PhD opportunities

Projects

Deadline: Submit your application by 31 May 2017 to start in Autumn 2017 unless the project states otherwise

On this page you can find out about PhD opportunities currently available in physics and astronomy. Click on a research area or a project title below to find out more.

We have a limited number of departmental and research council scholarships available each year, to cover tuition fees and living expenses for some of our PhD students. We also accept applications from students who are able to fund themselves.

Funding your PhD
See also: Tuition fees

It is a good idea to contact the supervisor of any PhD opportunity you want to apply for, before you submit your application, as they may also be able to advise you on other sources of funding.

Once you have identified a project, a supervisor and a source of funding, you can complete the University's postgraduate online application form.

Postgraduate online application form

If you would like any more information or have any questions, please contact us.

Email: physics-phd@sheffield.ac.uk
Telephone: +44 (0)114 222 3789

Do you have your own idea for a project?

Find a potential supervisor by visiting our research webpages. Contact a member of academic staff to find out about PhD opportunities in their area.

Research

Centres for Doctoral Training

Other funded PhD opportunities are available through the Centres for Doctoral Training that our staff contribute to. Visit the webpages for these centres to find out more about their projects.

Centres for Doctoral Training at the University of Sheffield

Entry requirements

We usually ask for an upper second class (2:1) honours BSc or MSc degree in physics or engineering.

Our decision on whether to offer you a place will also be based on the research proposal or personal statement you submit, your CV and references, and any interviews you complete. Students will also need to meet our English language requirements, and international students will need to get clearance through the Academic Technology Approval Scheme (ATAS). Find out more about English language requirements and ATAS on our webpage for international students:

International students


Astronomy and astrophysics

For general enquiries contact: Dr James Mullaneyj.mullaney@sheffield.ac.uk

Find out more about astronomy and astrophysics research

High-speed astrophysics with HiPERCAM, ULTRACAM and ULTRASPEC

HiPERCAM, ULTRACAM and ULTRASPEC are high-speed cameras built by Sheffield/Warwick/UKATC for the study of astrophysics on fast timescales. Extreme astrophysical conditions can be found in our Galactic neighbourhood by studying the compact remnants of stars: white dwarfs, neutron stars and black holes. The dynamical timescales of these compact objects range from seconds to milliseconds, which means that much of the variability observed from them occurs on such fast timescales. Existing common-user instrumentation on the world's major telescopes is unable to obtain high time-resolution data, which is why we have developed HiPERCAM, ULTRACAM and ULTRASPEC. The aim of this PhD project will be to exploit these unique instruments on the 10.4m GTC, 4.2m WHT, 3.5m NTT and 2.4m TNT to study physics in extreme conditions, such as accretion onto black holes, the structure of white dwarfs, the evolution of close binary stars, and the physics of pulsars.

Contact: Professor Vik Dhillon (vik.dhillon@sheffield.ac.uk) or Dr Stuart Littlefair (s.littlefair@sheffield.ac.uk)

Masses of White Dwarfs in Interacting Binary Stars

Type IA supernovae are the key to our understanding of the expansion of the Universe. Surprisingly, then, we still do not fully understand their origin. It is widely recognised that type IA supernovae come from white dwarfs being driven above the Chandrasekhar mass, but there is no consensus on how this happens. Candidate progenitors include the merger of two, lower mass, white dwarfs, or white dwarfs accreting rapidly from sub-giant stars. Neither of these two models can explain all the observations. One channel that has often been ignored is a white dwarf accreting from a low-mass star. These objects, known as catalcysmic variables (CVs), are thought not to be IA progenitors as the mass accreted by the white dwarf is expected to be expelled in Nova eruptions. However, the masses of white dwarfs in CVs is larger than isolated white dwarfs, suggesting that perhaps the white dwarfs in CVs can grow in mass after all. In this PhD, you will use light curve modelling to measure the white dwarf masses in a large sample of CVs to test the idea that CVs may, after all, be IA progenitors.

Contact: Dr Stuart Littlefair (s.littlefair@sheffield.ac.uk)

The environments of star and planet formation

Young stars are often found in high-density environments, this means that encounters between young stars can be common and this will change their binary properties and affect planet-forming discs. A PhD would involve investigating various computational and statistical aspects of young stars and their environments. These include dynamical and hydrodynamical simulations of stellar dynamics, statistical measures of complex distributions, examining and interpreting both observational, simulated and 'fake' data.

Contact: Dr Simon Goodwin (s.goodwin@sheffield.ac.uk)

Single or binary origin of Wolf-Rayet stars? Which mode is dominant

Wolf-Rayet stars are the evolved descendants of massive OB stars, revealing the products of H or He burning at their surfaces. Their hydrogen envelopes are stripped away either through dense stellar winds of very high mass stars or via mass transfer to the initial secondary star in a close binary. This project will exploit the environment of Wolf-Rayet stars in the Milky Way, Magellanic Clouds and other nearby star forming galaxies to assess which of these mechanisms is dominant.

Contact: Professor Paul Crowther (paul.crowther@sheffield.ac.uk)

How do supernovae explode?

Supernovae are some of the most important objects in the Universe. They are responsible for sculpting the shapes of galaxies, releasing heavy chemical elements into the Universe and can serve as cosmological lighthouses for measuring distances. Despite their utility, the exact nature of the explosion behind these events is one of the biggest unknowns in modern astronomy and holds the key to understanding some of the most extreme physical environments found in the Universe. This project is concerned with measuring the shapes of distant supernovae, despite them being too far away for us to see their shapes through direct imaging. The amount of polarization measured for these events allows us to conduct 3D tomography to reconstruct their shapes and identify the physics of the explosion mechanism. This project is primarily computational, building radiative transfer models to study how light generated in the explosion escapes from the ejecta and how the shape of the ejecta is imprinted on the polarization.

Contact: Dr Justyn Maund (j.maund@sheffield.ac.uk)

Machine Learning for Transients

How do people first learn to spot patterns? How people separate things into objects that look the same and objects that look different? How do people identify which particular characteristics are important for discriminating between different types of objects? In this project we will consider machine learning and its application to the observations of transients, that are now being produced by the first generation of survey telescopes and will become progressively important in the next decade with the advent of the Large Synoptic Survey Telescope (LSST) and the European-Extremely Large Telescope (E-ELT). At Sheffield, we have a head start in the field, being a partner in the upcoming GOTO (Gravitational Wave Optical Transient Observatory), which will detect a large number of brand new types of transients. This project is primarily concerned with developing unsupervised learning algorithms to mimic the way in which humans learn when given a new set of information they’ve never seen before. In the case of supernovae, the classification scheme has been developed over the last 80 years, with new branches being proposed on a regular basis. This project aims to answer the question: what is the most natural way to differentiate and classify different types of transient?

Contact: Dr Justyn Maund (j.maund@sheffield.ac.uk)

Where do supernovae explode?

The deaths of massive stars are marked by dramatic explosions known as supernovae. These massive stars are also very young and can be found close to the place where they formed and in the vicinity of other massive stars (though slightly less massive than the one that exploded). A fundamental question in the field of supernova research is which types of star will explode as supernovae of a given type. This project aims to utilise observations of star forming regions in nearby galaxies made with the Hubble Space Telescope. Spanning from the ultraviolet to near infrared wavelengths, these images of individual stars provide a “fossil” record of the births and deaths of massive stars. Bayesian tools will be developed and applied to this data to understand the temporal and spatial distributions of the stars. Supernova-selected populations provide a unique window on massive star formation and evolution, that can also reveal the origin of the diversity of massive star supernovae and the physics of the explosion itself.

