Heat transport by phonons and magnons in crystals due to a local perturbation in temperature is described by the Boltzmann transport equation. In this project a one phonon one magnon system was studied in a one dimensional rod with reflective boundaries. Using the splitting algorithm the problem was reduced to a transport and collision term. The resulting stabilization time for a initial phonon and magnon distribution and the respective temperatures at equilibrium was calculated. This study shows how energy propagates in crysials and gives further understanding of how the coupling of phonons and magnons affect heat transport.

The main focus of this project was to prepare transparent and conductive electrodes (TCEs). TCEs were made out of multi-walled carbon nanotubes (MWCNTs), reduced graphene oxide (rGO), and polyvinylpyrrolidone (PVP). Based on the theoretical aspect, MWCNTs has emerged as a promising nanofiller in the polymer matrix due to its high electrical conductivity. As a nanofiller, MWCNTs were used with a small ratio of rGO with PVP as a polymer matrix in this project to prepare TCEs having low sheet resistance with high transparency. An appropriate amount of PVP has been shown to be a good combination with MWCNTs and rGO in the solvent to keep MWCNTs dispersed for a long time. Carboxyl group (-COOH) functionalized MWCNTs (FMWCNTs) was produced in a controlled oxidative procedure due to enabling good dispersion of FMWCNTs in water and ethanol solvents. In contrast, water dispersible rGO was chemically prepared by using GO and sodium borohydride where GO was produced from graphite by using improved Hummer's method. Drop casting and spray coating methods were applied to fabricate TCEswhere only water was used as the solvent for drop casted TCEs and a mixing ratio of water and ethanol was 70:30 as solvent for spray coated TCEs. It was also determined in this project that the spray coating method was more suitable for preparing TCEs rather than thedrop casting method due to easy fabrication, large area coating possibility, and the smoothness of the coated film surface. The sheet resistance was obtained as 5026 Ω/ ⃣  where the transparency was 65% in the case of the drop casted electrode for the ratio of rGO:FMWCNTs:PVP was 1.2:60:1 with 0.02 mg FMWCNTs. In the case of spray coated electrode at the same ratio of rGO:FMWCNTs:PVP, the sheet resistance was measured as 5961 Ω/ ⃣  where the transparency was 73%. But in the case of 60:1 mass ratio of FMWCNTs:PVP with 0.02 mg FMWCNTs, the sheet resistance was 7729 Ω/ ⃣  and transparency was 77% for spray coated electrode. So, it is clear that the sheet resistance was improved by adding a small mass ratio of rGO with FMWCNTs:PVP.

Deformations of nuclear fuel assemblies have been observed in nuclear power plants since the mid-90s. Such deformations are generally called bowing effects. Fuel assemblies under high irradiation undergo growth and creep induced by high loading forces and low skeleton stiffness of the assemblies which gives permanent deformations and modifies moderation regions. Hence, giving an unpredicted neutron flux spectrum, power distribution, and isotopic concentrations in the burnt fuel. The aim of this thesis is to study the effects of local fuel bowing in terms of power distribution and isotopic composition changes through simulations of the reactor core.  The reactor is simulated with realistic bowing maps and previous deterministically simulated realistic fuel data from a present reactor by deploying the Monte Carlo method using the nuclear reactor code Serpent 2. Two subparts of a full reactor core with fuel from separate fuel cycles are investigated in 2D using burnup. To quantify the impact of the bowing, the change in power distribution and the induced isotopic composition change are calculated by a relative difference between a nominal case and a simulation with perturbed fuel assemblies. The results are presented in colormaps, for visualization. The isotopic composition for U235, U238, Pu239, Nd148, and Cm244 are investigated. Also, statistical uncertainty estimations in the composition of the depleted fuel are done by multiple calculations of the same geometry while changing the seed of random variables in the Monte Carlo calculation. The mean value and the standard deviation in the mass density of U235 and Pu239 are calculated for two pins together with histograms with a normal fit for each case to clarify the mathematical distribution of the calculations.  The simulations performed in this thesis have detected clear impacts of the reactor behavior in terms of power distribution and isotopic composition in the burnt fuel introduced by the bowing. Assembly perturbations of about 10 mm may locally introduce a 10 % relative difference in power density and U235 content between the nominal and the bowed case at 15 MWd/kgU burnup. The power and the isotopic composition changes agree with expectations from the bowing maps.

