PhD projects

We're recruiting PhD students to work on the following projects. We encourage you to do some research on our academics to really get to know how their work and expertise fits with your interests before you apply.

If you wish to learn more about a particular academic's research or discuss a project you have in mind, they are happy to answer specific questions by email or telephone.

 We have many exciting PhD projects on offer within our four research groups. A selection are given here, new opportunities come up all the time so please do get in touch:

* Funding already secured 

Physics of Life - Biological Physics and Biophysics 

Below are specific projects but we always welcome new proposals for research projects. Please contact the research group if you have something else in mind. 

3D Genomics for a better synthetic biology and gene therapy.

  • Supervisor Dr Agnes Noy and Mark Leake
  • Funding Self-funded students only
  • Application deadline 1st September 2019

While genome sequencing has led to significant increases in the amount of genetic information available, we are still far from a comprehensive understanding of how genomes work. Recent experiments have shown that DNA looping and folding are essential mechanisms in the switching of genes between their on and off states [1]. This has led to the idea that genetic information is also encoded through DNA topology and highlights the importance of studying the physical properties of DNA [2-4]. This project aims to predict DNA topology for improving genetic devices and genomes for utilisation in synthetic biology and gene therapy. Theoretical predictions will be compared with experiments done at the group of Mark Leake. Your project will allow you to:

1) Describe DNA loops with a physics-based computational methdology. Small loops are good models for understanding the essentials of gene regulation and also they are excellent gene-therapy vectors for introducing external genetic material in our cells. You will learn the most advanced techniques on molecular modelling

2) Develop a software for structural prediction at the genomic scale. The details learnt from small loops will be used for predicting the 3D architecture of genomes and improved them in the field of synthetic biology or biology engineering, absolutely critical for the production of biofuels, drugs or food additives. You will be trained in data analysis and bioinformatics as well as be familiar on the fields of biotechnology and synthetic biology.

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Developing next-generation technology touching life physics tools to tackle debilitating infections and cancers

Our knowledge of many debilitating human diseases is limited by technology: conventional approaches fail to render the quantitative details needed to address key mechanistic questions. This project will develop new biophysics tools for molecular observation in live cells to aid understanding of two diseases of high biomedical importance - (i) Determining roles of a key haematopoietic cytokine receptor, MPL, which interacts with ‘oncogenes’ in rare blood cancers; (ii) Investigating the assembly/disruption of a druggable unique protein structure in protozoan parasites that causes sleeping sickness in humans:

1. Develop new microfluidics for high-throughput immobilization and optical imaging of cells, facilitating rapid exchange of cell microenvironments, screening of cell types/states and other biophysics investigations including genetics profiling.

2. Design and construct optical instrumentation to enable rapid tracking of labelled proteins in cells to nanoscale precision in 3D and improve the time scale of sampling to sub-millisecond levels to probe rapid molecular conformational dynamics.

3. Develop optical tools to determine cell physiology using novel probes for ratiometric imaging and Förster resonance energy transfer (FRET) to quantify precise pH, ionic strength, membrane voltage, viscosity, and molecular crowding.

4. Develop new computational methods of machine learning/AI, principal component analysis and Hidden Markov Modelling.

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Dissecting cell complexity using super-resolution microscopy, one molecule at a time

The stress response of sporulation in bacteria is a fantastically system for studying biophysics processes of emergent complexity. This project involves high resolution bioimaging studies in living bacteria of proteins involved in sporulation.

You will study sporulation as a model system to understand how structural and functional complexity emerges in living cells. We aim to understand the: (i) structure and function of proteins involves in regulating sporulation and forming channels between the spore and the mother cell; (ii) roles of the cell wall remodelling during spore formation engulfment. You will use, and develop, pioneering imaging approaches of in the Leake group enabling you to monitor spatiotemporal dynamics, kinetics and interactions of these processes in functional, living cells in real time, one molecule at a time.

This is particularly timely since we have acquired compelling preliminary single-molecule data from several new functional B. subtilis bacterial strains with significant progress in the required molecular biology underway: it is an ideal time to capitalize on these developments by performing extensive functional imaging and analysis combined with complementary new biochemical and genetics investigations.  

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Single-molecule imaging in live cell to study gene geography and the role of DNA biophysics in regulating genes

Your project will address the key question of what is the importance of the physical location of genes in determining their state of activity. We will aim to address this question by studying the effects of bacterial chromosomal gene order on spatiotemporal expression in the context of folded, native genomes. You will use single-molecule bioimaging and computational analysis to determine the output from genes are their location is changed, and how this is affect to whether or not the cell is stressed. This will give a unique insight into how the very local state of DNA topology affects whether or not genes in live cells are switched on or off. Specifically:

1. You will characterize the spatiotemporal localization of new E. coli bacterial strains which expressing genomic fusions to a key enzyme DNA gyrase which relieves DNA torsional stress. These are constructed to use a nucleoid associated protein Fis as a marker for DNA supercoiling inside each cell.

