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As part of the day, there will be a chance for attendees to present their own science as part of our poster competition. The rules of the competition are outlined below, and it will be judged by 4th year undergraduates.
Abstract submission for the competition is now closed.
Aisling Bergin
Space weather events can cause disturbances in the Earth’s magnetosphere and ionosphere. Severe disturbances can cause disruption to electrical power systems, aviation, communication systems and satellite systems. Magnetometer stations on the ground are used to monitor and specify changes in the magnetosphere-ionosphere system. Geomagnetic indices based on measurements from these stations are used extensively and they have been recorded for many decades. Two examples are AE and DST, which are indices designed to measure the evolution and intensity of the auroral electrojets and the ring current, respectively. The SuperMAG collaboration have made new versions of these indices available. They are based on a larger number of magnetometer stations than the original AE and DST indices. We carry out a statistical comparison between the traditional and updated indices to identify how improved spatial resolution affects the indices.
Alice Selby
Memristance in nanowire networks arises from each individual nanoscale junction changing in response to voltage stimuli, leading to an overall network change in conductivity dependent upon the number and weight of junctions. Multiple conductive pathways mimic ionic signaling between neurons. Although these devices have demonstrated memristive I-V sweeps, there has been little study on the more biologically relevant pulsing of networks. We show that dropcast nanowire networks clearly demonstrate current-driven memristance with high on/off ratios, up to 10^6, along with nanosecond pulse response. Networks were shown to be electroforming friendly with one I-V sweep setting the network at low voltages. Nanowire network responding to pulsed electrical stimuli in lateral electrode configurations allow for not only emulation of synapses but integration in future cross-disciplinary work, due to the exposed memristive interfaces.
Amra Ali Alhassni
In this work, we investigated the use of Bi as surfactant, which provides an effective method to reduce the density and improve the optical quality of InAs QDs. For this purpose, two types of InAs QDs samples were grown at similar conditions at low temperature (3500C) on (001) GaAs substrate by using solid source MBE with and without the presence of Bi-contained layer. The PL emission was studied as a function of laser power at 10K. Two sets of InAs QDs were observed in the Bi-free and Bi mediated grown samples with energies of 1.32eV and 1.35eV, and 1.26eV and 1.36eV, respectively. In addition, PL peaks were detected in both samples at 1.49eV and 1.4eV, which were assigned to GaAs and InAs wetting layer, respectively. It was found that the use of Bi as surfactant resulted in a substantial improvement of the PL intensity, e.g. the peaks due to large and small QDs at 1.26 eV and 1.36 eV improved by a factor of 5 and 1.5, respectively, under a laser excitation intensity of 7mw at 10K. The presence of Bi caused a large red shift of the PL energy of the large QDs (from 1.32eV to 1.26 eV) and no appreciable shift was observed of the smaller QDs (from 1.35eV to 1.36 eV).
Beth Hampshire
Muons have a mass of around 207 times greater than that of an electron whilst maintaining the same spin. This characteristic leads to negative muons being a good probe for elemental analysis beyond the surface of samples, completely non- destructively. Upon capture of the negative muon by an atom, it displaces an electron and cascades through the modified energy states towards the nucleus. Through each transition, a muonic – X- ray is emitted that is characteristic of the atom that captured it and the transition taking place, which is a similar effect to XRF. The muonic- X-rays have energies in the keV – MeV range, which is greater in energy than an electronic-X-ray. As a result, it is possible probe beneath the surface without significant absorption of the muonic-X-rays by the sample, thus providing a depth-dependant, non-destructive elemental analysis technique. Here, we present work done on developing the negative muon instrument at ISIS on the RIKEN-RAL beamline with results on silver Roman coinage. Eight coins were measured, with a depth profile of the surface enriched layer and reveal the composition of the original Ag-Cu alloy.
Bhagyashree
The lack of symmetry between matter and antimatter in our Universe demands understand-ing of the CP violation phenomenon. LHCb is the first experiment that has the capability to produce and detect b baryons in an unprecedented quantities and in a wide range of decaychannels. The analysis of the data obtained from LHCb can be used to study the CP Violation effects and possibly, reveal the new physics beyond Standard model.