High power laser pulses can be a threat to sensors, including the human eye. Traditionally this threat has been alleviated by colour filters that blocks radiation in chosen wavelength ranges. Colour filters’ main drawback is that they block radiation regardless of it being useful or damaging, information is removed for wavelengths at which the filter protect. Protecting the entire wavelength range of a sensor would block or strongly attenuate the radiation needed for the operation of the sensor. Sol-gel glasses highly doped with Pt-Acetylide chromophores have previously shown high optical quality in combination with efficient optical power limiting through reverse saturable absorption1. These filters will transmit visible light unless the light fluence is above a certain threshold. A key design consideration of laser protection filters is linear absorption in relation to threshold level. By increasing chromophore concentration the threshold is lowered at the expense of higher linear absorption. This means that the user’s view is degraded through the filter. Adding small amounts of gold nanoparticles to the glasses resulted in an increase in optical power limiting performance. The optimal concentration of gold nanoparticles corresponded to a mean particle distance of several micrometers. The work in this licentiate thesis is about the characterization and explanation of this effect. The glasses investigated in this work were MTEOS Sol-Gel glasses doped with either only gold nanoparticles of varying shape and concentration, 50mM of PE2-CH2OH codoped with gold nanoparticles or 50mM of PE3-CH2OH codoped with gold nanoparticles. The glasses only doped with gold nanoparticles showed high optical power limiting performance at 532nm laser wavelength, but no optical power limiting at the fluences tested at 600nm. The PE2-CH2OH glasses codoped with gold nanoparticles showed an enhancement of optical power limiting at 600nm for the low gold nanoparticle concentration glasses. The enhancement was weakened or not present for higher concentrations. A similar enhancement above noise level for the PE3-CH2OH glasses was not found. A population model is used to give a qualitative explanation of the findings. The improvement in optical power limiting performance for the PE2-CH2OH glasses is explained by the gold nanoparticles helping to more quickly populate the highly absorbing triplet state during the rising edge of the laser pulse by enhancing two-photon absorption. The lack of any marked enhancement for the PE3-CH2OH glasses is explained by the PE3-CH2OH chromophore already being of sufficiently high performance to quickly populate the highly absorbing triplet state during the rising edge of the laser pulse. Further work is necessary to validate this model against other chromophores and improving its quantitative predictive power.

Proteins are one of the most important molecules in biology. The wide range of functions of different proteins is also important for medical physics. Proteins are assembled by amino acids. These amino acids are connected by peptide bonds to form a protein. The function of a protein is decided by the composition and configuration of peptides, amino acids and their peptide bonds. Successful experiments with Xray Free-electron laser has lead to progress in structural biology, however there is still a need to crystallized samples in these experiments. In this project we have investigated three amino acids. These three amino acids are included in several protein that are hard to crystallize, glycine, valine and alanine. We have investigated their separate interatomic bonds by performing density functional calculations and evaluating the susceptibility of the bonds breaking in a typical time range of Xray Free-electron laser pulses. The results shows the fast dissipation of hydrogen atoms, bond shifting within the molecules during certain ionization degrees and the dissociation of the protein backbone after 20 fs.

A quantum mechanical state may be transferred between locations using quantum teleportation.Specically information encoded in the polarized state of a light pulse maybe teleported onto the collective spin state of an ensemble of atoms. This thesis providesa theoretical framework for achieving such a teleportation protocol experimentally.

Serial Femtosecond X-ray crystallography (SFX) is a rapidly growing experimental technique by which the structure of a crystalline sample may be determined. The X- rays arrive at the sample in pulse trains of the order of femtoseconds. Each X-ray pulse train hits a unique crystal at a random orientation and produces a diffraction pattern on the detector and series of patterns is obtained, which is the reason for the denomination "serial". Here, the radiation damage done to a sample during an SFX experiment was studied by simulating diffraction patterns including damage. Throughout, a model reference structure in the form of a reflection list was used to simulate patterns. The aim was to minimise the effects of damage through a correction based on available damage data. Firstly, a simulation case with made-up damage data was performed. The made-up data was used to modify the structure factors such that they would appear damaged. After structural reconstruction, the same data was used to correct for the damage. This was done as a validation of the method pipeline. Secondly, a more realistic case, with actual simulated damage data and a distribution of incident intensities was carried out. The expectation value of the distribution was used to correct for damage. It is found for both cases that the damage correction improves the agreement between simulated data and the original model. This is a first step toward successfully correcting for radiation damage which would be a big step forward for SFX.