2. You will use super-resolution millisecond Slimfield microscopy which is sensitive at a level of single-molecule detection to determinate the dynamic pattern of spatial localization and stoichiometry of these gyrase subunit proteins GyrA and GyrB to nanoscale precision in single live E. coli cells.

3. You will help to construct under expert teaching several dual-colour fluorescent protein fusion constructs integrated into the E. coli genetic code to pairs of DNA gyrase subunits, and also to Fis, and to a range of different established genome loci markers.

4. You will use nanoscale co-localization microscopy, real-time FRET, and FRAP/FLIP to determine the dynamic moelcular interactions, kinetics and molecular turnover of gyrase components in live cells under a range of bengin and stressed conditions including the appliation of gyrase targetting antibiotics.

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The Calcium: where molecular modeling meets nano-scale microscopy

Calcium is an essential ion for the condensation of biomolecules and for the formation of materials in living organism like bones and teeth. It also estabilizes a DNA mesh present on bacterial biofilm with the function to make bacteria resilient against antibiotic. Despite this enormous impact, the initial steps of calcium-molecule interaction and their impact on the nucleation of biominerals are not well understood. On this project we will describe the first stages of the interaction between Ca2+ and the protein osteopontin (OPN), which has been identified as a key protein regulating the growth of bone mineral. Further, the role of Ca2+ in the organisation of DNA will be investigated. Theoretical predictions will be compared with experiments done at the group of Roland Kroger  at the York JEOL Nanocentre. Your project will allow you to:

1) Describe DNA/Osteopontin folding caused by Ca2+ with molecular modelling. This is relevant for tackling the challenge of antibiotic resistence and for the field of bone regeneration. You will learn the most advanced techniques on molecular modelling

2) Detailed description of Ca2+ interaction using QM-based methodologies. A refinement of the interaction will be obtained by DFT with the leading software CASTEP/ONETEP in collaboration with Matt Probert, who is one of the main developers of the code.

 

Apply now

The long and winding roads of the cell

Intracellular membrane trafficking is essential for many cellular processes and its impairment leads to over 80 major human diseases. Elaborating our understanding of the molecular mechanisms regulating membrane trafficking will be invaluable for developing future strategies to tackle trafficking related pathophysiologies, resulting in improving the quality of life for those afflicted. We seek to address fundamental, open questions in membrane trafficking by assembling a highly interdisciplinary research team to integrate biochemical, genetic and cutting-edge biophysics tools.

Your project will allow you to:

1. Determine spatial localization patterns for recycling. To test the hypothesis that cargo trafficking occurs via two distinct surface recycling routes we will map the patterns of dynamic spatial localization of the endolysosomal system and recycling cargoes in live yeast.

2. Characterize transcriptional/metabolic control of recycling. We will use glucose depletion as a stress factor to study the interplay between transcriptional and metabolic control of recycling, testing hypotheses that transcriptional upregulation of endocytosis is mediated through the Mig1 repressor, and inhibition of surface recycling is initiated by novel factors we have identified.

3. Determine factors driving endosomal protein sorting. We predict surface recycling depends on the physical separation of endosomal proteins from maturing endosomes, and will test how the local intracellular

Apply now

Condensed Matter Physics 

Below are specific projects but we always welcome new proposals for research projects. Please contact the research group if you have something else in mind. 

Atomistic simulations of advanced permanent magnet materials

  • Supervisor Dr Richard Evans
  • Funding Self-funded students only
  • Application deadline 1st September 2019

Neodymium permanent magnets are ubiquitous in technologies from cars to wind generators due to their inherent efficiency in converting electrical power to mechanical motion or vice versa. Next generation rare-earth-transition metal permanent magnet materials based on the TmMn12 (RETM12) structure present an exciting opportunity to double the energy efficiency of the materials. Coupled with new motor designs this presents the possibility of doubling the power output of a wind turbine or range of hybrid car with the same battery size.

The aim of this funded PhD project is to develop new atomistic models of RETM12-based permanent magnet materials to predict their performance and understand the fundamental magnetic properties. These models will be used to guide industrial magnet production in collaboration with Toyota Motor Corporation and the MagHEM project to accelerate the development of next generation magnets with ultrahigh energy efficiency. 

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EBIC environmental STEM microscopy for energy materials and gas sensors

Electron Beam induced current (EBIC) is an electron probe technique widely used in the semiconductor industry for the analysis of p-n junctions, minority carrier distributions, and material defects. It has been developed for the SEM environment with the spatial resolution limited to tens of nanometres. Aberration corrected STEM (scanning transmission electron microscopy) is able to provide atomic scale resolution but cannot benefit from commercially available EBIC packages.