Bluebell H. Drummond
Thermally-activated delayed fluorescence (TADF) organic molecules emit visible light more effectively than normal organic fluorescent emitters, making them attractive materials for organic light-emitting diodes. TADF emitters comprise an electron-withdrawing unit covalently linked to an electron-donating unit. The separation of these molecular units affords lowest lying singlet and triplet states that are close in energy. The small singlet-triplet exchange energy means that intersystem crossing (ISC) between the singlet and triplet states is thermodynamically allowed, facilitating emission from the usually dark triplet state and boosting electroluminescence efficiency. Transient electron spin resonance (trESR) measurements allow us to probe the lowest lying triplet state (T1) in TADF emitters. From trESR measurements we can determine the mechanism through which T1 is populated via ISC from the photoexcited singlet (S1). trESR is therefore an attractive tool with which to study TADF emitters, as the optimal mechanism for singlet-triplet interconversion and mixing is still unconfirmed. Through modification of the molecular structure we modulate the singlet-triplet energy gap within a set of closely-related organic emitters. We studied how the changes influenced the emission mechanism and photophysical properties of the compounds. trESR measurements of these molecules demonstrate that as the singlet-triplet gap reduces from 100s to 10s of meV, an evolution occurs from ISC mediated by spin-orbit coupling to ISC mediated by hyperfine coupling. This study provides evidence that the energetic ordering of the excited states determine which coupling mechanism dominates, and that both spin-orbit coupling and hyperfine coupling mechanisms can be active within a given TADF emitter.
Charlotte Henshaw
Polymer microparticles are of great interest in a range of industries, for example: those concerned with drug delivery and cell growth. Flow-focussing microfluidics allows monodispersed particles to be produced, a great advantage over traditional mixing methods. However, this usually requires extensive “trial and error” based optimisation.
Here micropipette manipulation has been used to measure key parameters of a water/hexanediol diacrylate: Hydroxy-3-phenoxypropyl acrylate: Poly(ethylene glycol) methacrylate system. This allowed the optimum surfactant (Hydroxy-3-phenoxypropyl acrylate: Poly(ethylene glycol) methacrylate) concentration to be found. Using this it was then possible to predict the range of flow rates that should be used in the microfluidics to produce a stable stream of particles. Comparing to experimental tests show this to be a promising method to reduce future optimisation times.
Clár-Bríd Tohill
The properties of Galaxies at very high redshifts are largely unknown mostly due to detection limits of extragalactic surveys and lack of detailed spectra, hence they can be hard to classify. One proposed method is to classify these galaxies by their morphological parameters alone which can be extracted from a single image. The parameters that we investigate are the Concentration (C) of light and the Asymmetry (A) of the galaxy.
While small changes in these parameters can be hard to see by eye, they can be easily picked up by machine learning algorithms which are faster than most traditional methods. We employ a convolutional neural network (CNN) that is trained on a subset of galaxies from the CANDELS GOODS fields for which these parameters are already known. We then investigate how well the network can reproduce these values to determine if it would be a suitable method for large scale surveys.
Devika Tharakkal
The multi-phase interstellar medium (ISM) which exists in the space between the stars is composed of hot and cold atoms, molecules and dust. It also contains cosmic ray (CR) electrons and protons which are relativistic charged particles. The magnetic field in the ISM is random in nature. Understanding the propagation and distribution of CR particles is vital to see if there is any correlation between cosmic rays and magnetic fields. In the turbulent interstellar medium (ISM), random magnetic fields can form magnetic mirrors, which act as traps for CR particles. We use test particle simulations of CR electrons and protons in the presence of random fields to investigate the distribution of the CR particles in the random magnetic fields.
Ellie Fradgley
Light is used as a measurement tool in many systems: from the imaging of biological tissues to the detection of gravitational waves. A fundamental limit is imposed on such measurements due to the quantum nature of light. The random distribution of photons leads to small fluctuations in intensity, leading to fluctuations which are commonly referred to as shot noise. This noise can be reduced using a process called squeezing, in which correlated pairs of photons are created, thus reducing the randomness of their distribution in the light. Through further optical manipulation, the intensity fluctuations in the beams can be removed almost entirely, resulting in light with a 'smooth' intensity profile which can be used to exceed the standard quantum noise limit. However it is only in the special case where the intensity is 'smoothed' across the whole transverse profile of the beam, such as when using an optical process called four wave mixing, that the light becomes useful for applications such as imaging. In this case, the light is said to be squeezed in multiple spatial modes.
