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Transcript

Physics Annual Symposium 2015/16 B.Sc. (Hons) Physics Project Date: Time: Venue: Wednesday, 4th May 2016 8.30 – 17.00 MP216 8.30 – 8.45 Introduction & Objectives of the Symposium Head of Department: Professor CV Sammut 8.45 – 9.00 Student: Gabriel Falzon Title: An Integrated system for Telescope Control using FPGAs Chairman: Prof C V Sammut Supervisor: Prof K Zarb Adami Examiner: Dr A Magro 9.00 – 9.15 Student: Kevin Psaila Title: f(R,T) Reconstruction Models in FLRW Cosmologies Chairman: Prof C V Sammut Supervisor: Dr J Said Examiner: Prof K Zarb Adami 9.15 – 9.30 Student: Andrew Finch Title: Gravitomagnetic Effects in Quadratic Gravity Chairman: Prof C V Sammut Supervisor: Dr J Said Examiner: Prof K Zarb Adami 9.30 – 9.45 Student: Daphne Pollacco Title: Measurement of Complex Permittivity of Sodium Chloride and Tissue mimicking Solutions from 100MHz to 3GHz. Chairman: Prof K Zarb Adami Supervisor: Prof C V Sammut/Dr L Farrugia(co-supervisor) Examiner: Dr L Zammit Mangion 9.45 – 10.00 Student: Jacob Spiteri Title: Electrodynamic Levitation Chairman: Prof C V Sammut Supervisor: Dr L Zammit Mangion Examiner: Dr A Xuereb 10.00 – 10.15 BREAK 1 10.15 - 10.30 Student: Melissa Caruana Title: Entropy and Correlations in an Open Quantum System Chairman: Prof C V Sammut Supervisor: Dr A Xuereb Examiner: Prof A Micallef 10.30 - 10.45 Student: Antonella Cutajar Title: Development and Evaluation of a Simple Dispersion Model for an Atmospheric Point Source Chairman: Prof R Ellul Supervisor: Prof A Micallef Examiner: Dr P S Farrugia 10.45 – 11.00 Student: Nicolai Cumbo Title: Investigating the Expansion of a Braided Interplanetary Magnetic Field Chairman: Prof C V Sammut Supervisor: Dr P S Farrugia Examiner: Prof A Micallef 11.00 – 11.15 Student: Massimo Grech Title: Dating a Large Tsunami Event on the Maltese Islands Chairman: Dr G Debono Supervisor: Dr A Micallef Examiner: Dr P Galea M.Sc. Project 11.15 -11.45 Student: Mark Pace Title: Extreme Stars in Modified Gravity Chairman: Professor CV Sammut Examiner: Dr J Said Examiner: Prof K Zarb Adami 2 B.Sc. (Hons) Short Review Paper and Seminar 14.00 - 14.15 Student: Massimo Grech Title: Underwater landscapes of the central Mediterrenean Sea Chairman: Dr P Galea Supervisor: Dr A Micallef Examiner: Prof A Drago 14.15 - 14.30 Student: Nicolai Cumbo Title: The Inner Workings of Neutron Stars Chairman: Prof C V Sammut Supervisor: Dr J Said Examiner: Prof K Zarb Adami 14.30 - 14.45 Student: Andrew Finch Title: The Cosmic Microwave Background Radiation: Source and Anisotropy Chairman: Professor C V Sammut Supervisor: Dr J Said Examiner: Prof K Zarb Adami 14.45 – 15.00 Student: Kevin Psaila Title: Dark Energy Chairman: Prof C V Sammut Supervisor: Dr J Said Examiner: Prof K Zarb Adami 15.00 – 15.15 Student: Jacob Spiteri Title: Casimir-Polder Force and Casimir Friction Chairman: Prof C V Sammut Supervisor: Dr A Xuereb Examiner: Dr P S Farrugia 15.15 - 15.30 Student: Gabriel Falzon Title: Origins of “the Quantum Advantage” Chairman: Prof C V Sammut Supervisor: Dr A Xuereb Examiner: Dr P S Farrugia 15.30 – 15.45 BREAK 15.45 – 16.00 Student: Melissa Caruana Title: Observable Consequences of Quantum Statistics: from Cooper Pairs to Bell Chairman: Prof C V Sammut Supervisor: Dr A Xuereb Examiner: Prof A Micallef 16.00 – 16.15 Student: Daphne A Pollacco Title: Microwave Medical Imaging 3 Chairman: Prof A Micallef Supervisor: Professor C V Sammut Examiner: Dr L Zammit Mangion 16.15 – 16.30 Student: Antonella Cutajar Title: The Physics of Urban Climatology Chairman: Prof R Ellul Supervisor: Professor A Micallef Examiner: Dr P S Farrugia 16.30 – 16.45 Student: Anita Farrugia Title: The Role of Hydrocarbons and other Volatile Organic Compounds in the Earth’s Atmosphere Chairman: Dr P S Farrugia Supervisor: Prof R Ellul Examiner: Dr A Galea Closing 4 Abstracts B.Sc. (Hons) Physics Project Student: Gabriel Falzon Title: An Integrated System for Telescope Control using FPGA(s) Abstract: Astronomical radio interferometers typically consist of an array of antennas, widely separated and connected using a transmission line. Signals recorded from each antenna are sent to a back-end where they are digitized, channelized and superposed, giving rise to constructive / destructive interference depending on whether the signals are phased or not. This technique of interferometry is called aperture synthesis and it results in a combined telescope, with a resolution equivalent to that of a single antenna with a diameter equal to the spacing of the antennas furthest apart in the array. When we consider a radio signal from a celestial source, incident on two antennas separated by a distance, the antennas receive the radio signal with a time difference, causing the signals to be out of phase. In order to achieve amplitude amplification, the recorded signals must be phased using a technique called beamforming. A beamformer, has the added capability of steering the beam of a radio telescope using constructive / destructive interference. The aim of this project is to design and implement an integrated control system (ICS) for the digital steering of beams in a radio telescope. The system will be implemented on the ROACH2 FPGA board and will be capable of continually steering beams in the sky, whilst