Contact: Dr Justyn Maund (j.maund@sheffield.ac.uk)

What governs the growth of black holes

Producing the definitive range of intrinsic AGN templates (lots of data reduction, moderate computation).
One of the most frequently used ways to disentangle light from AGN and their host galaxies is to analyse their Spectral Energy Distributions, or SEDs. These SEDs describe the energy output of the AGN and galaxy at every wavelength. Commonly, we use sets of AGN and galaxy templates to fit the SEDs which, effectively, separates out the light from each. While a lot of effort has focussed on defining galaxy templates, the AGN templates remain very poorly defined. The aim of this project is to use data from X-ray, optical and infrared telescopes to define the definitive set of AGN templates.

Contact: Dr James Mullaney (j.mullaney@sheffield.ac.uk)

How good is the far-IR as a tracer of star formation activity in AGN host galaxies?

In order to understand the links between black hole growth and galaxy evolution it is crucial to have a "clean" indicator of the star formation activity in host galaxies of active galactic nuclei (AGN). The thermal far-infrared continuum emission has been proposed as such an indicator, however recent work by the Sheffield group has suggested that a substantial proportion of the far-IR continuum may radiated by kpc-scale dust that is heated by the AGN rather than by regions of star formation. This observational project will use deep observations taken with the HST, Spitzer, Herschel and ALMA telescopes to directly quantify the contribution of AGN heated dust at far-IR wavelengths, and hence assess whether the far-IR continuum is truly a good indicator of star formation activity in AGN host galaxies.

Contact: Professor Clive Tadhunter (c.tadhunter@sheffield.ac.uk)

How are AGN triggered?

To accurately incorporate active galactic nuclei (AGN) into galaxy evolution models it is important to understand how and when AGN are triggered as their their host galaxies grow via gas accretion, and also whether the triggering mechanism depends on the luminosity of the AGN. This observational project will involve using deep imaging and spectroscopy observations of samples of nearby AGN to thoroughly investigate AGN triggering mechanisms.

Contact: Professor Clive Tadhunter (c.tadhunter@sheffield.ac.uk)

Star formation with Gaia

One of the main unsolved problems in star and planet formation is to determine the typical initial conditions (density, velocity field) of star formation. Planets form at the same time as stars, so the initial conditions of star formation may significantly affect planet formation. New observational facilities, such as the Gaia satellite and ground-based spectroscopic surveys, are providing a wealth of information on the kinematics of young stars in star-forming regions. This PhD project will combine numerical simulations with the first results from Gaia and the Gaia-ESO survey to determine the initial conditions of star formation in nearby regions of the Milky Way using kinematics.

Contact: Richard Parker (r.parker@sheffield.ac.uk)


Biological physics

If you are applying for one of these projects, you may be able to apply for the a departmental scholarship or EPSRC studentship to cover your tuition fees and living expenses.

Funding your PhD

For general enquiries contact: Professor Jamie Hobbsjamie.hobbs@sheffield.ac.uk

Find out more about biological physics research at the Imagine: Imaging Life website

Molecular resolution microscopy for understanding host-pathogen interactions and anti-microbial resistance

Anti-microbial resistance (AMR) is a growing societal threat that needs to be tackled now if we are going to avoid major public health issues in the next few decades. Recent developments in microscopy techniques and physical methods, in particular super-resolution optics, atomic force microscopy (AFM) and cryo-electron microscopy, provide a range of new approaches for understanding how bacteria interact with the host (e.g. us) and ultimately why some infections are cleared by our immune response and others are not. This project aims to bring these new approaches together to tackle this challenge, making use of the unique facilities available in Sheffield (http://www.imagine-imaginglife.com/) in combination with extensive expertise in host-pathogen interactions and AMR (http://www.floreyinstitute.com/). The project is funded as part of an MRC AMR network, and the successful student will form part of an interdisciplinary cohort across the universities that form the network (Sheffield, Edinburgh, Newcastle and Birmingham). This position is suitable for a physical scientist (physicist, chemist, biophysicist etc) with an interest in applying their knowledge to biological systems, or a biological scientist with an aptitude for physical and technological approaches.

Contact: Professor Jamie Hobbs (jamie.hobbs@sheffield.ac.uk)

Theoretical modelling of malaria invasion of red blood cells

The malaria parasite invades red blood cells in the host and changes the shape and mechanics of these cells. The parasite reproduces inside the red blood cell until the host cell bursts releasing the parasites to infect more host cells. This aim of this theoretical project is to calculate how the malaria parasite enters the host cell and changes the shape and mechanics of these red blood cells. It is known that the parasite uses actin and myosin to push itself into the host cell. These are the same molecular ingredients used for classic cell motility but the structure of the actin and myosin machinery is known to be quite different. The details of how this machinery works are not yet well understood and theoretical modelling will help in this goal. Red blood cells have a characteristic biconcave disk (doughnut) shape. The inner surface of their membrane is covered with a network of a cytoskeleton protein called spectrin which in turn binds to the actin cytoskeleton. These cytoskeleton filaments maintain the red blood cell's shape and mechanical stability. We will theoretically model this cytoskeleton and calculate the forces involved when malaria parasite alters the red blood cell shape and mechanics. This project will be conducted in collaboration with partners in South Africa and therefore may involve travel there.

Contact: Dr Rhoda Hawkins (rhoda.hawkins@sheffield.ac.uk)

How do immune cells eat microbes?

The Florey Institute (http://www.floreyinstitute.com) and Imagine: Imaging Life (http://www.imagine-imaginglife.com) are long term strategic initiatives at the University of Sheffield (2022 Futures) that provide a platform for ambitious research growth in areas that the University of Sheffield is recognised for internationally. The Florey Institute aims to create a world-leading focus on antimicrobial resistance and host-pathogen interactions, from fundamental science to translation. Imagine: Imaging Life aims to combine and harness cutting-edge imaging technologies in super-resolution microscopy, electron microscopy and atomic force microscopy to address key biological questions. This scholarship, as part of the Global Strategic Alliance programme, will position the student in a thriving research environment that may provide international opportunities for training and career development.

Macrophages are immune cells that directly kill infectious microbes. Ingestion (phagocytosis) of microbes is needed for the clearance of infection. Despite the importance of phagocytosis there are many fundamental aspects that are not understood.

This project is interdisciplinary and would suit an applicant from either a biological or physical sciences background.

In this project we will focus on how the size, shape and stiffness of microbes affects the ability of macrophages to ingest them. We will use cutting edge microscopy (super resolution STORM and SIM, electron, and light sheet microscopy) combined with biophysical modeling to define the important parameters governing the mechanics of phagocytosis. The recent revolution in optical microscopy allows us to beat the diffraction limit, enabling us to image individual fluorescent molecules in cells. Where necessary in the project we will development bespoke microscopes. We will use medically relevant microbes of different shapes, sizes and surface properties (e.g. Staphylococcus aureus and Mycobacteria tuberculosis). These measurements will inform our theoretical models predicting success of phagocytosis for different microbes.

For more information, please see: http://www.imagine-imaginglife.com/phd-studentship-sj.html

Please note the closing date for applications for this project is 27/03/2017.

