The KM3NeT neutrino telescope, located presently at two different sites in the Mediterranean Sea, consists of two neutrino detecors As the telescope is still being built, the calibration is fully...Show moreThe KM3NeT neutrino telescope, located presently at two different sites in the Mediterranean Sea, consists of two neutrino detecors As the telescope is still being built, the calibration is fully underway. This research focuses on four potential biases present in the astrophysical focused part of the detector, ARCA. Muon light, both detected and reconstructed from simulations and $^{40}$K decay being used to determine the size of those biases. It is found that the PMTs shadowed by the titanium collar on the DOM show a different bias dependent on what hemisphere they are located. Furthermore it is found that the different gel transperacy in the DOMs causes different efficiencies, and that the new PMTs show lower efficiencies than the old PMTs.Show less
The unification of general relativity and quantum mechanics has been a persistent challenge in the field of physics. This study introduces a design for a milligram-scale gravity source, termed the...Show moreThe unification of general relativity and quantum mechanics has been a persistent challenge in the field of physics. This study introduces a design for a milligram-scale gravity source, termed the Gravity Propeller. When coupled with the Magnetic Zeppelin, a gravity detector of comparable scale, it could potentially enable the measurement of gravitational interactions between two milligram objects. This measurement could provide insights into the unification of general relativity and quantum mechanics. The propeller, composed of two sets of Meissner levitated magnets connected by a stick, is designed to levitate within a type I superconducting trap and rotate to create a variable gravity potential. This research confirms the levitation of the propeller and demonstrates several optimizations, for instance, the minimization of damping. However, the rotation of the propeller is yet to be accomplished.Show less
In this project, the simulation software MRI2D was developed. It is a program that allows students to simulate the motion of spins during the magnetic resonance imaging experiment. Already...Show moreIn this project, the simulation software MRI2D was developed. It is a program that allows students to simulate the motion of spins during the magnetic resonance imaging experiment. Already available tools did not model multiple spins rotating to image tissues. Besides filling this niche, other design requirements were taken from existing educational tools. All requirements have been met. MRI2D is open-source software and can be downloaded for free. It comes with a manual for downloading and installing and three example exercises directly for classroom use. MRI2D is ready to now be implemented in education. Further development suggestions are given.Show less
Transition metal dichalcogenides (TMDs, MX2) are Van der Waals materials with properties such as the band structure depending on chemical structure and the number of layers. Low energy electron...Show moreTransition metal dichalcogenides (TMDs, MX2) are Van der Waals materials with properties such as the band structure depending on chemical structure and the number of layers. Low energy electron microscopy (LEEM) provides a manner of characterizing TMDs, by controlling the landing energies at which electrons reach the desired sample and measuring the reflection of the electrons. Besides real space imaging, our LEEM instrument is able to image reciprocal space, which is especially interesting to the characteristic hexagonal lattice of TMDs. This thesis will discuss a number of energy-resolution limiting factors. One of these factors is the energy distribution of electrons incident on the sample. It will discuss a method to correct for this energy dispersion and use it to decrease noise in electron reflectivity spectra. Also, fluctuations in electron current will be discussed and corrected for. Further, this thesis will examine oxidation of TMDs, as the rate of oxidation and impact on properties differs greatly depending on the specific composition of the TMD. It will discuss methods of exfoliating TMDs in vacuum, i.e. in situ, and show successful exfoliation in vacuum of around 10−6 mbar inside the LEEM. Also, the research will study exfoliation of Si/SiO2 substrates with gold evaporated to produce large flakes of few-layer TMDs. This yielded MoS2 few-layers flakes of up to 100 microns. The findings in this study regarding enhanced energy resolion in LEEM measurements of TMDs and improved techniques for TMD exfoliation will help the progress in understanding and characterization of TMD materials.Show less
Recent developments in the field of quantum optics have observed fine spectra in Fabry-P\'erot microcavities that can be substantiated with theory. This thesis describes the development of a...Show moreRecent developments in the field of quantum optics have observed fine spectra in Fabry-P\'erot microcavities that can be substantiated with theory. This thesis describes the development of a software that calculates the fine spectrum of a microcavity. A rotational-symmetric system is considered, with perfectly-reflecting mirrors. Paraxial theory states that these cavities have resonant modes in the form of scalar Laguerre-Gauss functions. Nonparaxial theory has added 2 scalar and 1 vector correction to the resonance frequencies. We use an object-oriented approach to propagate field profiles through a cavity with the help of Fourier transforms. Some numerical integration and interpolation tricks are used in the computations. Nonparaxial phase delays are compared to theoretical predictions and a first step is made to finding the eigenfunctions of a cavity by modal decomposition. The software only provides scalar corrections and needs improvement in some areas, but shows promising results for the scalar correction. It could potentially lead to more advanced extensions, like a composite cavity which can help experimentalists to understand more complex resonance spectra.Show less
