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
Superconducting nanostructures can be used to detect single photons. Here we propose to use electron-beam-induced deposition (EBID) of a superconducting tungsten-carbon alloy to create nanowires...Show moreSuperconducting nanostructures can be used to detect single photons. Here we propose to use electron-beam-induced deposition (EBID) of a superconducting tungsten-carbon alloy to create nanowires that can be used as a transition edge sensor (TES). Determining if these EBID-written nanowires can be used as an efficient TES requires an experimental characterization of its electrothermal properties. We demonstrate two key experiments to characterize a TES and introduce a numerical model to describe a TES with a nanofabricated constriction as a proof-of-concept. We characterize the low frequency impedance of a PTC thermistor and determine its electrothermal properties. We find a thermal conductance $G = 5.1 \pm 0.2 \text{ \textmu W/K}$ and a heat capacity $C = 0.48 \pm 0.03 \text{ \textmu J/K}$ and discuss how to extend these measurements to superconducting nanowires. A remotely controlled experiment is performed on NbTiN nanowires with a nanofabricated constriction. From the measured IV curves we determine the Joule heating and local temperature of the wire from an adapted Skocpol-Beasley-Tinkham model for a resistive transition. This model is valid for low values of the wire resistance. Together, these experiments and the model provide necessary infrastructure to characterize the electrothermal properties of EBID-written nanowires in the near future.Show less
Quantum computers can possibly help in the near future to simulate mole-cules and do electronic structure calculations. To work on the near term quantum devices the variational quantum eigensolver ...Show moreQuantum computers can possibly help in the near future to simulate mole-cules and do electronic structure calculations. To work on the near term quantum devices the variational quantum eigensolver (VQE) is an auspicious candidate and particularly the application of the unitary coupled-cluster singles and doubles ansatz. Despite the high accuracy the scaling in the number of terms is unfavourable making the circuit depth too large. In this thesis we look at a possible truncation scheme based on classical quantum chemistry methods to decrease the number of terms while preserving accurate ground state energies. This truncation is shown with numerical results for H$_4$ and N$_2$ giving a significantly reduced number of terms.Show less
To find solutions to systems of conservation laws with discontinuities, weak solutions will be studied. To pick a unique weak solution one requires some additional conditions. In this thesis we...Show moreTo find solutions to systems of conservation laws with discontinuities, weak solutions will be studied. To pick a unique weak solution one requires some additional conditions. In this thesis we will see that for the Riemann problem in one spatial dimension, the Lax entropy conditions are a way to do this. By considering the Euler equations we will see that these conditions are equivalent to the second law of thermodynamics and therefore pick the physically relevant solution. Furthermore, we construct numerical solutions to a specific Riemann problem using a standard discretization method and a method based on nonlinear shocks, followed by a on discussion their strengths and weaknesses.Show less
Nucleosomes condense DNA into higher order chromatin structures and the position of nucleosomes play an important role in the regulating of transcription. Current methods can only map ensemble...Show moreNucleosomes condense DNA into higher order chromatin structures and the position of nucleosomes play an important role in the regulating of transcription. Current methods can only map ensemble averaged nucleosome profiles. Here we make use of the property that nucleosomes protect the DNA against methylation, induced by methyltransferase enzymes. Nanopore sequencing is subsequently used to detect methylated bases on single DNA molecules. This makes a single molecule approach possible for detecting nucleosomes. We use the Nucleosome-Unmethylated-Score(NUS) to map nucleosomes on single DNA molecules. The NUS was tested by mapping nucleosome occupancy on high nucleosome affinity 601 arrays. The NUS was further used to analyse active and silent genes in Saccharomyces cerevisiae rDNA and to characterise nucleosome remodelling in reconstituted chromatin by whole cell extract (WCE) proteins.The found nucleosome occupancy was comparable with in vivo positions observed from ensemble averaged data. Nucleosome detection on single molecules advances our understanding of chromatin structure and its role in transcription regulation.Show less
Dielectrophoresis is a widely used technique for on-chip manipulation of polarizable objects like cells, viruses and microparticles. Recently the use of nanotechnology enabled scaling down the...Show moreDielectrophoresis is a widely used technique for on-chip manipulation of polarizable objects like cells, viruses and microparticles. Recently the use of nanotechnology enabled scaling down the dielectrophoretic trapping to the level of nanoparticles and even single molecules. We aim to develop a dielectrophoresis-based tool to trap and actuate single biomolecules in order to study them. In this thesis we have designed and simulated a nanoscale dielectrophoretic trap as well as explored the possibilities of actuating trapped nanoparticles between the two hotspots of the trap. The simulation framework developed in this thesis based on COMSOL Multiphysics and python simulations paves the way to smart engineering of single-molecule dielectrophoretic traps, which can reduce the cost and time for production and development.Show less
Visual and spectroscopic observations were done on laser induced toroidal helium plasmas to determine its geometric properties as well as get an estimate of the temperature. These measurements were...Show moreVisual and spectroscopic observations were done on laser induced toroidal helium plasmas to determine its geometric properties as well as get an estimate of the temperature. These measurements were combined in an effort to gain insight into its underlying thermodynamic processes. At 10μs after creation, the torus was found to have a temperature in the order of 2500K, decreasing to 1000K at 50μs. During this period the volume of the torus increased by a factor in the order of 2.5. It was investigated whether this drop in temperature and increase in volume would follow a model of adiabatic expansion. A least squares fit gave a value of the adiabatic constant of γ = 1.21. More observations must be done to increase the accuracy of these values in order to make substantive conclusions.Show less
A catalogue of a total of 171 galaxies, supplemented with their redshift, is created for three deep, blank fields observed by MUSE. Furthermore, a study of the physical properties of 65 low-mass...Show moreA catalogue of a total of 171 galaxies, supplemented with their redshift, is created for three deep, blank fields observed by MUSE. Furthermore, a study of the physical properties of 65 low-mass galaxies is performed for these fields. A model for the process of star formation in galaxies is discussed, and its parameters are constrained by observed data in the MUSE fields. Here, a relation between star formation rate (SFR) and stellar mass (M_*) of SFR / M_* ~ M_*^a with a = 0.72 +0.11-0.13 is found, with a redshift evolution of SFR / (1 + z) ~ b with b = 5.58 +3.0-2.8. The relation has an intrinsic scatter of s_intr = 0.61 +0.15-0.13. Lastly, the calibration techniques of the MUSE instrument are investigated, showing that the instrument is quite sensible to temperature changes.Show less
