polarization of light reflected from a magnetic material. It is a powerful tool to study magnetic properties of materials among which the anisotropy. Various set-upsoperate in the material physics laboratory based on specific optical configurations. At room temperature, the RT-MOKE set-up uses reversing magnetic fields to measure the hysteresis loops of magnetic materials. Information about a number of important magnetic properties such as the magnetic anisotropy can be extracted from the hysteresis loops. The correlation between configuration of the set-up and reliable results is well established. Therefore, the aim of the project is to improve the system. More precisely, the project focuses on automating the manual adjustments precedinga measurement. The first step consists in learning how to operate the set-up. It is done by performing measurements on anisotropic magnetic samples. The second step is the automation of the analyser’s angle. As a requirement, time of the project is dedicated to learn Lab VIEW. Then, the automation of the analyser’s angle is executed. Finally, the last part is to automate the rotation of the sample as well as the positioning of both the detector and the analyser. The automation described bears the purpose to increase the accuracy especially by fixing reproducibility issues and ensure the settings are less time consuming. In this report, one can find the work carried out from January to May in order to develop the described automation, as part of a Bachelor’s project of 15 credits in material physics.
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| 6. |
- Buras, Bronislav, et al.
(författare)
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A high-pressure cell for neutron crystal spectrometry
- 1977
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Three fixed-scattering-angle methods for neutron scattering powder measurements using double- and triple-axis crystal spectrometers were tested: (1) the analyzer-scan method (AS), (2) the monochromator-scan method (MS), and (3) the monochromator-analyzer-scan method (MAS). A high-pressure cell, primarily for use in powder diffraction measurements, with scattering angles of 30o, 60o, 90o and 120o and a sample volume of about 0.8 cm3 was constructed and used in conjunction with the MS and MAS methods. At room temperature, this cell makes it possible to make measurements at pressures up to about 40 kbar and up to about 30 kbar at 300° C. The report includes a description of the diffraction methods and of the high-pressure cell. A few examples of experimental results are also given.
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| 7. |
- Ergül, Adem Björn, 1980-
(författare)
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Superconducting Nanowire Single-photon Detectors : WSi SNSPDs for Quantum Optics Applications
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In this study we have developed a new fabrication technique for Tungsten Silicide (WSi) Superconducting Nanowire Single-Photon Detectors (SNSPD). These detectors arespecifically designed to interact with the photons in the infra-red region of theelectro magnetic spectrum. Fabrication process is described in great detail with the intention of giving the readers a broad view about the facts or aspects of various situations they might face in the clean room processes. Ultimate goal for the project is to integrate these high temperature SNSPD detectors with the photonic circuits.
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| 8. |
- Forsemalm, Joakim, 1973, et al.
(författare)
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Station Community Transitions – A Matter of Push or Pull?
- 2013
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- A growing trend in Swedish physical planning and (sub)urban regeneration, as response to the need for more dense urban environments, is the increased focus on Station communities. These environments constitute a possibility for urban regions to grow in a sustainable fashion, at least discursively. In this context, the Gothenburg region - generally planned for car use but with high ambitions in terms of an objective to double the use of public transportation until 2025 – stand before interesting challenges and opportunities. Several major infrastructural projects focusing on commuter traffic are planned for take off within the next decade. These will affect not only the regional center in the shape of a train tunnel under great parts of Gothenburg, but also neighboring municipalities with train stations along the commuter routes into Gothenburg central station.From that background, in this report, three different municipalities, with stations located within a commuter distance of 20 minutes from that central station, are studied through the use of qualitative interviews and in some respect also document studies. Being informed by the same objective (i.e. the “doubling” of public transportation, a regional objective for all municipalities within the Gothenburg region), one could suspect that approaches on how to develop strategic places like communities around commuter train stations would have some resemblance. However, due to great variations in terms of push and pull factors, and not least differences when it comes to protagonists, urban identities and urban values expressed, what works in Mölnlycke in Härryda municipality doesn’t do so in Älvängen in Ale municipality, nor Floda, in Lerum municipality – and vice versa. This study shows that narration is just as important for the construction of station communities as are an advantageous geographical position along strategic train lines.The context of this report is Catch MR (Cooperative approaches to transport challenges in Metropolitan Regions), an Interreg IVC project that has run from 2010 throughout 2012. Catch MR has gathered twelve public partners in seven European regions - Berlin, Budapest, Oslo, Vienna, Rome, Gothenburg and Ljubljana around issues of life quality and competitiveness in urban regions. The study has been conducted as part of the research project Cities as value networks, which is a Mistra Urban Futures project. Mistra Urban Futures is a research and development center with its seat located in Gothenburg, Sweden.
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| 9. |
- George, Sebastian, 1990-
(författare)
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Energy and Angle Resolved Reflectivity of Plasmonic Nanostructures
- 2014
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- It has been apparent for some time that desirable plasmonic properties can be produced by combining certain component materials into a variety of nanometer-scale structures. A logical next step would be to develop the ability to actively tune the plasmonic properties of a particular nanostructured material. Exploration of such active tuning methods is at the forefront of plasmonics research. One such technique may be to make use of the magnetization within the material, controlled via external field, in order to alter the conditions necessary for plasmon excitation. Presented here are preliminary measurements of reflectivity for one such nanostructured material-a Co film patterned with a hexagonal lattice of holes. Such reflectivity measurements are useful in determining the optimal conditions for plasmon excitation in a sample, but are often limited to only a few wavelengths of incident light. Use of a white light source and spectrometer allows for resolution in both incidence angle and incident energy. Different polarizations of light as well as different incidence directions relative to the hole lattice are considered.
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| 10. |
- Magnuson, Martin, 1965-
(författare)
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An Electron Beam Heated Evaporation Source
- 1994
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- An electron beam evaporator has been assembled, tested and used for deposition of thin nickel films. Flux and deposition rates has been measured with an oscillating quartz crystal monitor (QCM), an ion sensor wire, and visible deposition on a mirror on front of the evaporator. A thin nickel rod of 2 mm diameter was found to improve the pressure in comparison to a 6-mm nickel rod. The flux was typically 3-4 Angstroms per minute during the test, but other flux rates can easily be achieved by changing the filament current and the acceleration voltage.
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