A design was made for a flow injection manifold to inject gas into the flow test model of the TECH microwave plasma reactor. The manifold incorpo- rates separate inlets for the injection of purely...Show moreA design was made for a flow injection manifold to inject gas into the flow test model of the TECH microwave plasma reactor. The manifold incorpo- rates separate inlets for the injection of purely poloidal or mixed toroidal and poloidal flow into the toroidally shaped TECH reactor. Numerical simulations were performed on prospective injection geometries to verify the compliance of the produced velocity field with requirements on the uniformity of the flow and the relative size of the poloidal and toroidal flow components for each input. Modifications to the design were in- cluded to allow for 3D printing of the injection manifold. It was found that the final design for the injection manifold satisfies the uniformity re- quirements when an equal flow is provided to both inputs, but not when flow is provided to the poloidal input alone.Show less
Superconductivity is a macroscopic quantum phenomenon based on a transition from a fermionic electron system to a bosonic condensate of electron pairs. This condensate is characterized by two...Show moreSuperconductivity is a macroscopic quantum phenomenon based on a transition from a fermionic electron system to a bosonic condensate of electron pairs. This condensate is characterized by two length scales, λ and ξ, which separate superconductivity in a 3D limit (physical system size larger than intrinsic length scales) from lower dimensional structures. Although superconductivity is well studied in both the 3D and 2D limits, little is known about ‘fractional dimensional’ systems, exhibiting a non-integer dimensionality induced by the geometry. This thesis explores the behaviour of planar Josephson junctions featuring electrodes structured as Sierpiński carpet fractals (Hausdoff dimension ∼ 1.8). Although the magnetic response of these junctions is dominated by flux-trapping effects, the underlying interference pattern is unconventional and cannot be described by simulations based on the electrode geometry. This warrants further study of the flow of supercurrents in fractional dimensional superconducting systems.Show less
We study the mathematics and physics involved in the generation of grav- itational waves by stellar mass binary black holes and their subsequent detection by LISA, a space based interferometer...Show moreWe study the mathematics and physics involved in the generation of grav- itational waves by stellar mass binary black holes and their subsequent detection by LISA, a space based interferometer detector. We show that LISA will be capable of detecting nearby binary black holes with a maxi- mal relative distance error of 0.2 and skylocation error of 1 square degree if the total mass of the binary is at least eighty solar masses.Show less
The results from Magnetic Resonance Force Microscopy measurements on electron spins in a diamond sample at milliKelvin temperatures are presented. A spin density on the surface of the diamond...Show moreThe results from Magnetic Resonance Force Microscopy measurements on electron spins in a diamond sample at milliKelvin temperatures are presented. A spin density on the surface of the diamond sample of (3.7 ± 0.2) · 10^6 µm^−2 was found by examining the resonance frequency of the cantilever as a function of the temperature of the sample. Also the energy in the motion of the cantilever was determined at different temperatures to conclude whether the cantilever was purely thermally excited. The results from these measurements are in contradiction with expectations, since the energy in the motion of the cantilever is smaller then expected at greater temperatures. The result could point to a temperature gradient in the setup. Furthermore, RF-pulses with different frequencies, durations and powers were sent, which made it possible to investigate the frequency shift in the resonance frequency of the cantilever as a function of the frequency of the pulse, the power of the pulse and the duration of the pulse. In addition, the relaxation of the spins in the sample, after sending an RF-pulse, was inspected with the result that the relaxation of the spins cannot be described by a single exponential function. This outcome could indicate an interaction between electron spins and nuclear spins.Show less