This project goal is to develop EBIC analyses techniques for STEM microscopy allowing to studying material defects and electric properties of thin films down to the atomic scale. This development combined with the unique capabilities of the double aberration corrected gas environmental STEM in York, will open the path for the fundamental study of the electric properties in nanomaterials during gas environment exposure as well as the effect of electric bias on phase transformation as such as oxidation and reduction.

This technique once developed will be applied to materials for solar cell structures and gas sensing devices.

Apply now

First principles modelling of defects in solar absorber materials

  • Supervisor Dr Keith McKenna
  • Funding Self-funded students only
  • Application deadline 1st September 2019

A number of materials are emerging as promising candidates to replace silicon in the next generation of solar cells. They offer the prospect of high efficiency, low cost and flexibility allowing for their incorporation into building materials for example. It is critical to understand the properties of atomic scale defects in these materials (such as vacancies, dislocations and grain boundaries) which can negatively impact both performance and stability.

The project will involve the application of density functional theory (DFT) to investigate the properties of a range of defects in solar absorbers such as CdTe, CH3NH3PbI3 and Cu2ZnSn(S,Se)4 in order to understand how to optimise materials for applications. You will work closely with experimental collaborators to test and verify your predictions.

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Iron Oxidation at the atomic scale: an In-situ environmental TEM/STEM study

Fe and Fe-oxide (FeOx) based nanoparticles (NPs) have shown promising applications in physical and medical sciences. These include magnetic storage devices, catalysis, contrast enhancement in magnetic resonance imaging and magnetic hyperthermia. These applications rely on the magnetic and catalytic properties of the NPs. In particular, the NP magnetic properties are strongly influenced by their stoichiometry and their crystalline structure. Understanding the Fe oxidation processes down to atomic scale is paramount for the control of NPs production. It has been previously shown that crystalline defects in magnetite (Fe3O4) thin films are detrimental for their overall magnetization. In our previous work on such films, we have shown that ex-situ annealing under a CO/CO2 gas mixture can successfully produce Fe3O4 thin film virtually defect free with bulk like magnetic properties. In the first phase of this project we will expand the gas capability of the York Environmental Scanning Transmission Electron Microscope (ESTEM) by implementing a CO/CO2 gas line that will add up to the existing O2, N2 and H2 ones. In the second phase the Fe-O phase diagram will be investigated in-situ for nanoparticles and thin films from room temperature to 1100C. The phase transformations between Fe-oxides phases and their stability will be explored at the atomic scale. In particular to understand the optimal conditions to produce single crystal, defect free and chemically ordered magnetite nanocrystal with improved magnetic properties. This research will provide a deeper insight in the oxidation mechanism, crystalline defect formation, and their relation to the magnetic properties to great advantage to the field of magnetism and catalysis with potential industrial applications.

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Light emitting two-dimensional materials for silicon emitters*

  • Supervisor Dr Yue Wang & Professor Thomas Krauss
  • Funding The three-year studentship provides a yearly stipend (£14,777 for 2018-2019). The studentship also covers fees for UK/EU students.
  • Application deadline 1st September 2019

Silicon photonics has been widely recognized as the potential technology to achieve broadband, high-density, high-speed data interconnections for next generation computing. The progress achieved in recent years in this field has been very exciting. However, an on-chip silicon light source at low-cost still remains challenging, as silicon itself does not emit light efficiently. Two-dimensional (2D) materials that were spawned out of the graphene revolution can address this challenge. This family of materials exhibit remarkable properties, including excellent electrical conduction and efficient light emission.

The aim of this project is to develop silicon light-emitting diodes (LEDs) and lasers by integrating 2D materials with silicon nanocavities. The student will work alongside research assistants, and UK and international collaborators to examine the light-emitting properties of suitable 2D materials that are both optically and electrically pumped. The student will also be involved in the design of passive and active devices using computer modelling, fabrication and characterisation of devices in our state-of-the-art clean room and optics laboratories.

We are looking for an enthusiastic candidate with a background in photonics, electronics, physics or material science to take on this project. The PhD studentship will be undertaken within the Department of Physics at the University of York, starting before October 2019. The three-year studentship provides a yearly stipend (£14,777 for 2018-2019). The studentship also covers fees for UK students. Informal inquiries can be made to Dr Y Wang (yue.wang@york.ac.uk) with a copy of your curriculum vitae and a cover letter.

