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  • 1.
    Adler, Severino
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Hubbard to Falicov-Kimball-a DMFT[DMRG] study2017Student paper other, 10 credits / 15 HE creditsStudent thesis
  • 2.
    Ahlholm, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Physics Didactics.
    Fysikattityder hos gymnasieelever?: Trender bland intresse för fysik och fysikattityder bland svenska gymnasieelever2013Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Empirical research has shown that there are clear links between the interests, attitudes, and studentsuccess. The aim of the survey, which is the foundation of this report, was to measure how theinterest in physics and attitudes towards physics and physics education differs between the differentyears in upper secondary school. Maryland Physics Expectations (MPEX) Survey has been used tomeasure the attitudes. The questionnaire was answered by 605 respondents from technology andnatural science program from two upper secondary schools in central Sweden. Interest in physics islow on the investigated schools and it tends to become lower through the ages. Overall, there aremore unfavorable responses of the different attitude dimensions in third grade than in first grade. Concept is the dimension that has the most unfavorable response in both the second and third grade.In order to increase the conceptual understanding of upper secondary school students, shouldconceptual understanding be offered a greater part of the teaching. Examining conceptualunderstanding in homework assignments and tests are also preferable.

  • 3.
    Ahlvind, Julia
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    The Almighty Quasar — Destroyer of Worlds2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In the study of habitability of terrestrial exoplanets, both life-supporting conditions and the prevalence of transient life-threatening events need to be considered. One type of hazardous effect that has so far not received much attention is the thermal effect of a nearby active galactic nucleus (AGN), or in this particular case, the class of the AGN known as a quasar. In this work we investigate the thermal effect from a quasar by calculating the number of habitable terrestrial planets (HTP) in an elliptical or bulge-dominated galaxy, that goes extinct when exposed to the quasar radiation in a limited wavelength range. This is done by approximations and modelling along with pre-existing formulas and data from earlier publications. As a result, the influence by a quasar during the time span of quasar activity will have a less significant impact on the habitability in solar-type stellar systems than expected. Assuming tQSO = 108 yrs of quasar activity, results in the number of affected HTP, ≈ 1 × 105, 9 × 105 and 4 × 108 for isotropic spherical radiation and ≈ 1 × 106, 8 × 106 and 3 × 109 for a double-conical radiation. In terms of stellar mass fraction, ≈ 1.3%, 1.0%, 0.4% for isotropic radiation and ≈ 12.8%, 9.5%, 3.8% for conical, is affected. The results of this work are hoped to provide a rough estimation of the thermal impacts of a quasar on the habitability as well as to point out the most important parameters when considering this model.

  • 4.
    Aimard, Axelle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Crack speed in wood fibers composites and PLA2017Student paper other, 10 credits / 15 HE creditsStudent thesis
  • 5.
    Aksér, Marielle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Physics Didactics.
    Laborera i fysik, en självklarhet, men när?2014Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The theoretical background in this essay made clear that the students’ knowledge about physics improve, and they express a more positive attitude towards physics as a subject, when they have access to a more laboratory-based learning style. The aim of this study is to research how the placement of the lab relative to the lecture affects the students’ experiences and level of knowledge. The study involved students in year eight and was carried out during four weeks. A total of four lectures were held in addition to a total of eight labs devided on four lab-lessons. The students were divided into two different groups, one where the students were given lectures before they preformed the labs and one where the students had the labs prior to the corresponding lectures. Tests were given at the beginning and end of the study to evaluate any difference in knowledge and in addition to this the students answered surveys regarding their attitudes and experiences. The data belonging to each group was then compared. The result showed that the two groups improved their knowledge by nearly the same amount and any differences found regarding qualitative or quantitative knowledge between the two groups was minor. The one difference that could be found dealt with the students’ attitudes towards their education. The students in the group that had their lab-lesson before the corresponding lecture perceived the lecture as easier to understand than the other group. The perceived difficulty of the labs could not be connected to whether the students had the lab or the lecture first.

  • 6.
    Al Moulla, Khaled
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Turbulence at MHD and sub-ion scales in the magnetosheath of Saturn: a comparative study between quasi-perpendicular and quasi-parallel bow shocks using in-situ Cassini data2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The purpose of this project is to investigate the spectral properties of turbulence in the magnetosheath of Saturn, using in-situ magnetic field measurements from the Cassini spacecraft. According to models of incompressible, turbulent fluids, the energy spectrum in the inertial range scales as the frequency to the power of -5/3, which has been observed in the near-Earth Solar wind but not in the Terrestrial magnetosheath unless close to the magnetopause. 120 time intervals for when Cassini is inside the magnetosheath are identified — 40 in each category of behind quasi-perpendicular bow shocks, behind quasi-parallel bow shocks, and inside the middle of the magnetosheath. The power spectral density is thereafter calculated for each interval, with logarithmic regressions performed at the MHD and sub-ion scales separated by the ion gyrofrequency. The results seem to indicate similar behaviour as in the magnetosheath of Earth, without significant difference between quasi-perpendicular and quasi-parallel cases except somewhat steeper exponents at the MHD scale for the former. These observations confirm the role of the bow shock in destroying the fully developed turbulence of the Solar wind, thus explaining the absence of the inertial range.