monitoring the behavior of a phased array system to ensure that the beams are continually tracking a source. Student: Kevin Psaila Title: f(R,T) Reconstruction Models in FLRW Cosmologies Abstract: The concept of gravity is very important yet there is no complete description on how this force actually works. It can be a manifestation of curvature in the geometry of spacetime, as postulated by Einstein, or something else. Although the General Relativity viewpoint turned out to be the most successful theory in describing gravity, it is still an incomplete theory of gravity since it fails at explaining certain phenomena that are currently being observed such as galactic rotation curves and the accelerated expansion of the Universe in recent times. As a result cosmologists are trying 5 to find alternative theories of gravity that are consistent with the current observations. f(R,T) modified theories of gravity will be investigate and by assuming that the expansion history of the universe is known, field equations are inverted to get to determine which modified theory gives a flat Friedmann−Robertson−Walker model. Modified f(T) (where T is the trace of the energy-momentum tensor) models of gravity will also be reviewed in order to obtain a new solution for the scale factor, Hubble parameter and deceleration parameter in terms of the cosmic time. A completely new toy model, that describes the cosmic evolution from 13.7 billion years ago till the present time, will be proposed which is found to be consistent with dark energy; something that the original theory of general relativity does not predict. This toy model is further extended to examine the scale factor behavior in the nearby and distant future so that the fate of the universe can be determined. Student: Andrew Finch Title: Gravitomagnetic Effects in Quadric Gravity Abstract: In this presentation the concept of alternate theories of gravity will be briefly discussed leading to the one used throughout my thesis, that of quadric gravity. A Kerrlike metric in quadric gravity for the vacuum space outside of a rotating, spherically symmetric gravitational source will then be considered. The equations for Kepler’s third law and two gravitomagnetic effects, the geodetic precession effect and the Lens Thirring effect in quadric gravity will then be presented and compared to their general relativistic counterparts. Finally results obtained from these equations when applied to a specific system, that of a satellite orbiting the earth, will be presented and interpreted. Student: Daphne A Pollacco Title: Measurement of Complex Permittivity of Sodium Chloride and Tissue mimicking Solutions from 100MHz to 3GHz. Abstract: The aim of this work was to investigate the dielectric properties of solutions which can be used to mimic the electrical properties of human breast tissues. By analyzing the dielectric properties of tissue mimicking solutions, it is possible to characterise the interaction of electromagnetic fields with the human body, the amount of energy that the body absorbs and how much ionic currents are induced in the body. Previous studies have used sodium chloride (NaCl) and Triton X-100 to approximate the dispersive dielectric properties of a variety of human soft tissues from 500 MHz up to 6GHz. Different tissues can be mimicked by a selection of the appropriate concentration of NaCl and Triton X-100 solutions. In this study, measurements were conducted on 21% TX-100, 28% TX-100 and 40% TX-100 in order to mimic different percentages of adipose in breast tissues while extending current knowledge to 100MHz. Measurements were performed at 25 and 37 degrees Celsius. Prior to conducting these measurements, a new, state-of-the-art probe (DAK) was validated by conducting measurements on 0.1 N NaCl. The results were analysed and compared to those published in the literature and then fitted to relaxation models. Most dielectric 6 parameters were observed as a function of frequency and temperature. Measurement uncertainty analysis was also performed for both saline and Triton X-100 solutions. These results contribute to further research in microwave diagnostic and therapeutic applications in medical physics for safer and more reliable detection of breast cancer as well as application in microwave hyperthermia. Student: Jacob Spiteri Title: Electrodynamic Levitation Abstract: Magnetic levitation has been a topic of interest since the 19th century electromagnetism boom, and still is today. There are many ways to achieve a controllable lift using various electromagnetic methods. Up to a a couple of years ago the idea of having a floating rideable personal 'hoverboard' was a Sci-Fi dream, immortalized by the 1989 movie 'Back to the Future Part II'. In November of 2014 a company from California, U.S.A introduced a rideable floating 'Hoverboard' using maglev technology as a 'Kickstarter' project. Following an overview of various magnetic levitation technologies, this work focuses solely on electrodynamic levitation. Computer simulations and experimental measurements were performed for two methods, using ac induction from a coil and using a system of rotating permanent magnets similar to that used in the Hoverboard. Student: Melissa Caruana Title: Entropy and Correlations in an Open Quantum System Abstract: An open quantum