Contact: Dr Simon Johnston (s.a.johnston@sheffield.ac.uk) or Dr Rhoda Hawkins (rhoda.hawkins@sheffield.ac.uk)

Understanding chromatin organisation in cell nucleus: multiscale approaches to stem cell biology

Take a bunch of different coloured spaghetti and bring them to a boil in a pot. The spaghetti ends up in a gooey mess all entangled. In contrast, human chromosomes, that may be visualized as “cellular spaghetti” is organised in distinct regions or “territories” inside the cell nucleus. How the cell, formed of compliant parts, achieves such tight control is not yet clear despite several experimental and theoretical studies. This is a theoretical project and will focus on extending ideas of polymer physics and non-equilibrium statistical mechanics to understand chromosome organization inside the cell nucleus along its development pathway. A coarse-grained model of chromosome organization that leads to gene regulatory networks at the macroscale will be developed. This would also help understand how stem cells are intrinsically different from differentiated ones at the microscopic level and pave the way forward for a statistical understanding of stem cell biology, and chromosomal abnormalities.

Contact: Dr Buddhapriya Chakrabarti (b.chakrabarti@sheffield.ac.uk)


Inorganic semiconductors

Our highly active group has more than 20 PhD students involved in research on a variety of topics in the area of semiconductor nanostructures. In 2017, we are seeking students for the following projects, with funding available for both UK and EU candidates. At any particular time there may also be associated postdoc positions.

For general enquiries contact: Professor Maurice Skolnickm.skolnick@shef.ac.uk

Find out more about inorganic semiconductors research

Semiconductor quantum optical circuits

As a result of a five year large grant award (find out more) from the UK funding agency, EPSRC, several positions are available in highly topical areas of semiconductor physics and optics research. These include the physics of the first semiconductor quantum optical circuits, novel methods for spin readout and new types of single photon sources. All topics have the opportunity for advanced fabrication of nanoscale structures, and involve participation in research at the leading edge of semiconductor physics and photonics.

Contact: Professor Maurice Skolnick (m.skolnick@shef.ac.uk)

Photonics with 2D materials beyond graphene

Applications are invited for a PhD project in photonics with 2D materials beyond graphene. Two PhD positions are available as part of a new Marie Sklodowska-Curie Innovative Training Network 'Spin-NANO' led by Sheffield and including leading nano-physics groups in Europe. In this project the student will join an energetic team of 3 PhD students and 4 postdocs to work on exploration of optical properties of layered compounds and new devices comprising these materials. The isolation of single-atomic layer graphene has led to a surge of interest in a large family of layered crystals with strong in-plane bonds and weak, van der Waals-like, interlayer coupling. Heterostructures made by stacking different atomically thin 2D crystals provide a platform for creating new artificial materials with potential for discoveries and applications. In this PhD project you will study 2D materials with a wide range of fundamental properties, ranging from semi- to superconductors. You will work on advancing fabrication technology to explore the potential of van der Waals heterostructures in photonics applications. You will perform advanced optics experiments in the state-of-the-art laboratories of the Sheffield group, work on novel device fabrication in the modern clean room and collaborate with leading groups in 2D physics and technology.

Contact: Professor Alexander Tartakovskii (a.tartakovskii@sheffield.ac.uk)

More about research into 2D materials in Sheffield

Magnetic resonance studies of semiconductor quantum dots for quantum information applications

This experimental project focuses on electron and nuclear spin physics in nanometer-sized semiconductor quantum dots. Semiconductor quantum dots are a promising hardware for the emerging quantum information technologies: the spin wavefunction of the electron can be used to store and process quantum information. The interaction of the electron spin with the spins of atomic nuclei is a major challenge on this way. The aim of this project is to develop a state-of-the-art quantum logic gate where electron spin is isolated from nuclear spins using magnetic resonance pulses. A variety of experimental techniques will be involved in this work: optical spectroscopy and microscopy, radiofrequency and microwave magnetic resonance spectroscopy, low temperature (liquid helium) experiments and high magnetic fields.

Contact: Dr Evgeny Chekhovich (e.chekhovich@sheffield.ac.uk)

More about this research

Optical Quantum Information Processing

Information processing with light is ubiquitous, from communication, metrology and imaging to computing. When we consider light as a quantum mechanical object, new ways of information processing become possible. We can use quantum nonlocality (entanglement) to perform secure communication, high-precision measurements, high-resolution imaging, and even build a quantum computer that can perform certain important tasks much more efficiently than ordinary computers. A PhD in optical quantum information processing at the University of Sheffield can touch on any, some or all of these topics. We are investigating how quantum repeaters can extend the reach of quantum communication protocols and may some day lead to the Quantum Internet. We study how arrangements of light emitters can be used to monitor deformations of the material upon which they are placed with exquisite precision and how quantum measurement techniques can be used to measure very precisely the shape and size of objects. We are developing new ways of creating entanglement and nonlocality between atoms and photons in waveguides and on chips. This will allow us to reliably create the necessary resources for a large-scale quantum computer that can be connected to the Quantum Internet.

Contact: Dr Pieter Kok (p.kok@sheffield.ac.uk)

Theory of Quantum Microcavity Polaritons

Microcavities are dielectric structures which trap electromagnetic fields in a very small region of space. When this field is made to interact with a semiconductor material, the excitations of the system are 'particles' known as polaritons. Polaritons have many interesting properties; they undergo a condensation similar to a BEC, which shows behaviour analogous to a superfluid. In this project, we shall be looking at the quantum mechanical properties of the polariton condensate to investigate whether it can show interesting quantum optical behaviour such as squeezing. Although the project is theoretical, involving analytical and computational work, there is a strong experimental polariton activity in the department, providing plenty of opportunities to collaborate in developing quantum optical technologies. This project will suit a physics graduate with good mathematical abilities and some background in computational work.

Contact: Professor David Whittaker (d.m.whittaker@sheffield.ac.uk)

Optimised designs for fault-tolerant quantum computers

Quantum systems can store and process quantum information, opening up the prospect of new technologies that outperform conventional supercomputers in many areas. However, quantum information is more fragile than classical binary information, being more susceptible to noise and rapid degradation. To build a reliable device, quantum information must be stored within an abstract quantum codespace that protects it against noise. Quantum computers must also tolerate faults occurring while processing information. In this project, you will develop new techniques for fault-tolerantly storing and processing quantum information, using both analytic and numerical methods to assess their performance. I am looking for an enthusiastic student with a physics, mathematics or computer science degree. The student should also have some of the following desirable skills: a good undergraduate-level understanding of quantum mechanics, a strong mathematical background and/or experience programming and running numerical simulations (e.g. in C). For more information see http://earltcampbell.com/

Contact: Dr Earl Campbell (e.campbell@sheffield.ac.uk

Nanowire quantum dots for novel quantum emitters

Using advanced semiconductor epitaxial growth techniques it is possible to fabricate long, thin semiconductor wires with length exceeding 1µm and diameter less than 30nm. Inserting a small disk of a lower bandgap semiconductor within these nanowires produces a zero-dimensional structure, a quantum dot (QD). QDs have a number of unique properties and have been used to produce high efficiency lasers, sources of single photons and as elements suitable for quantum computing. Nanowire QDs offer a number of advantages over more conventional self-assembled QDs but are still a relatively immature field of study. The project will involve the study of physical processes in nanowire QDs using state-of-the-art optical spectroscopy. Working with groups at University College London and Warwick University the ultimate aim is to obtain a full understanding of the physical, electronic and optical properties of these novel structures and develop single photon sources and nanoscale lasers.