  • 7.
    Albrecht, Felix
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Numerical modeling and simulation of the deformation of wood under an applied indentation load2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 8.
    Albrecht, Felix
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Numerical modeling and simulation of the deformation of wood under an applied indentation load2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 9.
    Ali, Babar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, High Energy Physics.
    Study of the performance of the Level-1 track trigger in the H→ττ→ee channel in ATLAS at high luminosity LHC2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 10.
    Alinder, Simon
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Effect of the convective electric field on the ion number density around a low activity comet2017Student paper other, 5 credits / 7,5 HE creditsStudent thesis
    Abstract [en]

    Vigren et al. (2015) presents an integral expression to calculate the ion number density around a low activity comet immersed in the solar wind's convective electric field. A certain parameter of the integral takes values of either 1 or 0 depending on whether a corresponding ion trajectory is feasible or not. The criteria used in the paper has been found not to be strict enough, yielding overestimated ion number densities in the cometary wake. The present project finds two new options for the criteria, one analytical and one numerical. The new numerical condition is tested in the same computations done in the original paper and compares the results of the old and new criteria. The new conditionis found to correct the previous error.

  • 11.
    Alinder, Simon
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Electron cooling in a cometary coma2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The ESA Rosetta spacecraft investigated comet 67P/Churyumov-Gerasimenko duringtwo years from August 2014 to the end of September 2016. The dual Langmuir probewas used to measure plasma parameters including the thermal energy of theelectrons. The observed thermal energy (or temperature) of the electrons was ratherhigh, in the range 5-10 eV almost throughout the mission. However, near perihelionthe Langmuir probe measurements indicated the prevalence of two electronpopulations with distinct temperatures, one hot (5-10 eV) and one cold (less than 1eV). It has been hypothesized that the electrons of the colder population wereformed relatively close to the nucleus and that they subsequently cooled by inelasticcollisions with the neutral gas. In this project work we develop a model for studyingelectron cooling in a cometary coma. The model takes into account collisions withwater molecules as well as the influence of a radial ambipolar electric field.

  • 12.
    Alinder, Simon
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Space Situational Awareness with the Swedish Allsky Meteor Network2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis investigates the use of the Swedish Allsky Meteor Network (SAMN) for observing, identifying, and determining the orbits of satellites. The overall goal of this project is to determine the feasibility of using such a network for Space Situational Awareness (SSA) purposes, which requires identification and monitoring of objects in orbit. This thesis is a collaboration with the Swedish Defense Research Agency (FOI) to support their efforts in SSA.

    Within the frame of this project, the author developed software that can take data of observations of an object collected from the all-sky cameras of SAMN and do an Initial Orbit Determination (IOD) of the object. An algorithm that improves the results of the IOD was developed and integrated into the software. The software can also identify the object if it is in a database that the program has access to or, if it could not be identified, make an approximate prediction of when and where the object will be visible again the next time it flies over. A program that analyses the stability of the results of the IOD was also developed. This measures the spread in results of the IOD when a small amount of artificial noise is added to one or more of the observed coordinates in the sky. It was found that using multiple cameras at different locations greatly improves the stability of the solutions.

    Gauss' method was used for doing the IODs. The advantages and disadvantages of using this method are discussed, and ultimately other methods, such as the Gooding method or Double R iteration, are recommended for future works. This is mostly because Gauss' method has a singularity when all three lines of sight from observer to object lie in the same plane, which makes the results unreliable.

    The software was tested on a number of observations, both synthetic and real, and the results were compared against known data from public databases. It was found that these techniques can, with some changes, be used for doing IOD and satellite identification, but that doing very accurate position determination required for full orbit determination is not feasible.

  • 13.
    Alonso i Fernández, Jaume
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Equivariant Cohomology and Localisation2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Equivariant localisation is based on exploiting certain symmetries of some systems, generally represented by a non-free action of a Lie group on a manifold, to reduce the dimensionality of integral calculations that commonly appear in theoretical physics. In this work we present Cartan's model of equivariant cohomology in different scenarios, such as differential manifolds, symplectic manifolds or vector bundles and we reproduce the main corresponding localisation results.

  • 14.
    Alves Vaccari, Paulo Roberto
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Near infrared and visible optical properties in electrochromic crystalline tungsten oxide thin films on ITO2010Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this project I have studied the optical properties of electrochromic crystalline tungsten oxide, WO3. The practical application could be for a window for desalination of sea water which requires a high absorption coefficient A(λ) for near infrared radiation (NIR), while at the same time a high transmittance T(λ) in the visible spectral range.

     

    An electrochromic (EC) material is a material that changes its optical properties when inserting or extracting ions by applying a voltage. The WO3 was prepared on a glass substrate coated by a transparent electrical conductor. The conductor used is tin doped indium oxide. In2O3:Sn, indium-tin-oxide (ITO). The preparation of the thin films has been carried out using DC magnetron reactive sputtering. The structure of unheated tungsten oxide is amorphous and once heated it is crystalline. Li+ ions were inserted into the tungsten oxide material with electrochemical methods to create the coloring effect. The optical properties were recorded in the 330 < λ < 2500 nm wavelength range by use of a Perkin-Elmer Lambda 9 spectrophotometer.