system, as the name suggests, is a quantum-mechanical system which interacts with the rest of the universe. We will start by looking at Landauer's principle and its relation with the second law of thermodynamics and with information. This thesis will then look at the correlations, heat exchanged and entropy of a simple open quantum system that interacts with its environment as we tune this interaction from a simple Markovian one, which is an interaction that does not maintain a memory of the past to one that is increasingly non Markovian. Student: Antonella Cutajar Title: Development and Evaluation of a Simple Dispersion Model for an Atmospheric Point Source Abstract: Atmospheric dispersion modelling is an essential tool for studying the effects of air pollution and is very frequently used to set regulations for the introduction of new sources of pollution in the environment. In this project, a simple Gaussian dispersion model is developed to study the dispersion of a plume from a stack. Three versions of the model are created; in each one a different formulation is used to calculate the horizontal and vertical dispersion coefficients. The model is then evaluated using the Thompson wind tunnel data – a data set collected from experiments carried out in the U.S. Environmental Protection Agency wind tunnel. Validation is made through linear regression and statistical analysis. Results show that the model slightly underestimates pollutant concentration as the plume is modelled to disperse much quicker than it does in reality; however there is a fair linear correlation between the observed data and the 7 predicted values. A relation between height of stack and model performance is also observed. Finally, some modifications to the horizontal dispersion parameters are implemented using curve fitting techniques. Such modifications indeed show an improvement in the results output by the model. Student: Nicolai Cumbo Title: Investigating the Expansion of a Braided Interplanetary Magnetic Field. Abstract: Plasma motion in the Sun creates a persistent magnetic field that extends outwardly as far as Pluto and beyond. Assuming a steady state system, this so called interplanetary magnetic field takes the shape of an Archimedes spiral, known as the Parker spiral. However, the outer layers of the Sun are evolving continuously creating fluctuations in the magnetic field lines. These braid the magnetic field lines making its representation much more complicated. As the magnetic field lines move outwardly from the Sun, the separation between them increases. This affects the transport properties of fast moving particles, called solar energetic particles, which are emitted from the sun. Such particles are of interest not only because they are a health hazard in outer space, but also because they can be used to probe the magnetic turbulence of outer space. Thus, it is important to account for the expansion of the magnetic field lines when calculating their transport properties. While an analytical model for the expansion of the Parker spiral in terms of area enclosing a fixed amount of flux is readily derived, that for a braided magnetic field could not be obtained so easily. In this context, the research uses numerical techniques in order to investigate the evolution of a braided field line. It then builds on the result to determine how the area enclosing a fixed amount of flux in such a field changes with radial distance from the Sun. Student: Massimo Grech Title: Dating a Large Tsunami Event on the Maltese Islands Abstract: The Maltese Islands have been subject to numerous tsunamis in the past, some of which were strong enough to modify the shape of our coastlines. Various historians describe an earthquake in 1693, which resulted in a tsunami that affected Xlendi, where the sea “rolled out to 1 mile and swept back a little later”. Another tsunami was triggered by the 1908 Messina earthquake, although this had limited impact on the Maltese archipelago, such as localised flooding and minor strucural damage. On the north-eastern coasts of Malta several erosional forms including 70-ton boulders and 11 m by 6 m large socket forms can be found. A recent study by Mottershead et al. (2014) investigated geomorphic signatures at Ahrax and other coastal sites to propose that a 20 m tsunami wave affected the eastern coastline of the Maltese Islands. The objective of this 8 dissertation is to test the validity of this hypothesis by analysing the nature and distribution of sediments along the Ahrax coast and explain the latter using hydrodynamic equations. An attempt is also made to estimate the age of the tsunami event. M.Sc. Project Student: Mark Pace Title: Extreme Stars in Modified Gravity Abstract: Neutron stars represent the extreme regime where gravitational and particle physics meet. They suffer the intense inward pressure of gravity and, at the same time, a large outer pressure due to the interactions of the particles pressure. These 10 km radius stars are under such intense pressures that all the atoms present have broken down into their constituent components. Computer simulations will be used to compute the differences that competing theories of gravity produce in terms of this strong end of the region. Up to this point in time such research has mostly been done using Einstein’s theory