Clinical heavy ion beams provide the most accurate means of external radiation treatment of tumors available. The study of energetic heavy ions on individual cells have been hampered by shortcomings in available detector technology. The fluorescence nuclear track detector developed by the Landauer Inc. is a small chiplike detector with all the properties needed for these kinds of studies. It is biocompatible, autoclavable, does not require post-irradiation chemical processingand allows the readout of a sufficient number of physical parameters for the determination of a particle’s radiobiological and physical properties. Previous studies in clinical spread-out Bragg peaks have shown a discrepancy in what is detected to what is seen in Monte Carlo radiation transport simulations. While the fluence of heavy primary ions agrees to within one percent, the detection of fragments is underestimated by at least an order of magnitude. In this thesis the performance of the track-recording has been assessed for light ion fragmentsfrom hydrogen, helium and carbon primary particles in physically optimised spread-out Braggpeaks. The underestimation of light ion fragments for carbon beams, mentioned in previousstudies, was reproduced. The underestimation of light ion fragments is prevalent also for helium primary particles. No significant amount of lost tracks are seen in hydrogen beams. The analysis verifies the hypothesis that the detection of large angle trajectories for light ion fragments is not a principal limitation of the detector. The underestimation most probably stems from some limiting features of the readout and image analysis procedure.

In this project laser absorption spectroscopy was performed on a flame in a Fabry-Pérot cavity, using an optical frequency comb. Optical frequency comb spectroscopy is a technique that allows broadband ultra-sensitive detection of molecular species in gas phase. Optical frequency combs are generated by femtosecond mode-locked lasers, which generate short pulses and whose spectrum consists of a comb of sharp laser lines covering a broad spectral range. Doing spectroscopy with optical frequency combs can hence be compared to measurements with thousand of synchronised continuous wave lasers simultaneously, which enables broadband sensitive measurements in short acquisition times. A Vernier spectrometer uses the filtering ability of the cavity to allow sequential transmission of parts of the frequency comb spectrum. Its technical simplicity and robustness make it a good candidate for measuring in turbulent environments. The aim of the project was to implement continuous-filtering Vernier spectroscopy in a setup for measuring absorption spectra in air and in a flame. This was done by using an Er:fiber femtosecond laser emitting in the near-infrared wavelength range and a Fabry-Pérot cavity containing the flame. The cavity, which consists of two highly reflective mirrors, lets the light of the comb interact with the molecules in the flame for each of the many round-trips it perform; thus increasing the sensitivity to absorption. An active locking mechanism was implemented to stabilize the coupling of the optical frequency comb to the cavity. The locking allowed multiple measurements to be averaged which reduced noise. A galvanometer scanner was added to the system which was used to measure a broad part of the comb spectrum. Hot water absorption lines were detected in the swept comb spectrum and a candidate absorption peak for OH absorption was recorded. The spectrometer today has opportunities for improvements. A frequency calibration should be implemented which is essential for making estimates of reactant/product concentrations in combustion processes.

The recent discovery of Cr4AlB4, a laminated ternary metal boride belonging to the family of layered MAB-phases, where the transition metal boride layers are interleaved by an A layer, has spurred theoretical investigation for novel M4AlB4 phases. In this study, first-principles calculations were applied in order to investigate the thermodynamical stability and mechanical properties of M4AB4 where M = Cr, Hf, Mo, Nb, Ta, Ti, V, W, Zr while the A layer was kept fixed as Al. The thermodynamical stability calculations validate the recently discovered Cr4AlB4 phase’s stability and suggest the neighboring phase Mo4AlB4 to be stable. Additionally, the phases Mo3AlB4, Mo2AlB2, Ti4AlB4 and Ti2AlB2 indicates phases close to stable with a formation enthalpy within the range of 0 < ∆H < 25 meV per atom compared to competing phases. Hence dynamical stability investigations were carried out, which indicates Mo4AlB4 to be dynamically stable. The stability of Mo4AlB4 does encourage synthesizing attempts to be kept in mind as a future project. Phase stability trends of the 111, 212, 314 and 414 compositions were discovered, where a 212, 314 and 414 composition is seen to be more stable for an M-element with lower electron configuration. Furthermore, the mechanical properties of the 414 compositions were investigated by systematically straining the unit cell in different directions. The bulk-, shear- and Young’s-modulus were derived and are presented, where Ti4AlB4 demonstrates values similar to the commended Ti2AlC MAX-phase. Finally, ductility plots are presented which purposes a linear trend between the elements of group IV, V and VI. Based on the results, further studies with a focus on the temperature and magnetization’s impact on the stability and mechanical properties are suggested.