     

    The highest reflectance R(λ), approximately 50% in NIR and absorption coefficient

    A(λ) = 1,5 x 105 [cm-1], were measured for the sample that had been post annealed at 500 deg C. The crystalline tungsten oxide films provides for a good switching capability in the NIR spectral range wile at the same time maintaining a high transmittance T(λ) in the visible spectrum.

  • 15.
    Alwan, Seif
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    The Effect of Fano Resonance on ExchangeInteraction in a DQD Junction with RashbaSpin-Orbit Coupling2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this work, we investigate electronic transport through a double quantum dot junction, where each dot couple to external localized spins. The junction is embedded in between two metallic leads,functioning as continues electron reservoirs. The double quantum dotjunction forms in the junction a bonding and anti-bonding state, muchresembling the electronic structure of a molecule, hence provides in-sight to such systems. Due to the nature of the parallel coupling weexpect a reduced tunneling through the anti-bonding state as a resultof destructive interference as the tunneling is provided multiple path-ways through the molecule. We predict that signature effects arisecorrelating the quantum observable to the effective exchange couplingbetween the localized spin moment and the electronic structure of theDQD. We expect the Fano resonance to disappear entirely when the anti-bonding state is localized and the transmission is carried purely through the bonding state. We further investigate the effects of in-clusion of Rashba Spin-Orbit coupling, allowing decoherence in thetransport. Here, a further degree of freedom is available and morecontrol of the quantum interference and hence the signatures in theexchange is allowed.

  • 16.
    Alwan, Seif
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Tunable Fano Resonance in Double Quantum Dot Systems2017Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
  • 17.
    Anastasiadis, Anastasios
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    A Monte Carlo simulation study of collimators for a high-spatial-resolution Gamma Emission Tomography instrument2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The present master thesis concerns a study of collimator designs for a high-spatial-resolution Gamma Emission Tomography (GET) instrument for used fuels utilizing Monte Carlo simulation codes. Designing a collimator for this purpose is a multilateral process that requires many interconnected and conflicting objectives to be taken into consideration. The purpose is to design a high-spatial-resolution GET system that combines in the best way the properties of a high detector count-rate, high photopeak to total spectrum ratio, low detector dead time and low leaking background radiation through the collimator material. As to achieve the best trade-off among these objectives, the GEANT4 and the Serpent 2 simulation codes were implemented. Used fuel contains various γ-ray emitting radionuclides and depending on the burnup history and cooling time their absolute intensities vary (i.e. for higher γ-ray intensity from the fuel, bigger collimator length is demanded). For this reason, Serpent 2 was used to produce long- and short-cooled fuel gamma emission spectra of low and high burnup. According to the obtained spectra, the collimator slit dimensions and material were determined. As far as the collimator length and material is concerned, the GEANT4 simulation toolkit was used to deal with shielding problems by applying the geometry splitting/Russian roulette variance reduction techniques. Serpent 2 simulations were performed in order to determine the transmitted signal intensity through the slit for various slit height and width dimensions. Finally, it was investigated the peak-to-total ratio change for different slit sizes and when a cavity structure was added along the slit length.

  • 18.
    Anastasiadis, Anastasios
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Calculation of γ-ray mass attenuation coefficients (μ/ρ) for different burnup values of UO2 nuclear fuels in a PWR simulated by Serpent 2 Monte Carlo code2018Independent thesis Advanced level (degree of Master (Two Years)), 10 HE creditsStudent thesis
  • 19.
    Anastasiadis, Anastasios
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Calculation of γ-ray source spectra for used LWR nuclear fuels2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The present project aims to provide the γ-ray source spectrum (the gamma energies and their intensities) for a nuclear fuel, given its physical dimensions, its enrichment and the detailed knowledge of the burnup history. In a nuclear reactor, the nuclide concentrations within the nuclear fuel change due to nuclear transmutation caused by neutron irradiation and due to the radioactive decay during and after the irradiation. This alteration in the fuel composition is simulated in this project with a burnup-mode simulation using the reactor physics code Serpent 2. A second Serpent 2 photon-mode simulation follows as to evaluate the γ-radiation spectrum from the respective nuclides produced in the first simulation. Finally, the γ-ray mass attenuation coefficients for selected energies are evaluated by combining the fuel elemental concentrations with the corresponding mass attenuation coefficients for fresh fuel based on NIST XCOM database. To facilitate the repeated evaluation of the γ-ray source spectrum, a custom-made MATLAB® function, GetEmissions, that initiates the Serpent 2 simulations was created. This function utilizes the user input data, which are the fuel dimensions, the fuel enrichment and the burnup history, as to automatically create an input for the Serpent 2 code. Afterwards, it executes burnup and photon simulations, and finally extracts the data sought for, which are the emitted by the fuel γ-ray energies and their intensities (γ-ray source spectrum). In addition, for the given fuel characteristics, the function provides the mass attenuation coefficient for a selected γ-ray passing the fuel. Using the GetEmissions function, the gamma spectra from ten nuclear burnup history cases representing a scan through low and high burnup and short, medium and long cooling times are calculated. The resulting top ten gamma energies are listed by absolute intensity, and information about the mother nuclide and the decay is provided.