of gravity, general relativity, however a growing number of researchers are starting to use this as a test of modification to this model in order to better explain some of its shortcomings. Theories based upon the curvature scalar have been extensively studied, however new up and coming theories have been emerging where instead of the curvature scalar, we base our theories on the torsion of the space-time through the Weitzenbock connection, called f(T). Such a theory however does not take into account the aspect where the cosmological constant may be a variable, which may depend on the trace of the energy-momentum tensor, T . Thus giving rise to the f(T, T ) theory of gravity. f(T, T ) theory of gravity is a more general form of f(T) theory. This project’s goal is to apply such a theory to extreme stars, and attempt to derive the governing equation; Tolman Oppenheimer Volkoff (TOV) equation. Having such an equation then allows us to study the mass-radius relation of the neutron star within a certain strong field gravity. 1 B.Sc. (Hons) Short Review Paper Student: Massimo Grech Title: Underwater landscapes of the central Mediterranean Sea Abstract: Although the surface layers of the Mediterranean are generally well known to many, some of its deeper layers remain a mystery. This is mainly due to the difficulties encountered in order to investigate at these depths, which can be predominantly done using geophysical instruments. The objective of this study is to shed light on the underwater landscapes of the central Mediterranean and what we know about them up till 9 now. These include the Malta-Sicily Escarpment (MSE), the Ionian Abyssal Plain (IAP), the Malta Plateau, the Malta Graben, and the Gela Basin. A discussion of the submerged terrestrial landscapes of the Maltese Islands is also given. With sea levels rising, the general interest in underwater landscapes and their exploration is also expected to increase in the future. Student: Nicolai Cumbo Title: The Inner Workings of Neutron Stars. Abstract: The state of the matter at the core of Neutron Stars remains uncertain to this day. However, models based on theoretical possibilities have been formed, and compared to observational data where possible. These models depend highly on the equation of state (EOS), which is a relation between the pressure of the matter present and the density. In this presentation, the EOS of the outer core of Neutron Stars is reviewed, followed by the simplest form for the inner core. Next, several 'exotic' phases of matter are reviewed, and their effect on the EOS explained. Student: Andrew Finch Title: The Cosmic Microwave Background Radiation: Source and Anisotropy Abstract: In this presentation the origin and the mapping of the cosmic microwave background radiation (CMB) and its anisotropies will be considered including an overview of the three space missions dedicated to this task. Finally the significance of the CMB and its anisotropies along with their contribution to modern cosmology will be outlined. Student: Kevin Psaila Title: Dark Energy Abstract: Relatively recent observations have confirmed that around 70% of the Universe is made up of dark energy which is the key component for the current cosmic accelerated expansion. In this paper, present observational evidence and theoretical models that have been proposed in trying to explain dark energy and its negative pressure under the important assumption of a flat Universe are reviewed. Various probes of dark energy including baryon acoustic oscillations, Supernovae type Ia and weak gravitational lensing will be discussed. The two leading theoretical models, the cosmological constant model and the quintessence model, will also be reviewed together with the fine tuning and coincidence problems. The "tracking" solution will also be introduced as an explanation for the fact that the energy densities of matter and vacuum energy are of the same order at approximately the present time. Student: Jacob Spiteri 10 Title: Casimir-Polder Force and Casimir Friction Abstract: 69 years ago in 1947, two Dutch physicists named Hendrik Casimir and Dirk Polder theorized the existence of an attractive force between two neutral atoms, and between an atom and a conducting plate, this is known as the Casimir-Polder force. A year later Casimir formulated the force between two neutral conducting plates in a vacuum, this is generally known as the Casimir Effect. Since then the notion of quantum/Casimir friction has come up, this phenomenon entails this Casimir-Polder type force on a moving atom causing a dissipative quantum electrodynamic force, i.e. a friction like force. Theorists have tried to describe and quantify this force for more than 3 decades now. This review gives an overview of what has been done up to now with regards to theory and experimental work on this minute force. Student: Gabriel Falzon Title: Origins of “the Quantum Advantage” Abstract: Quantum information theory predicts that certain algorithms undergo speedup when implemented on quantum machines, making them more efficient than classical implementations. This review presents a qualitative description of this increased efficiency, termed `quantum advantage', by defining computational complexity and investigating Shor's and Grover's quantum algorithms. Among the proposed