Contact: Professor David Mowbray (d.mowbray@sheffield.ac.uk

Nonlinear and quantum polaritonics

Recent advances in semiconductor nano-technology lead to a new generation of robust controllable structures where manipulation of coupling between light and matter can be performed on a submicrometer scale. In these structures novel quasiparticles-polaritons, which are a mixture of light and matter (electrons), can be created. Polaritons have very small effective mass and, thus, may condense in a single quantum state at high temperatures. This macroscopically occupied state has properties similar to those of atomic Bose-Einstein condensates. In addition, giant polariton-polariton interactions may results in a number of phenomena ranging from superfluidity of light, ultra-low power self-localised wavepackets (solitons) to generation of single photons and entangled photon pairs. Polariton physics in microcavities is very topical research which may find future applications in quantum optical computation. A particular emphasis in this project will be placed on optical experimental studies with the aim to control temporal and spatial phase information, and spin and statistical properties of polaritons in different geometries.

A successful candidate will join a well-funded and very active research group with a world-wide reputation for excellence (https://ldsd.group.shef.ac.uk/research/polaritons/). The group possesses a wide range of modern equipment to conduct advanced quantum optics experiments. During the project the student will also obtain full access to a state-of-the-art clean room facilities available in Sheffield.

Contact: Dr Dmitry Krizhanovskii (d.krizhanovskii@sheffield.ac.uk)


Particle physics and particle astrophysics

Our experimental work falls into four main categories: experimental high energy physics, the search for dark matter, neutrino astrophysics, and neutrino physics, including neutrino factory research and development.

For general enquiries contact: Professor Neil Spoonern.spooner@sheffield.ac.uk

Find out more about particle physics and particle astrophysics research

ATLAS: Search for additional Higgs bosons

The discovery of the Higgs boson by the ATLAS and CMS experiments at the LHC in 2012 has completed the particles predicted by the Standard Model (SM).

Nevertheless , the SM cannot be the end of the story for fundamental particle physics, as it leaves unanswered many questions, such as the lack of stability for the mass of the Higgs boson (the hierarchy problem), and an explanation for the Nature of dark matter and dark energy which seem to dominate in the Universe.

Many well motivated Beyond the Standard Model models (Supersymmetry, 2 Higgs Doublet models), predict the existence of extra heavier Higgs bosons. Different BSM models predict different production and decay rates, of these extra Higgs bosons to known particles, depending on the values of a few parameters. Therefore, to successfully discover or exclude these models a combination of different SM-like Higgs final states (e.g H->tau tau, H->4l , H->bb, H->\gamma \gamma etc) and unique BSM decays predicted or enhanced in BSM theories (e.g. A to Zh and H to hh) is imperative.

The focus of this project will be to either observe or put limits on the production rates of extra higher mass “heavy” bosons predicted by theories beyond the SM. The extracted results can be then interpreted in the context of BSM benchmark scenarios like hMSSM or Mhmod. The proposed search for extra Higgs bosons currently constitutes a major probe for physics beyond the SM in the LHC.

Contact: Dr Christos Anastopoulos (c.anastopoulos@sheffield.ac.uk) and Dr Trevor Vickey (t.vickey@sheffield.ac.uk)

ATLAS: Searching for Di-Higgs Boson Production

It's possible that the 125 GeV Higgs boson discovered by the ATLAS and CMS Experiments is only one of several neutrally-charged Higgs bosons predicted by theories beyond the Standard Model. Many of these theories predict the existence of a more massive Higgs boson, H, that is able to decay into two lighter 125 GeV Higgses. The student will develop analysis strategies to search for the production of two neutral 125 GeV Higgs bosons (H to hh), and then carry out these search strategies on the ATLAS Run-II 13 TeV collision data. Searches will focus on a final state where one of the Higgs bosons decays into two tau leptons, and the second Higgs boson decays to a pair of bottom quarks. The student will also use this same final state to explore the Higgs boson self-coupling (h to hh). The student will participate in developing algorithms for tau lepton identification, and will also be expected to play a role in the development of silicon module hardware for the ATLAS tracker Upgrade.

Contact: Dr Trevor Vickey (t.vickey@sheffield.ac.uk)

ATLAS: An inclusive search for Supersymmetry

The student will develop tools to test supersymmetry using multijet + missing ET decay signatures. The understanding of detector response will be crucial at the beginning of ATLAS operation to separate real physics effects from instrumental backgrounds. The student will also work on tracking reconstruction to enhance jet algorithms using an energy flow approach.

Contact: Professor Dan Tovey (d.r.tovey@sheffield.ac.uk) and Professor Davide Costanzo (d.costanzo@sheffield.ac.uk)

ATLAS: Search for supersymmetric partners of the bottom and top quarks

The student will develop an analysis to search for supersymmetric partners of the bottom- and top-quarks with ATLAS and will apply them to the latest data from the experiment. The project will focus on events where two b-quarks are reconstructed together with large missing transverse momentum. This channel offers the best possibility for discovering sbottom and stop squarks at the LHC, with stop squarks themselves expected to be significantly lighter, and hence more observable, than other strongly interacting SUSY particles. This project therefore offers the student the possibility of making a Nobel prize winning discovery!

Contact: Professor Davide Costanzo (d.costanzo@sheffield.ac.uk)

DRIFT and CYGNUS - Searches for Dark Matter Particles with Directionality

Sheffield is a key player in the world-leading dark matter experiment DRIFT that is seeking a unique directional signal for Weakly Interacting Massive Particles (WIMPs), the favoured candidate to explain the missing dark matter of the Universe. DRIFT is merging with multiple groups around the world to form a new collaboration, CYGNUS that aims to produce a network of directional detectors with capability eventually to reach below the so-called neutrino floor and to provide a definitive signal to prove that WIMPs exist in the galaxy. The thesis project will focus on development of new detector R&D using optical and gas charge readout technology for CYGNUS plus operation of the working DRIFT II experiments, including analysis to search for dark matter candidates and development of new techniques for track reconstruction. DRIFT is sited at the UK’s new deep underground laboratory at Boulby. Collaborating countries in CYGNUS include China, Australia, USA, Italy and Japan. For CYGNUS there will be opportunity participate in tests with new devices at Boulby and sites across these countries.

Contact: Professor Neil Spooner (n.spooner@sheffield.ac.uk)

Particle Detectors for Medicine using Liquid Argon

The Sheffield particle physics group is developing liquid argon technology for neutrino and dark matter particle physics. However, this technology can also be of use in medical nuclear physics, in particular for positron emission tomography (PET). This project will involve use of our dedicated liquid argon detector test facility at Sheffield to study new scintillation imaging gas photomultipliers and related charge and light readout technologies with a view to optimizing these for medical imaging applications including PET. The project will also involve development of GEANT4 and other detector simulations to back up the experimental work.