Emily Ferris
Ultra-luminous AGNs selected by combining mid-IR WISE and NVSS radio data, radio-WISE galaxies (RWGs) are a rare and extreme population of highly-obscured galaxies with young, compact radio jets exciting their ISM. Dominated by extreme mid-IR warm dust emission, they are radiatively efficient and with potentially merging morphologies, may represent an unknown and key phase in quasar evolution. We have observed 27 of these radio-WISE galaxies using VLT instruments X-shooter and ISAAC at excellent seeing, and present NIR spectroscopy of these extremely luminous sources (bolometric luminosities of ~10^47 erg/s, some of the brightest in the universe) across a wide redshift range of z = 0.88 – 2.85. Using the 15 detected broad [OIII]λ5007 emission lines, we calculate lower limit black hole masses of log(MBH) = 8.2 - 9.5 M☉ with corresponding host masses of log(M_Host) = 10.7 - 12.0 M☉ assuming black hole-host co-evolution. We also derive 2 additional independent mass estimates using the 14 Hα and 7 Hβ emission line detections, along with using these Balmer lines and the Cardelli 1989 extinction law to estimate how obscured our hosts are.
Emma Willett
The ages of low-mass stars have wide-ranging applications – from studies of galactic structure and evolution to surveys of exoplanet systems. One of the limiting factors in obtaining precise and accurate ages for these stars is the poor constraints on their helium mass fraction, Y. The value is commonly estimated by applying the helium-to-metal enrichment ratio, DY/DZ, to obtain Y from the measured metal mass fraction, Z. However, the value and behaviour of DY/DZ is uncertain. I will present the results of a study using the luminosity of red clump (low-mass, core helium-burning) stars as a proxy for Y, from which DY/DZ is constrained. The approach combines asteroseismic results from Kepler with spectroscopy from APOGEE and astrometry from Gaia DR2 to allow red clump stars to be used in this way for the first time.
Hannah Hatcher
THz radiation (10^12 Hz) is of interest for studying the skin of living subjects due to its high sensitivity to water content and unlike some other forms of radiation it is non ionizing. However due to the high sensitivity to water content in the skin there are many variables which will affect the measurement such as temperature, humidity and the contact pressure on the imaging window. To control the contact pressure a pressure sensor is integrated with the imaging system to help the subjects give consistent measurements and record the measured pressure to aid data processing. A protocol is proposed to help achieve repeatable results and to remove the effects of the natural variation of the skin through the course of the day. This technique is able to quantify the changes induced in the skin following the application of a moisturising skin product. It is hoped that the development of a standardised protocol will open doors to further applications of THz imaging for skin diagnostics such as skin cancer diagnosis.
HAYAT ABBAS
Hybrid quantum systems are a hot topic, especially transducers that allow us to interface quantum noise properties of an object of one type to quantum noise properties of an object of another type. Quantum transducers map the quantum noise of the position of a membrane to the degree of freedom in the polarized light. A position-to-polarization converter is formed by a micromechanical membrane inside a high finesse optical resonator and a displacer that splits a laser beam spatially into two orthogonally polarized components. Both beams are focused onto an optical resonator. Each time a laser beam traverses a transparent, micromechanical membrane that sits in the resonator and this will cause a significant phase shift that depends on the membrane’s position. The light leaving the resonator can be recombined with the reference and form a single beam with modulated polarisation. Thus, obtaining signals to observe the motion of a membrane and analysis the signal noise are possible. The properties of membrane will alter the polarization of the laser light and can be mapped at the quantum noise level. To achieve this, test measurements from two aspects are required; alignment precision and measuring the quantum shot noise using the balanced photodetector. Alignment precision shows how sensitive our measurement is and provides us with the needed lens displacement in millimetres. Furthermore, detection must be quantum shot noise limited to prove that the power spectral density depends on the conversion gain, which is found to be 4.5x105V/W in the frequency range 1kHz-13kHz.
Rebeckah Trinder
Nuclear medicine is commonly used in cancer treatments and imaging. The combination of cancer therapy and diagnostic (theragnostic) procedures are presently being used in hospitals. Currently, two different elements are commonly used, however the use of theragnostic techniques could be improved by the use of different radioactive isotopes of the same element as this will reduce the uncertainty in targeting and imaging areas of cancer cells. The element terbium has four isotopes which could be used in nuclear medicine as theragnostic isotopes. Production of these isotopes using the MC40 Cyclotron at the University of Birmingham is currently being investigated. Results from the initial experiments will be presented.
