The research collaboration KM3NeT is currently constructing neutrino telescopes at two sites in the Mediterranean Sea. The pointing accuracy of these two telescopes is of high importance to be able...Show moreThe research collaboration KM3NeT is currently constructing neutrino telescopes at two sites in the Mediterranean Sea. The pointing accuracy of these two telescopes is of high importance to be able to trace detected neutrinos back to their cosmic sources. Pointing can be cross checked with the cosmic ray shadow of the moon respectively the sun. In this research first the effects of mispointing of the KM3NeT/ORCA detector on the 2D map of the moon were evaluated. It is shown how various mispointing does in fact distort the 2D-map of a celestial object. Secondly the first six months of data with 4 lines of the KM3NeT/ORCA detector were used to investigate the cosmic ray shadow from both the sun and the moon. Extrapolated simulations for a year show that the statistics are currently not sufficient for a significant deficit of particles in the neighbourhood of the moon and the sun. In the analysis of the ORCA4 data the background of the moon and sun signal was evaluated using fake sources, following the path of the moon and with a given time delay. The background showed significant differences between different fake sources and also could be shown to behave differently for the moon and the sun. Further research is needed to investigate the discovered features and be able to recover the signal from the moon and sun shadowsShow less
KM3NeT is an international collaboration currently working on the construction of a neutrino detector in the Mediterranean Sea. During the period evaluated in this research, two detection strings...Show moreKM3NeT is an international collaboration currently working on the construction of a neutrino detector in the Mediterranean Sea. During the period evaluated in this research, two detection strings were deployed and active. With this new detector, the KM3NeT collaboration aims to discover the neutrino mass ordering and scan for cosmic neutrino sources. In order to accurately reconstruct neutrino interactions, the detector elements must be synchronized within nanoseconds. The goal of this research is to evaluate whether the signal of passing atmospheric muons can contribute in the time calibration. The data was scrutinized for detector malfunctions and cleaned. The detector performance was then checked by using signal coincidences between detector elements to evaluate correlated signals, stemming from atmospheric muons. This allowed also to determine the dependence of the muon rate on the depth and assess potential time o sets. A time offset of 30 ns between the two operating detector strings was found, which will require further investigations.Show less
Since the arrival of millimeter wave interferometers and their subsequent advancement, the resolution of observations has improved significantly. However, the effects of these improvements have not...Show moreSince the arrival of millimeter wave interferometers and their subsequent advancement, the resolution of observations has improved significantly. However, the effects of these improvements have not yet been investigated. This research examines the effect of improving resolutions to SubMillimeter Galaxies (SMGs) like simulated Gaussian sources. To achieve this, simulated 350 GHz ALMA observations with 20 different antenna configurations with resolutions ranging from 0.05 to 1.1 arcsec of simulated Gaussian sources performed with CASA are used. For resolutions better than 0.2 arcsec, depending on the SNR, the flux and size from observations obtained with an image plane analysis, where the size is found using CASA, can be significantly lower than the true flux and size, due to the largest angular scale of the observations. Fitting a circular Gaussian to the uv-plane data demonstrates that the $uv$-plane analysis more accurately recovers the true FWHM than the image plane analysis using CASA. However, the major and minor axes of an elliptical source are not recovered and the size of an elliptical source is overestimated with the uv-plane analysis. Different SMG companion fields from the ALESS and UDS survey originally observed by Hodge et al. (2013), Simpson et al. (2015) and Wardlow et al. (2018) and quasar fields with a companion detected by Decarli et al. (2017) were simulated with circular Gaussian sources to examine the influence of companion sources to the FWHM of the main source acquired with the $uv$-plane analysis. Generally, the companions in the companion fields examined do not show an influence on the FWHM of the main source.Show less
The KM3NeT Neutrino telescope is a telescope in the Mediterranean sea researching neutrino events to study both neutrino properties and neutrino sources in the universe. While searching for...Show moreThe KM3NeT Neutrino telescope is a telescope in the Mediterranean sea researching neutrino events to study both neutrino properties and neutrino sources in the universe. While searching for neutrinos, the detector observes noise from bioluminescence and 40K decay as well. The 40K noise is constant and homogeneous, and the bioluminescence consists of high peaks in the signal (bursts) and is periodic in nature. In this research the periodicity of the bioluminescence was researched for the different detectors, together with the general noise characteristics of the detectors and their effect on the muon track reconstruction. The periodicity was found to be consistent with the current around the detectors and the inertial waves caused by the Coriolis force, though there is slight variation in the frequency. The bioluminescence can cause slightly less muon events to be reconstructed, though track distributions are similar to those with less bioluminescent noise.Show less
KM3NeT is a research collaboration currently building a neutrino telescope in the Mediterranean Sea. The aim of KM3NeT is to discover the source of astrophysical neutrinos and to uncover the true...Show moreKM3NeT is a research collaboration currently building a neutrino telescope in the Mediterranean Sea. The aim of KM3NeT is to discover the source of astrophysical neutrinos and to uncover the true neutrino mass hierarchy. In order to achieve its scientific goals, KM3NeT requires 1-2 ns time calibration accuracy. Preliminary time calibration is currently executed using a laser setup. This research explores the use of background signals from air showers instead. The air shower method is shown to be robust and consistent within 0.5 ns. Furthermore, this time calibration corresponds to laser calibrations within 1 ns. Thus, the air shower time calibration provides a cross check for current methods and it could be used as a cheaper and easier method for future time calibration facilities. Secondly, the decay of atmospheric muon signals in the sea is investigated as a detector performance cross check. The muon depth dependence is very stable after all corrections and considerations discussed in this research. Any large deviations from the expected muon signal may be used as an indicator for lower efficiency in the detector. Furthermore, comparisons between detectors can show consistency in the time calibrations. Overall, background signals of atmospheric origin, though not being the objective for KM3NeT, are shown to provide valuable detector cross checks.Show less