  • 20.
    Andersson, Jennifer
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Determination of the Orbit and Dynamic Origin of Meteoroids2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    One method that can be used to identify the dynamic origin and specific parent bodies of Earth crossing meteoroids is the determination of the meteoroids’ orbital evolution. In this study, a Python-based program using the REBOUND software integration package to integrate meteoroid orbits backwards in time is developed. The program uses data from meteor observations made by the Swedish Allsky Meteor Network, and traces the distance and relative velocity between the meteoroid orbit and the orbits of selected parent body candidates backwards in time. The measure of these orbital differences is known as dissimilarity. The model is used to successfully reproduce the evolution of the Southworth-Hawkins dissimilarity criterion of the Annama meteorite and plausible parent body candidate 2014 UR116 presented by Trigo-Rodríguez et al (2015), as well as to determine plausible parent body associations of several meteors observed by the Swedish Allsky Meteor Network. Plausible parent bodies are presented in two new meteor cases, one of which confirms the parent body of the Geminid meteor shower.

    The model is concluded to be sufficiently accurate to motivate further use for meteoroid orbit integration purposes, and suggestions for future improvements are made. A new plausible parent body candidate for the Annama H5 meteorite is identified; the asteroid 2017 UZ44. In the case of one meteor event previously identified as a Perseid, the verification of the parent body is not successful using the developed model. In this case, no parent body candidate is found. Possible reasons for this are discussed. Moreover, the observational accuracy is found to be crucial if the program is to be used to study the meteor events observed by the network in detail, as the orbit has to be very well-constrained.

  • 21.
    Andersson, Joachim
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Dahlberg Vesterlund, Jesper
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Liu, Lollo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Simonsson, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Söderström, Niklas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Ulfsparre, Emma
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Optimerad energiprestanda genom fönsterbyte2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 22.
    André, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Benchmarking Physical Properties of Water Models2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

        Water is a fundamental part of life as we know it, and by that also a fundamental for biology, chemistry, and parts of physics. Understanding how water behaves and interacts is key in many fields of all these three branches of science. Numerical simulation using molecular dynamics can aid in building insight in the behavior and interactions of water. In this thesis molecular dynamics is used to simulate common rigid 3 point water models to see how well they replicate certain physical and chemical properties as functions of temperature. This is done with molecular dynamics program GROMACS which offers a complete set of tools to run simulations and analyze results. Everything has been automated to work with a python script and a file of input parameters. Most of the models follow the same trends and are valid within a limited temperature range.

  • 23.
    Aronson, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Physics Didactics.
    Gymnasieskolans bristande astronomiundervisning: hur lärares attityder påverkar undervisningen2010Student paper other, 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This paper is based upon a questionnaire and interviews with Swedish secondary school teachers (student of ages from 16 to 18). The purpose of the paper was to get a picture of teacher’s attitudes to astronomy in the physics courses and how this affects their teaching. The questionnaire showed that astronomy is the least prioritized field in physics in secondary school. Teachers seem to generally consider astronomy as the least important field and they spend little time teaching it, many teachers even exclude astronomy completely from their classes. Why astronomy has so low priority seems to have several reasons. Some of the more common reasons are that the curriculums does not prioritize astronomy, that teachers usually does not have very good knowledge in astronomy, that astronomy is not considered useful for high school studies and that astronomy often is taught at the end of the courses and therefore sometimes needs to be cut from the course because of time restraints. When the underlying causes for astronomy’s low priority have been uncovered a couple suggestions for solutions to the problems are presented. The paper also analyzes some of the problems with the astronomy part in the physics curriculums. They are vaguely and inconsequently written and this can lead to great differences in astronomy education from different teachers.

  • 24.
    Aronson, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Modelling reflected polarized light from exoplanetary atmospheres2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    I present numerical simulations of intensity and degree of polarization of light reflected by Earth-like exoplanets. The results are presented as a function of wavelength, and for a few different phase angles and a few different points on the planet. At this stage the aim is to show the working code and test a few different set ups of the star-planet system in order to find preferable configurations for observations. Not surprisingly, phase angle 90◦ shows the largest degree of polarization. For beneficial wavelength regions, visual light shows a larger overall degree of polarization, while NIR shows very clear absorption patterns in the degree of polarization, making detection of the atmospheric composition possible.