Contact: Professor Neil Spooner (n.spooner@sheffield.ac.uk)

Particle Detectors for Muon Tomography applied to Climate Change

The particle physics group at Sheffield is developing new uses for muon detector technology that has emerged from our work in dark matter and neutrino physics. The focus in this project will be on development of novel detectors for muon tomography to allow monitoring of CO2 stored deep underground. This is part of global efforts on carbon capture and sequestration (CCS) as a means to combat climate change. The project involves collaboration with geo-physics groups and development of new instruments to be installed and tested using the UK’s deep underground science laboratory at Boulby. The work will involve design, construction and operation of new muon tomography devices as well as simulations and data analysis for CCS.

Contact: Professor Neil Spooner (n.spooner@sheffield.ac.uk)

RATRACK - Directional Sensitive Nuclear Recoil Detectors for Homeland Security and Environmental Radon Assay

The Sheffield particle physics group is acknowledged by STFC as having one of the best programmes of spin-out activity designed for using particle physics technology in industry and for society. RATRACK is a novel gas-based particle detector spin-out technology with CCD cameras, developed from dark matter work, turned to allow 3D imaging of alpha particles and nuclear recoils induced by fast neutrons. The project involves design and optimization of a next generation device that can be used to do very sensitive measurements of environmental fast neutrons, including their direction, but also to allow assay of environmental radon or surface alpha contamination. The project involves international collaboration with groups in Italy, Australia and the US as well as links with industry.

Contact: Professor Neil Spooner (n.spooner@sheffield.ac.uk)

DUNE – Design and Optimisation of The Deep Underground Neutrino Experiment at Fermilab for Low Threshold Operation

DUNE is the a billion dollar international neutrino experiment in which a beam of neutrinos will be fired from Fermilab, USA to a 10 kton liquid argon detector built 1300 km away in a new underground facility at Homestake, S. Dakota. Construction has already begun but one issue to address is the ability of DUNE to detect low energy non-accelerator events, such as from possible proton decay or astrophysical neutrinos. The project will involve a combination of experimental work to measure and understand the critical low background performance of the DUNE detector components, specifically radon emanation and U/Th issues, plus simulations and analysis to assess the implications of this on the design and science capability for low energy physics. There will be chance for long term attachment (6-12 months) in Chicago at Fermilab. This a rare chance to become integral to work towards the huge DUNE experiment in the US, gaining both hardware and software expertise.

Contact: Professor Neil Spooner (n.spooner@sheffield.ac.uk)

ProtoDUNE – Test Experiment for the Deep Underground Neutrino Experiment DUNE - Optimisation and Data Analysis

ProtoDUNE is a 770 ton liquid argon detector being constructed at CERN as a test-bed for the huge DUNE experiment, a billion dollar international neutrino experiment in which a beam of neutrinos will be fired from Fermilab, USA to a 10 kton liquid argon detector in the Homestake mine, S. Dakota. This project will focus on optimization of the central Anode Plane Array (APA) detectors that are key to ProtoDUNE and are being built by Sheffield with other groups. The project involves finalising design of the APAs, developing simulations of the final detector and then analysis of particle beam data with a view to aiding the final design of DUNE itself. This includes study of electron lifetime performance and low energy performance. There will be opportunity for involvement in installation and operations of ProtoDUNE at CERN and a chance for long term attachment at CERN (6-12 months).

Contact: Professor Neil Spooner (n.spooner@sheffield.ac.uk)

SBND – Sterile Neutrino Search with the Short Baseline Neutrino Detector Experiment at Fermilab

The Short Baseline Neutrino Detector (SBND) at Fermilab is a 100 ton liquid argon detector that is part of a suite of three new detectors based on new technology using liquid argon, sited in a neutrino beam at Fermilab. Sheffield has played a leading role in construction of this new experiment, including contributing to design and construction of the main Anode Plane Arrays (APAs). SBND is due to start full operation in 2018/19. The project will focus on analysis of data in the area of searches for sterile neutrino events and the relationship to the dark matter problem. This includes development of LARSOFT simulations. There will be opportunity to contribute to final installation activities, detector optimization and operation. The project offers a rare chance in neutrino physics to gain experience of both detector hardware and operation as well as data analysis towards new physics. There will be chance for long term attachment (6-12 months) in Chicago, Fermilab.

Contact: Professor Neil Spooner (n.spooner@sheffield.ac.uk)

ARGONCUBE – Design, Construction and Test of the Liquid Argon Near Detector for the DUNE Neutrino Experiment

In association with the giant 10 kton DUNE (Deep Underground Neutrino Experiment) being built at Homestake there will need to be a smaller near detector at Fermilab. The Sheffield group is collaborating with Bern University to build and test a liquid argon version of this with responsibility to design, build and test a 1.0m x 0.5m time projection chamber device. The project involves contributing to the design, installation and operation of this with Bern colleagues and subsequent analysis of particle data following transfer to a test beam at CERN. There will be opportunity also to conduct support detector R&D using the Sheffield liquid argon test-stand facility to study upgrade options for the readout, including comparison of silicon photo-sensors, cryogenic photomultipliers, GEMs and micromegas devices. Critical measurements are anticipated of liquid argon parameters including electron drift. There will be chance of long term attachment (6-12 months) in Bern or at CERN in Switzerland.

Contact: Professor Neil Spooner (n.spooner@sheffield.ac.uk)

DM-ICE and COSINE-100 - Search for Dark Matter Annual Modulation

The Sheffield group is participating in the search for a galactic particle dark matter signals using the so-called annual modulation signal with the DM-ICE experiment 2.5 km below the South Pole and as part of the new COSINE-100 experiment on South Korea. Sheffield built the two NaI(Tl) scintillation detectors now running in the DM-ICE17 experiment. Recently DM-ICE has joined forces with groups across Asia to form the COSINE-100 that has just started operating 100kg of NaI. The project will focus on analysis of remaining data from the 17 kg prototype scintillator in the ice and new COSINE-100 data to search for a dark matter annual modulation signal. There will also be opportunity to contribute to design and test of the new crystals being developed for an upgrade to a 250 kg ultra-low background detector. Part of this work includes use of test facilities the UK’s Boulby underground site. There will be opportunity to participate in deployment activities in South Korea and possibly at the Antarctic South Pole.

Contact: Professor Neil Spooner (n.spooner@sheffield.ac.uk)

WATCHMAN – Nuclear Non-proliferation Detector Development

The Sheffield group is playing a leading part in a US-UK collaboration to establish a 1 kton neutrino detector based on water Cherenkov that can be used as a remote monitor of nuclear reactor operations. Such a device has unique capability to determine the reactor cycle and state of a remote reactor, of importance for possible nuclear non-proliferation applications. The student would be involved in simulations and detector development around research to optimise the sensitivity of such a device. This includes work to optimise the light collection and find a cost optimum for the expirement for the possibility fo installation in the UK’s deep underground science facility at Boulby, which is close to the Hartlepool civil reactor. This a unique project that combines fundamental neutrino physics with contributions to humanity through participation in nuclear non-proliferation activity designed to reduce the likelihood of nuclear material production for non-civil uses.

Contact: Professor Neil Spooner (n.spooner@sheffield.ac.uk)

Ionisation Cooling of Muons

A future Neutrino Factory or Muon Collider will use intense beams of stored muons. As muons are produced as tertiary particles (from the decay of pions which themselves come from a proton collision), they have to be “cooled” before injection into an accelerator. The short lifetime (~2 μs) means that novel cooling techniques are required. The international Muon Ionisation Cooling Experiment (MICE) is studying such techniques, and Sheffield has a leading role in the project. A PhD student working on MICE will gain experience of hardware and software development, taking part in a running UK-based experiment but attending meetings with collaborators around the world.