This research paper presents the investigations on the impact of Earth’s magnetic field on the efficiency of 3-inch photomultiplier tubes used in the KM3NeT neutrino telescope. The research...Show moreThis research paper presents the investigations on the impact of Earth’s magnetic field on the efficiency of 3-inch photomultiplier tubes used in the KM3NeT neutrino telescope. The research includes measurements of three Hamamatsu PMTs. The measurements show that the efficiency of the PMTs are directional-dependent. However, this significance is most probably not caused by Earth’s magnetic field only. Further investigation is needed to determine where these external effects come from.Show less
Currently still under construction, the KM3NeT neutrino telescope in the Mediterranean Sea will be used to detect atmospheric and cosmic neutrinos. KM3NeT will consist of large cubic arrays of...Show moreCurrently still under construction, the KM3NeT neutrino telescope in the Mediterranean Sea will be used to detect atmospheric and cosmic neutrinos. KM3NeT will consist of large cubic arrays of large amounts of optical sensors. The detector will exploit Cherenkov radiation emitted by energetic secondary particles. To have an understanding of the performance of the detector, knowing about the performance of the different digital optical modules (DOMs) is vital. Using various methods (mainly potassium decay, 40K -> 40Ca), relative sensitivities of the different DOMs have been measured. However, only rough estimates for absolute efficiencies are known. A novel method will be developed to cross check the results previously found. This research will exploit atmospheric muons and probe the sensitivity of the KM3NeT neutrino telescope. Events in which multiple DOMs in a row detect a muon are used. Both threefold and fourfold combinations are used. Ratios are introduced to describe the fraction of times all DOMs are hit over the outer DOMs. This scales with efficiency. Simulations are used to describe extinction and propagation of Cherenkov photons and muons in water.Show less
This thesis studies the origin of large signals detected in the KM3NeT optical modules. The origin of the signals is directly studied with the single PMT and indirectly with the DOM. The results of...Show moreThis thesis studies the origin of large signals detected in the KM3NeT optical modules. The origin of the signals is directly studied with the single PMT and indirectly with the DOM. The results of both the single PMT and the DOM point toward a high energetic particle origin. Further measurements are required to conclude this with certainty.Show less
The KM3NeT-neutrino telescope is a large detector under construction in the Mediterranean Sea. Its main objectives are the observation of cosmic high-energy neutrinos and the determination of the...Show moreThe KM3NeT-neutrino telescope is a large detector under construction in the Mediterranean Sea. Its main objectives are the observation of cosmic high-energy neutrinos and the determination of the neutrino mass hierarchy. However, the deep sea is an extraordinary location and environment and entails uncontrolled phenomena like bioluminescence. Bioluminescence is the emission of light by organisms. This light is detected by the KM3NeT-detector when bioluminescent organisms collide with the structure of KM3NeT. It is interesting to study the signal of the bioluminescence, because it tells a lot about life in deep-sea and it can be a nuisance in the quest to observe and research neutrinos. Characteristics of bioluminescence like the amount of detected bioluminescence over a long period of time, the location of the increased bioluminescence in the detector, the number of bioluminescent bursts that happen at the same time, the duration of these bursts and the periodicity of the detected bioluminescence are investigated. Finally in the analysis of the data it has been found that some parts of the detector are showing unexpected behaviour, examples of this behaviour are shown.Show less
The KM3NeT detector is a neutrino telescope under construction in the Mediterranean Sea. High-energy particles travelling at great velocities can emit underwater light, which is measured by the...Show moreThe KM3NeT detector is a neutrino telescope under construction in the Mediterranean Sea. High-energy particles travelling at great velocities can emit underwater light, which is measured by the detector. Data coming from the parts that are already deployed can be interpreted and analysed to determine characteristics of these incident particles. Muons are of particular interest in this research, because they can be easily identified as such. Nearly all muons approach the detector from above and, as it spans well over 600 m in length, muons are measured at different depths. Because of the large volume of sea water between the highest and the lowest part of the detector, it is expected that more muons are measured at the top than at the bottom. In a few separate ways it has been shown that this is indeed the case. Fewer hits are measured deeper down the detector, which means that the muon hit rate is dependent of the depth. It has been demonstrated that the distance over which the muon intensity halves is equal to 530 m. Comparing the data with Monte Carlo simulations has shown good agreement.Show less
The purpose of this research is to investigate the performace of a prototype detector for a neutrino telescope built in the Mediterranean Sea. The telescope consists of photomultiplier tubes which...Show moreThe purpose of this research is to investigate the performace of a prototype detector for a neutrino telescope built in the Mediterranean Sea. The telescope consists of photomultiplier tubes which record the position and time stamps of Cherenkov light created by charged particles form e.g. neutrino interactions. This investigation is done to find neutrino sources in the cosmos which could lead to a better understanding of active galactic nuclei, supernova remnants, micro-quasars and gammaray bursts. We used the data of a prototype where most of the signals stem from muons created in atmospheric interactions of cosmic rays. In the first part the properties of the detected signals are being investigated and we look for a lower limit to have a noise free signal when looking for Cherenkov light created by charged particles between multiple digital optical modules. The last part of this project is devoted to calibrating the observed data with the simulated data so that in future experiments it could be seen at which time a particle is detected with nanosecond precision and thus with an angular precision of a tenth of a degree the direction and path of particles could be constructed.Show less