  • 25.
    Aðalsteinsson, Sigurbjörn Már
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Study of rare-earth oxy-hydrides as candidates for photochromic materials2019Student paper other, 10 HE creditsStudent thesis
  • 26.
    Back, Markus
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Investigation of the properties of thin films grown via sputtering and resistive thermal evaporation: an Ion Beam Analysis (IBA) study2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In this project, thin films are being manufactured by different methods in a thin film deposition set-up and subsequently characterized. This is done in order to determine if the set-up is capable of producing films of sufficient quality to be used for research purposes in the ion physics group of the division of applied nuclear physics at Uppsala University. Both copper and silver films are manufactured by magnetron sputtering deposition. Copper films are also manufactured by evaporation deposition. Deposition is made on Si(001) substrates. The films are analyzed with Rutherford Backscattering Spectrometry (RBS) and Time of Flight- Elastic Recoil Detection Analysis (ToF-ERDA). Results show that the deposition rate of the set-up is much faster compared to the one provided by the manufacturer of the set-up. The purity of the films i.e. the concentrations of the contaminants are found to be in an acceptable range for research applications with an average oxygen contamination of  and carbon contamination of  for sputtered copper films. Sputtered silver films were found to have an oxygen contamination of  and a carbon contamination of . Evaporated copper films were found to have an oxygen contamination of  and carbon contamination of . Traces of gold () were found exclusively in the sputtered films. Trace amounts of hydrogen could also be detected in both sputtered and evaporated films. The evaporated films are found to show lower contamination by oxygen than the sputtered films, but the manufacturing process employed in this study of evaporated films is not suitable to use for producing thin films of specific thicknesses as there is insufficient data to find a deposition speed. Overall, the set-up is capable of producing thin films with a sufficient quality for it to be used by the department when producing thin films for research.

  • 27.
    Balkeståhl, Li
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Nuclear Physics.
    Review of inclusive data for electron scattering on 3He at Jefferson Lab2010Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis reviews the inclusive data from experiment e89044 at JeffersonLab, Newport News, Virginia, USA. This experiment studied electron scat-tering on 3 He for beam energies up to 4 GeV. Data was taken at both forwardand backward angles with the same four-momentum transfer, namely Q2 be-tween 0.8 and 4.1 (GeV/c)2 . In this thesis I have investigated the behaviorof inclusive data with respect to some of the available variables and whatcuts to place on them to filter out events of interest.

  • 28.
    Barr, Johanna
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Improving Maintenance of Micro Hydropower Systems in Rural Nepal2013Student paper other, 10 credits / 15 HE creditsStudent thesis
  • 29.
    Baum, Sebastian
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    On the metastability of the Standard Model2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With the discovery of a particle consistent with the Standard Model (SM) Higgs at the Large Hadron Collider (LHC) at CERN in 2012, the final ingredient of the SM has been found. The SM provides us with a powerful description of the physics of fundamental particles, holding up at all energy scales we can probe with accelerator based experiments. However, astrophysics and cosmology show us that the SM is not the final answer, but e.g. fails to describe dark matter and massive neutrinos. Like any non-trivial quantum field theory, the SM must be subject to a so-called renormalization procedure in order to extrapolate the model between different energy scales. In this context, new problems of more theoretical nature arise, e.g. the famous hierarchy problem of the Higgs mass. Renormalization also leads to what is known as the metastability problem of the SM: assuming the particle found at the LHC is the SM Higgs boson, the potential develops a second minimum deeper than the electroweak one in which we live, at energy scales below the Planck scale. Absolute stability all the way up to the Planck scale is excluded at a confidence level of about 98 %. For the central experimental SM values the instability occurs at scales larger than ~ 10¹⁰ GeV.

    One can take two viewpoints regarding this instability: assuming validity of the SM all the way up to the Planck scale, the problem does not necessarily lead to an inconsistency of our existence. If we assume our universe to have ended up in the electroweak minimum after the Big Bang, the probability that it would have transitioned to its true minimum during the lifetime of the universe is spectacularly small.  If we on the other hand demand absolute stability, new physics must modify the SM at or below the instability scale of ~ 10¹⁰ GeV, and we can explore which hints the instability might provide us with on this new physics.

    In this work, the metastability problem of the SM and possible implications are revisited. We give an introduction to the technique of renormalization and apply this to the SM. We then discuss the stability of the SM potential and the hints this might provide us with on new physics at large scales.

  • 30.
    Bengtsson, Kristoffer
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Broadening of spectral lines in the Gaia-ESO survey2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Analyzing stellar spectra plays a big role in understanding the evolution of our galaxy. Having good data for spectral line properties is very important when analyzing these spectra. One part of the Gaia-ESO public spectroscopic survey (GES) is to gather data for spectral line properties from stellar spectra. The scope of this project is to study one of these properties, the spectral line width caused by collisional broadening by hydrogen. Collisional broadening by hydrogen occurs when a hydrogen atom collides with a particle. The goal of this project is to successfully calculate the collisional spectral line broadening of iron lines where new data is missing from the GES using modern quantum mechanical calculations. These calculations are done using the ABO theory, which is more advanced than previously established theory.A table of Fe-I (Neutral iron) spectral lines without collisional broadening data in the GES has been provided. Using the ABO theory and the accompanying ABO cross section calculator code, estimates of collisional broadening by hydrogen have been calculated for these lines. The new calculations predict that the line width of the spectral lines are typically twice as large compared to older estimates calculated using simpler theory. This new data can be expected to improve stellar spectrum analysis in the Gaia-ESO survey spectra.