Kate Brown
At the end of the twentieth century, Stamper-Kurn et al. [1] demonstrated the reversible formation of a Bose-Einstein condensate within a 3D, harmonically trapped gas. This was achieved by varying the chemical potential of the system. Here, we extend this pioneering work to a 2D, homogeneous gas. We show how periodically quenching the interaction strength of such a system results in the reversible crossing of the Berezinskii-Kosterlitz-Thouless phase transition. This topological phase transition was the subject of the 2016 Nobel Prize in Physics.
[1] Stamper-Kurn, D. M. et al., Phys. Rev. Lett. 81, 2194, 1998
Lucy Downes
Terahertz (THz) radiation lies on the electromagnetic spectrum between the microwave and infrared regions, falling in the gap between optical and electronic detection techniques. Despite THz radiation having applications across areas including security, biomedical and quality control, a lack of fast detection and imaging techniques has meant that it has not seen widespread commercial uptake. Atoms have been used to sense a range of electromagnetic fields at microwave, radio and THz frequencies, but their application to imaging has so far been limited. Here we present a new and novel THz imaging system capable of capturing images 100 times faster than the prior state of the art. Our simple and versatile technique is based on efficient THz-to-optical conversion in a room-temperature atomic Rydberg vapour, allowing THz images to be captured using conventional camera technology. We demonstrate and characterise a 1cm^2 sensor with 1mm spatial resolution and sensitivity comparable to the best cryogenic sensors. We show that this system is capable of image capture at 3000 frames per second and describe how this is relevant across a wide range of scientific, industrial and commercial settings. Finally, we highlight future improvements to the system that could enable image capture at framerates over 10 kHz.
Maryam Mushabbab Al Huwayz
In this research, the electrically active defects in InAs quantum dots (QDs) based intermediate band solar cells (IB-SC InAs-GaAs) grown by Metal-Organic Vapor-Phase Epitaxy (MOVPE) technique at different temperatures are investigated. Based on the current-voltage (I-V) measurements, it was observed that the samples grown at high temperature (700 oC: sample pin_700) have better I-V characteristics than those grown at low temperature (630 oC: sample pin_630). In contrast, the capacitance-voltage (C-V) measurements indicated that the doping concentrations were lower for the pin_700 sample than for the pin_630 sample.
In order to identify the behaviour of defects close to and away from the interface of these p-i-n solar cell devices, Deep Level Transient Spectroscopy (DLTS) and Laplace DLTS measurements were performed at different reverse biases. A sharp DLTS peak at Vr= -1V and -4V was observed in the pin_700 device while four broad peaks have been detected in pin_630 at Vr= -1V. The different behaviours of the two samples could be attributed to the different growth temperatures.
Morag Williams
The Compact Linear Collider (CLIC) is a proposed future high-luminosity, high-energy linear electron-positron collider based at CERN, Switzerland. The R&D programme of CLIC aims to fulfil the ambitious requirements of the inner detectors. For example, the pixelated vertex detector requires a single point resolution of 3um and a timing resolution of 5ns. The CLICpix2 small-pitch, hybrid readout ASIC has been produced in a 65nm commercial CMOS process to target the vertex detector requirements. CLICpix2 samples have been bump-bonded to planar silicon sensors and the quality of this bonding was assessed using laboratory measurements. All assemblies that were found to be of high quality were then tested with an incident particle beam and their resolution, efficiency, and performance were determined. These CLICpix2 laboratory and test-beam results are presented in this poster, with an emphasis upon recent results and developments.
Rosalyn Pearson
Protons are complicated clusters of fundamental particles like quarks and gluons known as partons. Parton distribution functions dictate the probabilities for what you will find when you look inside the proton, and are therefore of great importance in making predictions at the proton level. They are calculated in a global fit including a wealth of experimental and theoretical information. In the high precision era of particle physics, pinning down these functions is crucial, and this now necessitates recognising the influence of theory uncertainties in the fitting process. One major source is due to missing higher perturbative orders of theory. We estimate these uncertainties, check their form, and show that including them in a fit improves the quality of the result.
Saniya Khan
Convection is one of the fundamental mechanisms for energy transport in stars. It involves organised macroscopic motions of matter that, in addition to carrying energy, also constitute a very efficient mixing mechanism. Mixing processes beyond convective boundaries have significant implications on the predicted evolutionary path, lifetime, and chemical composition of stars, which may be incompatible with observations. However, the treatment of convective boundary mixing is among the main uncertainties in models of low-mass stars: what is the physical nature of these mixing processes? to which extent are the chemical elements mixed? For this reason, theoretical stellar astrophysicists have been and continue working towards a better understanding of convection in deep stellar interiors.