See the following webpages for more details:
MICE collaboration
Sheffield MICE

Contact: Dr Chris Booth (c.booth@sheffield.ac.uk)

Studying Neutrino Oscillations with the T2K Experiment

The Sheffield T2K group are currently involved in analyses of so-called CCpi0 events, i.e. charged current events that contain one neutral pion, an important channel when understanding electron neutrino appearance systematic errors. The group also has responsibility for timing calibration in the ND280 detector. The student will also have the opportunity to spend longer periods of time (typically 6-12 months) out at J-PARC where they will participate in shift work on the T2K ND280 near detector at J-PARC in Japan.

Contact: Professor Lee Thompson (l.thompson@sheffield.ac.uk)

Detector development for homeland security applications

The group has a long-standing track record of attracting grant income for applications of particle physics instrumentation in various areas. This studentship will be involved in consolidating existing work on developing methods and materials to augment and improve current techniques used in the border and mainland security. The PhD position will be largely experimental but some will involve some data analysis. There is the possibility of industrial placements during the period of study.

Contact: Professor Lee Thompson (l.thompson@sheffield.ac.uk)

Calibration of the HyperKamiokande neutrino detector

HyperKamiokande is a next-generation water Cerenkov neutrino detector that is planned to be built in Japan over the next 10 years. HyperK will play an important role in measuring the parameters in the PMNS neutrino mixing matrix and in determining whether or not we observe CP violation in the neutrino sector. A huge detector such as HyperK requires various calibration systems in order to fully understand aspects such as PMT characteristics and the properties of the water (scattering, absorption, etc.). The Sheffield group are involved in the design and testing of a calibration system based on the injection of short-duration light flashes from pulsed LEDs. This PhD will involve considerable experimental work, both at Sheffield and in Japan where a prototype calibration system will be deployed in the SuperKamiokande detector in 2018/19.

Contact: Professor Lee Thompson (l.thompson@sheffield.ac.uk)

WATCHMAN: an anti-neutrino detector for nuclear non-proliferation studies

The WATCHMAN project involves a joint US-UK collaboration of universities and national labs who are working to design and build an anti-neutrino detector deep underground that will monitor anti-neutrinos from nearby nuclear reactors. The ultimate goal of the project is to develop a tool that can be used in nuclear non-proliferation applications. This PhD will involve both computational and experimental work. The former will involve simulations of the sensitivity of the proposed detector and the assessment of the effect of backgrounds (e.g. cosmic-induced or natural radioactivity) to the performance of the detector. The expected time scale for the construction of WATCHMAN and the start of data-taking falls within the duration of this PhD (approximately 2019). Therefore, the experimental work will involve building, calibrating, and running the detector, as well as an analysis of the first reactor anti-neutrino data.

Contact: Professor Lee Thompson (l.thompson@sheffield.ac.uk) and Dr Matthew Malek (m.malek@sheffield.ac.uk)

Neutrino Oscillation Measurements with T2K

T2K is a long-baseline neutrino oscillation experiment based in Japan. The aims of the experiment are to improve the understanding of muon neutrino oscillation (to both electron neutrinos, 1-3 mixing, and tau neutrinos, 2-3 mixing) and to constrain the CP-violation parameter delta. The student will contribute to neutrino oscillation measurements either directly or by studying processes that contribute to the systematic error in the oscillation measurements. This project is likely to involve spending a significant amount of time (6-12 months) in Japan.

Contact: Dr Susan Cartwright (s.cartwright@sheffield.ac.uk)

Neutrino-Nucleus Interactions

A dominant cause of systematic errors in neutrino oscillation measurements is our current lack of a good description of the neutrino-nucleus cross-section. Building on past experience within the Sheffield T2K group, the student will work on improving the description of neutrino-nucleus interactions in the simulations used in T2K and other neutrino experiments. This will involve developing an understanding of the physical processes involved and how they are implemented in the simulations, and using data from T2K and other neutrino experiments to tune the models to improve their description of the data.

Contact: Dr Susan Cartwright (s.cartwright@sheffield.ac.uk)

Supernova Neutrinos in TITUS and Hyper-K

The Hyper-Kamiokande experiment is a proposed extremely large (Mton scale) water Cherenkov neutrino detector in Japan. Hyper-K will act as the far detector for a proposed next-generation neutrino oscillation experiment, but also has a strong research programme in non-accelerator neutrino physics. One area in which Hyper-K has good potential is the study of neutrinos from the next Galactic core-collapse supernova. The student will work on implementing the most up-to-date models of core-collapse supernovae in the Hyper-K simulation and investigating the sensitivity to the properties of both neutrinos and supernovae offered by the detection of a hypothetical supernova at a distance of order 10 kpc. (A real Galactic supernova cannot, unfortunately, be guaranteed on the timescale of a PhD studentship...)

Contact: Dr Susan Cartwright (s.cartwright@sheffield.ac.uk)

Gravitational Wave Searches with LIGO/GEO600/Virgo

The HEP group at Sheffield includes an active experimental gravitational wave research group, consisting of two faculty members, a postdoctoral researcher, and two current Ph.D. students. We are members of the LIGO scientific collaboration, and are active in detector commissioning, detector characterisation and data analysis in connection with the LIGO, Virgo, and GEO600 gravitational wave interferometers. In addition, we have a strong role in the GOTO dedicated gravitational-wave optical follow-up instrument, aiming at detecting optical counterparts to gravitational wave signals. Ph.D. projects in the group include gravitational wave data analysis, particularly fast real-time analysis pipelines and work with the electromagnetic follow-up group within LIGO, and the GOTO optical follow-up project. Advanced LIGO is due to come on-line for first science data in 2015, so this is an exciting time to be involved in gravitational wave interferometery.

Contact: Dr Ed Daw (e.daw@sheffield.ac.uk)

Dark Matter Search with the LZ Experiment

LUX-ZEPLIN (LZ) is a project to build and operate a high-sensitivity dark matter experiment in the deep mine at SURF (South Dakota, USA) able to probe most of the WIMP parameter space region free from astrophysical neutrino background. The PPPA group at the University of Sheffield is involved in the LZ experiment with a prime responsibility for developing software for modeling and data analysis, simulating background radiation and detection of various particles. The construction phase has been started in 2015 and it is a good time for a PhD student to be involved in the project.

The PhD project includes Monte Carlo modelling of the LZ experiment including its background and development of the analysis code in preparation for the data analysis. The student can also contribute to the detector construction and tests of different parts, as well as to the measurement of radioactive contaminations in different materials. There is an opportunity to spend 6 - 12 months in the USA and be involved in detector assembling and commissioning. The successful candidate should have a good knowledge of particle physics and programming skills. The knowledge of nuclear physics and particle astrophysics is desirable.