  • 31.
    Bengtz, Oskar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Chemical signatures of the first stars2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The first stars are something many scientists are curious about. How did they formand how did the universe look like at that time? These stars however probably died along time ago, or are at a distance too far away from us to be observable. If these starsexploded and formed supernovae there might be stars observable today that formed fromthe ejecta of these supernovae. Models of nucleosynthesis in the first stars may potentiallybe used to infer parameters of progenitor supernovae from chemical abundances in old,metal-poor stars. This thesis aim is to find out how precise these abundances need to beto achieve a certain precision in the supernova parameters. This is done by perturbingthe abundances for one element at a time in four different stars and see how the recoveredsupernova parameters change. The first conclusion is that it isn’t necessarily the sameelements that are important for determining the supernova parameters in all stars, andif there is one thing that decides which elements are important it would be the star’smetallicity. The stars HE1327-2326 and HE0107-5240 metallicites are close to each other,with [Fe/H] < -5.0 and [Fe/H] = -5.3 respectively, and behaved similarly, the elementmost important in both stars was nitrogen. The star SMSS0313-6708, [Fe/H] < -7.3, hadmore elements that changed the parameters, the most important beeing C, O and Ca.The star CS 31028-001, [Fe/H] = -2.9, also had many elements that were important, andsome of them are Na, K and Ni.

  • 32.
    Bengtz, Oskar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Physics Didactics.
    Student-generated representations in Algodoo while solving a physics problem2018Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Physics teachers are often faced with the difficult task of representing abstract, formally-defined properties of the physical world (such as forces or energy) for students in a way which goes beyond equations, graphs, and diagrams. In this study, I investigate two cases of university students solving a physics problem while using the digital software, Algodoo, on a large touch screen to examine how students might naturally leverage such technology to create such representations of their own. I find that as student draw scenes in Algodoo, they tend to prioritze a degree of resemblance to the physical world which goes beyond the formal treatment of problems they might have been taught in physics classes. Additionally, as the students recruit physics equation into their solution of the problem, they appear to use Algodoo as a conceptual check for the numerical answer they calculate on the normal whiteboard. In this way - and as has been hypothesized in previous research - I see the potential for Algodoo and similar digital learning environments to act as a bridge between students’ conceptual intuitions of the physical world and the more formal, mathematically-based descriptions used in physics.

  • 33.
    Ben-Shahar, Maor
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    The double-copy method for supergravity amplitudes2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The double-copy construction enables the calculation of scattering amplitudes in theories of gravity by combining amplitudes from gauge theories. It relies on obtaining numerators that obey a duality between color and numerator factors, called color-kinematics duality. This construction is reviewed, along with the spinor-helicity formalism for onshell states and supersymmetry in amplitudes. Using generalized unitarity, a one-loop amplitude is verified from literature for a N = 2 theory obeying color-kinematics duality. This amplitude, along with a one-loop amplitude for a N = 0 theory are combined with the double copy in order to produce one-loop amplitudes from homogeneous supergravities. The one-loop divergence is studied with the methods of counterterm analysis, that is, operators necessary to cancel the on-shell matrix element of the divergence are identified for the amplitudes studied. It is interesting to note that all vectors produced from the double copy behave in the same way, that is, have the same divergence, for the four special cases of the magical supergravities. Furthermore, one of the counterterms vanishes for these four special cases, which is likely related to the enhanced symmetry that these theories posses.

  • 34.
    Bergstedt, Josefine
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    How to construct a 3D model of the planetary nebula NGC 6781 with SHAPE2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The objective of this work is to reconstruct a 3D model of the planetary nebula (PN) NCG 6781 using the computer software SHAPE.

    A planetary nebula forms when specific types of stars, with masses between 0.8-8 M⊙ (where ⊙ is solar masses) end their lives. In the last evolutionary stage of these stars radial pulsations and a fast wind blows away the spherical, outer layers of the star until only the core of the star remains. The core will cool off and finally becomes a so called white dwarf which is surrounded by a shell of the ejected gas and dust. This expanding shell of glowing ionized gas and dust is called a planetary nebula. The word "nebula" is Latin for mist or cloud and the name planetary nebula came in the 1780’s since these objects looked like large gaseous planets when observed. Planetary nebulae exist in many and various shapes, from bipolar to multistructured. It is anticipated that the fast wind in combination with radiation from the star affects the formation of the planetary nebulae. Exactly how these processes work and what mechanisms that cause the outer, spherical layers of the star to adapt the spectacular and multi-structured shapes seen in planetary nebulae is not well known.

    SHAPE is an interactive computer program that has been developed during the last few years and is a tool used by astrophysicists. In SHAPE, 3D models of different astronomical objects can be set up in order to understand and try to determine their morphology, density and temperature distribution and velocity field. SHAPE is particularly suited for planetary nebulae. The aim of a 3D model is that it provides an opportunity to rotate the object and view it from different angles and determine how the velocity field affects the emission from the nebula. This gives new insights to the structure of the object and its distribution, which may contribute to increased knowledge about the mechanisms that control the formation of planetary nebulae.