sources of this quantum advantage is the non-local correlation known as entanglement. This review, explores how entanglement is an essential resource for pure-state quantum algorithms but not a necessity for quantum algorithms operating on mixed-states. Efficiencies achieved by mixed-state quantum computations force the introduction of a concept known as discord and an investigation of how it came to be considered a resource for the mixedstate DQC1 model. A discussion on the role of entanglement and discord, as resources for the quantum advantage in quantum computation and communication, presents significant arguments to the open question about the origin of the quantum advantage. Student: Melissa Caruana Title: Observable Consequences of Quantum Statistics: From Cooper Pairs to Bell Abstract: The elementary particles that make up ordinary matter are bosons and fermions which obey different statistics. There are other particles such as anyons which are neither bosons nor fermions, but somewhere in between and obey another type of statistics. In what follows, we will give a brief description of bosons and fermions and go into detail about anyons, their statistics and the phenomena they lead to. The difference between classical and quantum statistics will then be discussed using Heisenberg's Uncertainty Principle and arguments from the famous EPR paper and Bell's Theorem. 11 Student: Daphne A Pollacco Title: Microwave Medical Imaging Abstract: This paper reviews microwave imaging techniques used in the screening for and diagnosis of tumours, with special reference to breast cancer. There are various microwave imaging techniques which can be used to diagnose cancer and these can be classified into three modalities. These are: hybrid microwave induced acoustic imaging techniques, ultra-wide band radar based imaging and microwave tomography. Out of these three modalities, the ultra-wide band microwave (UWB) imaging technique is a particularly popular, emerging new field of research. Currently, mammography is the most prevalent screening method in most medical institutions. However it has its disadvantages. Ituses ionising radiation, it is highly uncomfortable because it involves compression of the breast while offering low resolution images. The UWB technique, on the other hand, utilizes non-ionizing radiation and eliminates the discomfort of breast compression. However, the sensitivity and the possibility of differentiating between benign and malignant tumours is still highly debatable in this field of research. This paper reviews past, current and future potential use of microwave imaging methods, the fundamental principles in physics dominating this new field of research and the mathematical analysis that goes along with interpreting the results obtained through microwave imaging. Research in microwave medical imaging is still being carried out till this day and it is still debatable whether this technique will take over current imaging modalities. Student: Antonella Cutajar Title: The Physics of Urban Climatology Abstract: With the rapid increase in the number of urban dwellers, the study of urban climatology has become increasingly important over the last few decades. The development of urban settlements and the activities cities bring with them lead to the creation of microclimates. The main parameters that are modified in these newly created microclimates include: the atmospheric composition, the heat budget, wind speed and humidity. In this review paper, the processes by which these modifications arise are studied and the effects of such modified microclimates are also outlined. Some precautions that should be taken while developing cities to help minimise the culprits of urbanisation are also mentioned. Student: Anita P Farrugia 12 Title: The role of Hydrocarbons and other Volatile organic compounds in the Earth’s atmosphere Abstract: Hydrocarbons and other volatile organic compounds (VOCs) are abundant in sources and a cause of several detrimental health and environmental effects. Their presence in both indoor and outdoor environments is a result of both anthropogenic and biogenic activity, this means that they are near impossible to escape, with concentrations varying depending on population sizes, urban and industrial activity. This review aims to discuss the sources of these VOCs present in the atmosphere as well as their resulting effects on both human health and the environment. Student: Massimo Grech Title: Underwater landscapes of the central Mediterranean Sea Abstract: Although the surface layers of the Mediterranean are generally well known to many, some of its deeper layers remain a mystery. This is mainly due to the difficulties encountered in order to investigate at these depths, which can be predominantly done using geophysical instruments. The objective of this study is to shed light on the underwater landscapes of the central Mediterranean and what we know about them up till now. These include the Malta-Sicily Escarpment (MSE), the Ionian Abyssal Plain (IAP), the Malta Plateau, the Malta Graben, and the Gela Basin. A discussion of the submerged terrestrial landscapes of the Maltese Islands is also given. With sea levels rising, the general interest in underwater landscapes and their exploration is also expected to increase in the future. 13