Contact: Dr Vitaly Kudryavtsev (v.kudryavtsev@sheffield.ac.uk)

Neutrino Oscillation Study and Proton Decay Search with DUNE

DUNE is a large international project to design, construct and operate a multi-kiloton scale liquid argon detector for neutrino physics, astrophysics and proton decay search. The detector will be built deep underground at the SURF facility (South Dakota, USA). The PPPA group is involved in the DUNE project with one of the responsibilities to model background events produced by cosmic-ray muons and investigating the sensitivity of the experiment to different tasks. This PhD project includes Monte Carlo simulations of muons and muon-induced cascades for different detector designs, studying discrimination between signal and background events and evaluating detector sensitivity. The student will also be expected to contribute to the data analysis and calibration of SBND (Short-Baseline Near Detector) to be installed at Fermilab in 2018 with a goal to test some neutrino oscillation anomalies reported by several experiments and search for sterile neutrinos. Another potential task within this PhD project is the calibration and analysis of data from ProtoDUNE - the small prototype of DUNE to be built at CERN in 2017. There is an opportunity to spend 6-12 months at Fermilab or at CERN working with the SBND or ProtoDUNE detectors. The candidate should have a good knowledge of particle physics and programming skills. The knowledge of nuclear physics and particle astrophysics is desirable.

Contact: Dr Vitaly Kudryavtsev (v.kudryavtsev@sheffield.ac.uk)

Cosmic-Ray Muons in Different Applications

Cosmic-ray muons are known to be useful in applications beyond particle astrophysics. They have helped to map structure of volcanoes and finding voids in various geological structures. Other possible applications include studies of geological repositories including monitoring carbon capture, tracing illicit nuclear materials etc. The PPPA group at the University of Sheffield, in collaboration with other institutions and industrial partners, pursues a wide programme related to these muon applications. This PhD project offers an opportunity for a student to apply the knowledge of particle/astroparticle physics and detector technology, in other areas which are linked to key problems of the contemporary world: atmospheric pollution, climate change, nuclear security etc.

Contact: Dr Vitaly Kudryavtsev (v.kudryavtsev@sheffield.ac.uk)

Detection of Contraband Explosives Using Neutron Activation

The Sheffield Pulsed Neutron Facility has been set up to assess cargo screening strategies based on neutron activation and induced fission. It is based on an inertial electrostatic confinement generator using deuterium-tritium fusion to produce pulses of 14MeV neutrons. This generator was manufactured by NSD-Fusion, now NSD-Gradel, Luxembourg. To date, the generator has been proven to operate reliably and many of its characteristics have been measured. Some of the possible cargo screening strategies have been demonstrated to work with simple single detector setups. In particular the thermal activation of nitrogen as an indicator of the presence of nitrogenous explosives is detectable with kilogram surrogate samples. We would like to extend this work by engineering an array of detectors capable of simultaneous measurement of gamma rays over a wide range of energies up to 12MeV. Additionally fast and thermal neutrons should be measured to assess neutron transparency and thermalization properties of sample cargoes. These detectors will be read out by a data acquisition system recording the energies and time-stamping hits over a time scale considerably longer than the thermalization time of the system. It is intended that the fusion of these data streams will allow considerably more exact characterization of potential threats than a single measurement would permit. Explosives will be identifiable by CHNO ratios, while fissile nuclear materials will be identifiable by die-away analysis which will distinguish delayed fissions.

Contact: Dr John McMillan (j.e.mcmillan@sheffield.ac.uk)

Testing Grand Unificiation: Do Protons Decay?

Grand Unified Theories (GUTs) postulate the merger of the strong force with the electroweak force at energies around 10^16 GeV. This is a trillion times greater than the center of mass energy at the Large Hadron Collider. Proton decay would provide evidence of GUTs, as the proton is stable within the Standard Model but permitted to decay in a Grand Unified context. The Hyper-Kamiokande experiment is a proposed megatonne water Cherenkov detector to be situated in Japan. Its extremely large volume makes it sensitive to proton decay; this sensitivity may be enhanced by a factor of ten if a small amount of gadolinium (0.1%) is added to identify the atmospheric neutrinos that can fake a proton decay signal. The ANNIE experiment at Fermilab will use Gd-loaded water to measure neutron multiplicity and pioneer this technique. The student will measure neutron yield in neutrino interactions at ANNIE, then use these results to model proton decay at a Gd-enhanced Hyper-Kamiokande. The project is likely to involve spending 6 - 12 months at Fermilab (Chicago) and short-term visits to Japan.

Contact: Dr Matthew Malek (m.malek@sheffield.ac.uk)

Why Are We Here? - Using Neutrinos to Understand the Matter / Anti-Matter Asymmetry

If we assume that the laws of physics are the same for matter and for anti-matter, then equal amounts of each should have been created in the Big Bang... and annihilated soon after. Clearly, this did not happen and our observations tell us that we live in a universe composed almost entirely of matter, with virtually no primordial anti-matter remaining. The reasons for this are not clear, but may be explained by violation of the 'charge-parity' (CP) symmetry for neutrinos. The first phase of the Tokai-to-Kamioka (T2K) experiment has seen initial hints of CP violation, which will be probed further during the second phase of operation (T2K-II) and with the proposed Hyper-Kamiokande experiment. T2K is a long-baseline neutrino oscillation experiment, located in Japan, which produces a beam of muon neutrinos. The neutrinos are measured with a multi-stage near detector after 280 meters of travel, and again with a 50,000 tonne water Cherenkov far detector after 300 km. Simulations have shown that our potential for discovering CP violation can be greatly improved by constructing an intermediate-distance kilotonne-scale water Cherenkov detector. Such a detector has been proposed and it is expected to be constructed within the time-scale of this PhD position. This is an experimental PhD with significant components of simulation and data analysis. The student will travel to Japan to participate in the construction and commissioning of the new detector. Once the detector is completed, the student will collect and analyse data within the context of the T2K-II search for CP violation, as well as simulating its effect on the sensitivity for the future Hyper-Kamiokande experiment.

Contact: Dr Matthew Malek (m.malek@sheffield.ac.uk)

Light Sterile Neutrinos: Reality or an Experimental Error?

In recent decades, a variety of experiments have measured anomalies that may be indications of a fourth neutrino flavour. In contrast to the three known 'active' neutrinos, this fourth flavour would be 'sterile', with no couplings via weak interactions. The mass square difference between the active flavours and the sterile neutrino, measured from these anomalies, is approximately 1 eV^2, which is greater than the mass square difference amongst the three active neutrinos. There is no a priori theoretical motivation for sterile neutrinos to exist at this mass. Thus, if these experiments are correct, the existence of a sterile neutrino would be exciting physics beyond the Standard Model. However, it is worth nothing that all of the experiments to see indications of this phenomenon are single detectors acting alone. Therefore, it is also possible that the various anomalies may be explained via uncertainties in the neutrino flux or nuclear effects. To properly confirm (or refute) the existence of a light sterile neutrino, it is necessary to construct an experiment with near and far detectors; a comparison of measurements would cancel such uncertainties. The Short-Baseline Near Detector (SBND) is part of the Fermilab Short Baseline Neutrino (SBN) programme, which will use three experiments to make such a comparison. One of the experiments, MicroBooNE, has already started operation; SBND is expected to commence data taking in 2019. The student would have the opportunity to participate in detector construction and to participate in the existing Sheffield efforts on SBND analysis. In collaboration with the MicroBooNE and ICARUS experiment, this PhD position will culminate in a search for evidence of sterile neutrinos. The project offers the possibility of a long-term attachment (6 - 24 months) at Fermilab, near Chicago.

Contact: Dr Matthew Malek (m.malek@sheffield.ac.uk)


Materials physics

The materials physics group conducts research (both experimental and theoretical) into the physics and applications of polymers, organic-semiconductors, functional nano-particles, biological materials, imaging and instrumentation.