The goal of this thesis is to design a setup which can be used as a prototype for the TECH reactor. The TECH reactor is a cylinder with rounded edges, in which a microwave plasma will be formed....Show moreThe goal of this thesis is to design a setup which can be used as a prototype for the TECH reactor. The TECH reactor is a cylinder with rounded edges, in which a microwave plasma will be formed. The cavity should resonate with the right eigenmode at a constant frequency of 2.45 GHz, and the excitation structure should produce a reflection coefficient of smaller than 0.8, enabling a tuning device to maximize power transfer. These conditions must hold for a broad range of conductivities of the plasma. Firstly, the effect of a resonance frequency tuning ring inside the cavity was researched, in order to keep the right eigenmode at a constant frequency of 2.45 GHz. Secondly, the excitation structure was optimized to ensure that at the relevant plasma conductivities, the reflections from the setup were minimized. Later simulations yielded that for almost all conductivities of the plasma, the setup was sufficiently impedance matched to the waveguide to enable an auto tuning device to prevent reflections. Thirdly, unexpected eigenmodes of the cavity were discovered. Therefore, adjustments were made to the cavity such that the resonance frequencies of other modes would not be close to 2.45 GHz, to prevent the excitation of these modes. This thesis continued the work of De Man [3]. In the end, the simulations yielded promising results and the setup is almost fully designed. Soon, experiments with the electric field in the cavity can be carried out, which form an important step towards being able to measure plasma breakdown.Show less
T-cycle EPR is a novel technique developed for determining reaction rates and trapping reaction intermediates in the sub-second time domain [1]. In T-cycle EPR a sample containing two reactants is...Show moreT-cycle EPR is a novel technique developed for determining reaction rates and trapping reaction intermediates in the sub-second time domain [1]. In T-cycle EPR a sample containing two reactants is placed at low tempera- ture in a cryostat to halt the reaction. While in this cryostat the sample is then briefly heated with a laser. This will make the reaction proceed. After this heating pulse the sample is immediately cooled back to prevent it from reacting any further. In between each heating pulse, an electron paramagnetic resonance (EPR) spectrometer takes a spectrum. From these spectra the reaction can be followed and information about chemical rates and intermediates obtained. For T-cycle EPR to be possible one needs to know the temperature of the sample after heating, how fast the sample heats up to this temperature and possibly what temperature the sample reaches if the heating pulse is shorter than this heating time. This thesis focuses on answering these questions. For this a 275 GHz homebuilt EPR spectrometer was used. Here spectra were taken of a solution containing the nitroxide TEMPOL while heating at different heating laser powers. These spectra were then compared to spectra taken at known tempera- tures to find the sample temperature for each heating power. To find the heating time and the temperature reached for shorter heating pulses, the spectra were analyzed at one specific field position. This calibration has been done before by Panarelli [1] who got different results using the same setup. This shows the importance of repeating this calibration every time an experiment is performed as small changes in the hardware configura- tion may have an impact on the temperature calibration.Show less
KM3NeT is an international collaboration currently engaged in the development of a neutrino detector situated in the Mediterranean Sea. By investigating atmospheric neutrinos, its objective is to...Show moreKM3NeT is an international collaboration currently engaged in the development of a neutrino detector situated in the Mediterranean Sea. By investigating atmospheric neutrinos, its objective is to explore the fundamental characteristics of neutrinos, while also striving to study astro-particle physics by detecting high-energy neutrinos originating from celestial objects. Neutrinos interacting with seawater surrounding the detector create muons that emit Cherenkov radiation that can be detected. The reconstruction software employed aims to determine the energy and direction of these muons. This thesis briefly studies the underlying model, referred to as the PDF, shedding qualitative light on some of its internal mechanisms. The reconstruction software comprises a prefit stage and a fit of the PDF. In the second part of this thesis, the watershed algorithm is shown to be a promising alternative in the determination of the best distinct solutions of the prefit by effectively discerning symmetries among other considerations.Show less
This thesis discusses the development of a setup for measuring photocathode quantum efficiency (QE) in the preparation chamber of the Low Energy Electron Microscope setup (LEEM). The photocathodes...Show moreThis thesis discusses the development of a setup for measuring photocathode quantum efficiency (QE) in the preparation chamber of the Low Energy Electron Microscope setup (LEEM). The photocathodes are necessary for a new microscopy technique called Optical Near-field Electron Microscopy (ONEM). At the time of writing, a photocathode sample holder, and an anode have been created, along with the corresponding electrical connections and measurement software. To test whether the setup produced photoemission, two measurements were performed with an uncollimated 450 nm laser beam incident on a chromium photocathode that was cesiated with a Cs evaporator. The results show a current from anode to cesium evaporator, but no photoemission can be confirmed as the observed current fluctuations cannot be attributed to the laser beam with certainty.Show less