    In this work I have modeled the planetary nebula NGC 6781. I compare my model to previous attempts at determining the morphology of the nebula and to recently obtained observations of the carbon monoxide (CO) emission from the nebula. The model of NGC 6781 appears to be a hollow cylinder with inner radius 38” and outer radius 60” and with a depth of 117”. The model is a bit extended at the waist so it gets the shape of a barrel. The cylinder is tilted forward 21 degrees and rotated to the left with 20 degrees. The expanding gas within the nebula is moving radially outwards with the relation v=0.26·r, where r is the distance from the origin and the gas has a velocity of ∼ 16 km/s at the rim of the cylinder. The model reproduces the observed CO emission well and in particular the velocity, temperature and density distribution of the molecular gas. The velocity, temperature and density distribution agrees with typical values found for PNe and with what could be expected if NGC 6781 has evolved from an AGB star.

    It is hard to estimate exact errors for the different parameters since they are strongly dependent on one another. It seems like the velocity and den- sity parameters are those most sensitive to variations and these causes the biggest changes in the model, when altered. 

  • 35.
    Binggeli, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Simulating the spectra of galaxies in the reionization epoch: Constraining the escape fraction of ionizing photons2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The cosmic reionization represents a fundamental yet poorly understood phase transition in the evolution of our universe. The most promising theory is that the ionizing radiation from young hot stars in star-forming galaxies drove reionization, but much information about the number of galaxies and the escape fraction of ionizing radiation from galaxies is still missing. In this thesis, I discuss a technique for estimating the escape fraction of hydrogen ionizing radiation from galaxies in the reionization epoch. The method utilizes the power law slope of the UV continuum and the equivalent width of the Balmer beta emission line to try to estimate the escape fraction of a galaxy from its spectrum without ever directly observing any ionizing radiation. The technique is applied to simulated galaxies from large scale cosmological simulations.I find that the method works for estimates of the escape fraction of dust free simulated galaxies. It is possible to distinguish between galaxies with escape fractions 0.0, 0.5, 0.7 and 0.9 when no dust is added to the galaxies. I also show that the method works regardless of choice of numerical assumptions and assumptions about stellar evolution in the models. Lastly, I show that the addition of dust to the galaxies can introduce an ambiguity to the estimated escape fraction, and that this may reduce the estimation into just being between high or low escape fractions. The results also show that equivalent widths of the Balmer beta emission line larger than approximately 100 Ångströms are seen only in galaxies with escape fractions consistent with zero. The addition of dust and its effect on the spectral features used in the technique allows for an estimation of the average dust content. I find that the galaxies contain low amounts of dust, with a highest average dust attenuation in the visual of A=0.4-0.6 magnitudes.

  • 36.
    Binggeli, Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Stellar libraries for population synthesis: A comparative study of the MARCS and ATLAS9 theoretical stellar libraries2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Stellar population synthesis is a tool for modelling galaxies and their spectral energy distributions. By combining the spectra of every star within a galaxy, it becomes possible to form the spectrum of the galaxy as a whole. This requires a large collection of stellar spectra which, ideally, contains spectra for every kind of star in the model galaxy. To contribute to the development of stellar population synthesis and model atmospheres, I examine two such collections of stars, the MARCS and ATLAS9 theoretical stellar libraries. I compare 18 spectra of model stars for which both libraries have performed calculations. Stars with three different temperatures were chosen (8000K, 4500K and 3500K). For each temperature, three values of metallicity and two values of effective gravity were chosen. I find a mismatch in the spectra of the medium and low temperature model stars (4500K and 3500K), in addition, a difference in molecular features (~7000Å) is found in the 3500K low metallicity models ([Me/H]=-2.5). I conclude that this difference is caused by missing molecular opacities for the calcium hydride (CaH) molecule in the ATLAS9 library. Four possible causes of the overall mismatch are discussed: the temperature structure of the models; the geometry of the models; and partition functions used for the calculation of the models. I conclude that none of these four sources could produce the mismatch. This leaves room for further investigation into the cause of the mismatch.

  • 37.
    Björk, Kevin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Embedding inflation in string theory2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    We introduce slow-roll inflation in string theory on both a conceptual level and a detailed one. In order to do this we first briefly review important concepts of inflation and string theory. We then reconstruct models of string inflation in the so-called Racetrack scenario for two different cases where the difference being the number of Kähler moduli used as inflaton. Furthermore, we briefly relate our results to the more recent discussion on whether AdS/dS solutions actually exist in string theory. In this instance our results seem to indicate that uplifting is a crucial component to obtain AdS/dS solutions.

  • 38.
    Björk, Kevin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Fluctuations in the CMB through inflation2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The goal of this project is to gain a better understanding of the temperature fluctuations observed in the CMB. This goal is reached with the aid of a literature study. The report touches upon the origin of the CMB as well as how it is measured, mentioning and explaining relevant concepts such as recombination, photon decoupling, black body radiation, angular power spectrum etc. It is also specified that the temperature of the CMB is not uniform but varies slightly. The fact that these fluctuations show inhomogeneities at the early universe is emphasized as well as the need for a satisfying theory that explains said fluctuations. By presenting and employing inflation theory in combination with quantum mechanics, we show how such a theory can be obtained. Through extensive calculation we show how the primordial power spectrum for zero-point fluctuations during inflation is obtained and how it can be related to the time of recombination through a transfer function, thus explaining the existence of fluctuations in the CMB.