For general enquiries contact: Professor David Lidzeyd.g.lidzey@sheffield.ac.uk

Find out more about soft matter physics research

Ultrafast singlet exciton fission in carotenoids

In solar cells, the ability to absorb one photon and harvest two electrons can lead to internal quantum efficiencies of up to 200%. This is possible using organic semiconductors via a process known as 'singlet exciton fission' (SEF), where the primary excited state (singlet exciton) can split into two distinct triplet excitons which can both be harvested.

SEF has also been shown to occur in naturally occurring carotenoids such as astaxanthin and zeaxanthin, but we have recently demonstrated that current theory does not adequately describe SEF in these systems.

The proposed project will involve using time-resolved ultrafast spectroscopy in Sheffield's new laser facility to study SEF in carotenoids. The main outcomes of the project will be two-fold:
  1. to develop a new description of this SEF process in collaboration with theoreticians, enabling future design of efficient SEF materials for solar cell applications.
  2. to determine whether SEF in carotenoids has a biological role.

Contact: Dr Jenny Clark (jenny.clark@sheffield.ac.uk)

Ultrafast spectroscopy of single crystal organic semiconductors

Organic semiconductors are exciting materials. They are not only starting to compete with traditional (opto)electronic materials in device applications, they are also intrinsically sustainable. Solution-processed organic photovoltaics, for example, use ~10 times less energy to produce than any other PV technology and are only made from earth-abundant elements.

Until recently, it was thought that the problem with organic semiconductors was disorder, thought to be a fundamental draw-back of solution-based (i.e. sustainable, low-cost) deposition techniques. Work in the last 4 years has changed this paradigm. Solution-processed highly ordered single crystals now demonstrate field-effect mobilites above 10cm2/Vs. Only 10 years ago such ultra-high mobilities at room temperature in thin organic films would have been considered unachievable by many experts in the field.

These new ultra-high mobility thin films pose a considerable challenge to our understanding of charge and energy transport. They operate in what is known as the 'intermediate coupling' regime where energy and charge transfer can be described as being somewhere between the band-like transfer that occurs in highly ordered inorganic semiconductors and the purely hopping transfer that occurs in very disordered systems.

In this project, you will measure materials from collaborators in Japan using Sheffield's new laser facility to attempt to describe the energy transport and radiative and non-radiative deactivation in the intermediate coupling regime. It is expected that you will collaborate with theoreticians in the USA to develop models to interpret the data.

Contact: Dr Jenny Clark (jenny.clark@sheffield.ac.uk)

Development of spray-coated perovskite solar cells

The last few years has seen tremendous progress in the development of photovoltaics devices based on perovskite materials. Such materials can be processed from solution into thin-films, offering the prospect of manufacturing efficient photovoltaic-devices over large areas using comparatively cheap materials and processes, in which the amount of embodied energy (and carbon) is substantially reduced. This PhD project will develop a range of new perovskite precursor 'ink' formulations, and will then explore their deposition over large areas using and ultra-sonic spray-coating. This technique offers the prospect of device fabrication at low cost over very large areas and are of significant interest in real-world manufacture processes. A central task will be to develop a toolbox of materials and spray-coating process techniques that can be applied to curved surfaces. The key science challenge to be addressed is to open a sufficiently wide process-window permitting a surface having some degree of surface-roughness to be used as the substrate for a perovskite solar cell. We will develop many of the necessary spray-casting methodologies and materials by initially working on flat metal-oxide coated glass. This will build upon our recent success where we have fabricated fully spray-cast standard architecture and inverted architecture perovskite devices having a PCE of 10%. The student will be tasked with the development of new spray-coating recipes to deposit caesium-containing perovskite materials, with the objective of reaching a PCE in excess of 15%. Once basic techniques have been established, the student will move onto spray-casting over curved substrates that will be formed from carbon-fibre composites. Here, the curved substrates will be fabricated by collaborators in the Department of Mechanical Engineering at the University of Sheffield. The research will also involve the use of a number of techniques to explore device operation, efficiency, homogeneity and yield. This is an experimental research project suitable for Physicists, Material Scientists, Electronic Engineers or Physical Chemists having good, hands-on practical skills who is interested in the development of new technologies.

Contact: Professor David Lidzey (d.g.lidzey@sheffield.ac.uk)

Polariton lasing in organic semiconductor microcavities

The absorption and emission of light is fundamental to both optoelectronics and biological processes. This process usually takes place in discreet jumps, in which an excited state electron emits a photon as it returns to its ground state, or a photon is absorbed to create an excited state electron. Our growing ability to manipulate light and matter however now allows a different possibility, in which the photon and exciton are ‘mixed’ together, forming a type of state called a cavity-polariton. Rather than being of simple academic interest, cavity polaritons are a fascinating test-bed for fundamental physics and can have potential applications in ultra-low threshold lasers, on-chip communications elements and new types of quantum-mechanical simulator devices.

Polaritons can be created in an optical structure in which a semiconductor is placed between two highly reflective mirrors. This structure traps photons into a series of discreet optical modes. Within the so-called ‘strong-coupling regime’ the photons trapped in the cavity can couple with the excited states of a semiconductor within the cavity and form the cavity-polaritons. In this project, you will develop strong-coupled optical cavities that contain a range of organic semiconductor thin films and assess their relative lasing threshold when optically pumped. You will explore a wide range of materials, including organic semiconductor dyes and perovskite nanocrystals with your objective being the fabrication of polariton lasers that operate at very low thresholds. You will also develop nanoscale lithographic techniques to laterally pattern the cavity structures, forming optical micro- pillars, which you will explore with high-resolution microscopy techniques. As part of the project, you will collaborate with our colleagues at the Universities of Southampton and St. Andrews as part of a multi-million pound ‘Hybrid Polaritonics’. This is an experimental research project suitable for Physicists, Electronic Engineers or Physical Chemists who wish to build a career in the field of photonics and optoelectronics.

Contact: Professor David Lidzey (d.g.lidzey@sheffield.ac.uk)

Surface waves on thin polymer films

Recent work undertaken within the department of Physics and Astronomy at the University of Sheffield suggests that, when a thin film of a glassy polymer undergoes a phase transition there exists a highly motile layer at the surface. However there is still significant debate within the research community as to whether this ultrathin layer exists.

A PhD student working on this project will use a combination of experimental techniques, including ellipsometry, atomic force microscopy and phase contrast microscopy, to further our understanding of this thermodynamic process. Alongside this the student will work alongside theorists within the group to develop a model to describe the phase transition process of different thin polymer films.

Contact: Dr Matt Mears (m.mears@sheffield.ac.uk)


Physics education

Deep vs rote learning of physics in Higher Education

The idealistic aim of teachers in Higher Education institutions is for all graduates to develop a deep understanding of their subject and skill-sets, and yet the modular structure and emphasis on equation-based assessments mean physics students are (unintentionally) encouraged to only learn what is necessary to pass the exam.

A PhD student working on this longitudinal project will first examine the types of learning styles within physics courses at higher education institutions and to assess their effectiveness in learning both skills and core knowledge. In subsequent work they will develop interventions to improve the different learning styles and measure the impact their designed interventions have made. The student will be expected to work with collaborators in different departments with the University of Sheffield and from different institutions within the UK.

Contact: Dr Matt Mears (m.mears@sheffield.ac.uk)