Sofia Qvarfort
Is there any entanglement in the simplest ubiquitous bound system? We study the solutions to the time-independent Schrödinger equation for a Hydrogenic system and devise two entanglement tests for free and localised states. For free Hydrogenic systems, we compute the Schmidt basis diagonalisation for general energy eigenstates, and for a Hydrogenic system localised to a three-dimensional Gaussian wavepacket, we demonstrate that measuring its second moments is sufficient for detecting entanglement. Our results apply to any system that exhibits Hydrogenic structure.
Ting-Yun Cheng
The morphological classification of galaxies is a very important tool for understanding the history of galaxy assembly. It not only tells us about the evolution of galaxies, but it can also reveal the stellar properties of galaxies, and thus their histories. Since the pioneering work by Hubble 1926, nearby galaxies can be easily and clearly classified into two main types: early-type galaxies (ETGs), which include elliptical galaxies and lenticular galaxies, which are mostly massive, with older stellar populations, and no spiral structure; and late-type galaxies, which include spiral galaxies and irregular galaxies, often with spiral arms, and which consist of a younger population. These two types are the basic classifications of galaxies in local universe and have remained so for nearly a century.
Unsupervised machine learning, which is trained without any prior knowledge such as galaxy physical properties or galaxy types, provides a different perspective from human assessment and can potentially reveal an underneath pattern in galaxy morphological classification. In this work, we develop an unsupervised machine learning method composed of a newly machine learning technique - Vector Quantised Variational Autoencoder and clustering algorithms such as Hierarchical Clustering and Bayesian Gaussian Mixture models, and apply this to the galaxy imaging data from the Sloan Digital Sky Survey. Without labels defined by human inspection, we explore the galaxy morphology unbiasedly by looking at them through these “machines’ eyes” that leads us to gain a new perspective in this field.
V. Vilasini
Understanding cause-effect relationships is a crucial part of the scientific process, these can be described using directed acyclic graphs or causal structures. Bell’s theorem shows that within a given causal structure, classical and quantum physics impose different constraints on the correlations that are realisable, thus making it possible to certify the “quantumness” of a causal structure from observed correlations. This is a fundamental feature that also has important technological applications.
While Bell’s proof shows that this works well for certain causal structures, it is in general it is difficult to distinguish the set of classical and quantum correlations within any given causal structure. Here we investigate a method to do this using entropies as a measure of correlation rather than probabilities. In particular, we use Tsallis entropies since the better known Shannon entropies were previously found to have certain limitations. We derive constraints on the Tsallis entropies of systems that are implied by classical (and certain quantum) causal structures involving those systems. We find that the number of independent constraints needed to characterise the causal structure is prohibitively high that the computations required for the standard entropy vector method cannot be employed even for small causal structures. Instead, without solving the whole problem, we find new Tsallis entropic inequalities (analogous to Bell’s inequalities) for the Triangle causal structure by generalising known Shannon inequalities. Our results reveal new mathematical properties of classical and quantum Tsallis entropies and highlight difficulties of using Tsallis entropies for analysing causal structures.
Zoë Davidson
Plasma – the fourth state of matter – occurs within many natural phenomena in our universe, such as stars and the Aurora Borealis. Plasma has a unique set of properties which (if well-tuned) can act as a mini particle accelerator. Excitingly, this is something we can generate and apply in the laboratory by using high-power laser pulses. High-power, because these pulses can reach intensities billions of times greater than all the sunlight incident on earth, by delivering a compressed pulse with 10,000 times more power than the National Grid in just 1 picosecond, within a focused spot diameter of a few microns. How might we observe and tune pulses this fast, small and powerful so that we can compete with conventional particle accelerators? This is something I’ve explored throughout my PhD. Here I introduce the concept behind a novel multichannel tunable optical probe design we implemented to provide deeper insight into the ultrafast evolving plasma dynamics that are key to particle acceleration. By encoding multiple laser pulses we can probe, and therefore observe for the first time, the evolution of a single high-power laser pulse interaction with plasma up to 250 billion frames per second, and I’ve even made a flicker book to prove it. The new insights enabled by this probe are guiding the way to better control of compact laser-driven particle accelerators, which seek to address some of the biggest challenges we face today: clean energy, disease and a more complete understanding of our place in the universe.
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