  • 39.
    Bliem, Pascal
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Tunable perpendicular anisotropy inδ-doped Co/Fe-V superlattices2017Student paper other, 10 credits / 15 HE creditsStudent thesis
  • 40.
    Bliersbach, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Hydrogen diffusion in nano-sized materials: investigated by direct imaging2011Independent thesis Advanced level (professional degree), 40 credits / 60 HE creditsStudent thesis
    Abstract [en]

    The kinetics of interstitial hydrogen are of great interest and importance for metal-hydride storage, purification, fusion and fission reactor technology, material failure processes, optical sensors for hydrogen gas and many other technologies. In particular nano-sized materials motivate fascinating applications and scientific questions. If hydrogen is absorbed in vanadium it alters the band structure around the Fermi energy. These modifications of the band structurelead to a change in the absorptance of vanadium which are in first order approximation proportional to the concentration. We present a methodto quantify chemical diffusion of hydrogen in nano-sized materials.The induced changes in the absorptance of vanadium hydride (VHx) thin-films are observed visually and in real-time as a function of position.Concentration profiles and their evolution in time, during chemicaldiffusion, were measured down to a hydrogen content corresponding tojust a few effective monolayers, randomly distributed within VHx. For concentrations reached via phase transitions distinct diffusional behavior was found, where a diffusion-front, a strong concentration gradient, migrates in the direction of the diffusive hydrogen flux. The results show that decreased size strongly influences the energy landscape and reveal different rate limiting steps for absorption and desorption.

  • 41.
    Blom, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Characterization of γ-rays at MAST2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The γ-ray characterizing possibility of the neutron collimated flux monitor (in short, Neutron Camera) at the Mega Ampere Spherical Tokamak (MAST) is explored. Typically used to monitor neutron emission, the Neutron Camera has excellent neutron/γ-ray discrimination properties and thus presents the opportunity to measure spatially and temporally resolved γ-ray emission - a possibility of an additional fusion diagnostics method with already existing equipment. An Online Data Analysis (ODA) code was used to analyze the data on γ-rays from several plasma discharges with similar plasma parameters. A high statistics temporal distribution of the γ-ray emission and a lower statistics spatial distribution were analyzed. However, the low energy resolution and range for the Neutron Camera γ-ray measurements revealed few conclusive results on the origin of the higher energy γ-rays. Detection systems with higher energy resolution and range are suggested for an extensive analysis of γ-ray emission at MAST Upgrade.

  • 42.
    Boirot, Milo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Implementation of low-energy PIXE at the new scattering chamber of the 350 kV implanter2019Independent thesis Advanced level (degree of Master (One Year)), 10 HE creditsStudent thesis
    Abstract [en]

    In this work, a new setup for low-energy Particles Induced X-Ray emission (LE-PIXE) was developed at the third beamline of the 350 kV implanter.  First, we implemented a new X-Ray detector in the chamber. Then, we compared the method with other X-ray based techniques such as, X-ray Fluorescence (XRF), Energy Dispersive X-Ray Spectroscopy (EDX) and high-energy PIXE . An analysis of the strengths and weakness of each technique will be given. To complete the experimental work, an important theory part is provided to introduce the main phenomena taking place during the experiments, covering from the main theory of the ionization of atoms to the cross section and attenuation principle for PIXE and RBS.  Likewise an analysis of the limitation and of the possibility of low-energy PIXE through the detection limits measured on Fluorine and Oxygen samples will be carried out. The major goal is to be able to make a new statements on low-energy PIXE method following new theoretical models and better equipment.

  • 43.
    Book, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, FREIA.
    1kW Class-E solid state power amplifier for cyclotron RF-source2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis discusses the design, construction and testing of a highefficiency, 100 MHz, 1 kW, Class-E solid state power amplifier. The design was performed with the aid of computer simulations using electronic design software (ADS). The amplifier was constructed around Ampleon's BLF188XR LDMOS transistor in a single ended design. The results for 100 MHz operation show a power added efficiency of 82% at 1200 W pulsed power output. For operation at 102 MHz results show a power added efficiency of 86% at 1050 W pulsed power output. Measurements of the drain- and gate voltage waveforms provide validation of Class-E operation.

  • 44.
    Book, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Temperature and concentration dependence of hydrogen diffusion in vanadium measured by optical transmission2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Hydrogen diffusion is investigated in a 50 nm film of vanadium and a vanadium superlattice. Diffusion constants for three different temperature and pressure pairs are determined for the 50 nm film. The diffusion constants for the temperature and pressure pairs are determined to be 4.5 $\pm$ 0.1 $\cdot 10^{-5} \text{ cm}^{-2}$ at 463 K and 0.05 H/V, 5.6 $\pm$ 0.1 $\cdot 10^{-5} \text{ cm}^{-2}$ at 463 K and 0.12 H/V and 8.0 $\pm$ 0.2 $\cdot 10^{-5} \text{ cm}^{-2}$ at 493 K and 0.05 H/V.

    The temperature and concentration dependence of the diffusion constants are determined. A concentration dependence of the diffusion constant is found with a higher rate of diffusion for a higher hydrogen concentration. The activation energy of chemical diffusion is determined to be 0.38 $\pm$ 0.03 eV.