 

Apply now

Modelling the properties of electron and hole polarons in materials

  • Supervisor Dr Keith McKenna
  • Funding Self-funded students only
  • Application deadline 1st September 2019

The strong coupling between electrons and phonons in some materials leads to the formation of small polarons (quasiparticles comprised of a localised electron and an associated polarisation field). Predicting the properties of polarons is an important fundamental problem as well as being relevant for technologically important phenomena such as magnetism, photoconductivity, dielectric response and reactivity.

In this project you will employ first principles methods recently developed in our group to predict the formation and properties in a range of previously unexplored materials including oxides, nitrides and perovskites. These predictions will be tested in close collaboration with experimental collaborators.

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Nanophononic metamaterials: engineering phonons to convert between heat and electricity

  • Supervisor Dr Phil Hasnip
  • Funding Self-funded students only
  • Application deadline 1st September 2019

Thermoelectrics are materials which convert temperature gradients into electricity, or vice versa. These materials can harvest waste heat from industrial processes, turning it into electricity, or use current to provide efficient cooling. These require a material with high electrical conductivity and low thermal conductivity. For metals these are contradictory, since both current and heat are carried by electrons; however, in semiconductors the heat is carried by phonons. Previous semiconductor research has focused on introducing defects to scatter heat-carrying phonons, but electrons often scatter from these too, lowering the electrical conductivity.

We propose a novel approach, using nanoscale engineering to tailor a material’s phonons. By patterning the material’s surface, specific phonon modes may be created which hybridise with heat-carrying phonons in the bulk material, reducing the thermal conductivity 100-fold. The bulk material is completely unchanged, so electrical properties are unaffected. This new class of nanostructures is known as nanophononic metamaterials (NPMs), and have the potential to have higher thermoelectric figures of merit than any previously known material.

Fabricating these nanostructures is challenging, and it is vital to focus on specific NPMs which can deliver the phononic and electronic properties required for high-efficiency thermoelectrics. We propose to use state-of-the-art quantum mechanical simulations (DFT) to predict and model the electronic and phononic properties of NPMs and, coupled with larger semi-empirical models, to design realistic nanoscale device NPMs with high thermoelectric efficiency. These designs will form the basis for new collaborations with world-leading experimental groups, in order to fabricate the NPMs and verify their performance.

This work will be carried out in collaboration with Dr Mahmoud Hussein (University of Colorado Boulder, USA).

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Theory-led optimisation of materials for tunnelling magnetoresistive devices

  • Supervisor Dr Keith McKenna
  • Funding Awaiting funding decision
  • Application deadline 1st September 2019

Tunnelling magnetoresistive devices find applications as a magnetic sensors in hard disk read heads and in emerging non-volatile magnetic random access memory (MRAM) technologies. The active part of the device consists of an insulating MgO film sandwiched between two ferromagnetic electrodes. While great progress has been made in the performance of these devices there is a need to make further improvements in the materials to allow widespread adoption of MRAM technology for memory applications. This includes finding new barrier materials which present a lower resistance-area product and understanding and mitigating the negative impact of defects such as vacancies and grain boundaries on performance.

In this project you will employ first principles methods (density functional theory) to model materials for tunnelling magnetoresistive devices in order to guide the optimisation of this technology. You will work closely with experimental collaborators to test and verify your predictions.

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Topological insulator based thermoelectrics

 

Scope and novelty Thermoelectric (TE) devices convert heat into electricity and represent an important route for green technologies. They have the potential for making an impact in many fields, such as portable devices (medical applications) and smart grid systems (coupled with batteries and photovoltaics). The quality of TE materials is defined by the dimensionless figure of merit ZT= (S2σ/κ)T, where S is the Seebeck coefficient,  σ theelectrical conductivity and κ the thermal conductivity; with larger values of ZT  corresponding to higher energy conversion efficiency. The two main parameters are proportional to each other, i.e. increasing the electrical conductivity results in increase of thermal conductivity. Hence it is a main challenge in the field of thermoelectrics to increase the electrical conductivity and to keep the low thermal conductivity.

 

Scope of the proposed PhD project is the use of 3D Topological Insulators (TIs) as TEs.  The special topology of these surface states means that there is no dissipation from electrical conduction through these channels whilst an increased number of both extended and point defects can drastically decrease the thermal conductivity. Hence these materials have the potential for the highest thermoelectric figure of merit of any material!

 

In particular, this project will explore the role of their dissipation-less surfaces and topologically protected states at structural defects, with respect to their electronic and thermal transport properties.

 

The project will involve the Tis growth at the Department of Physics at York, structural and electronic structure characterization with state of the art electron microscopy at the York-JEOL Nanocentre and SuperSTEM facilities and thermoelectric transport property measurements at the University of Manchester.

 

This project will be great opportunity to demonstrate how fundamental research translates into real world solutions.

 

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Toward next generation of solar cells: the correlation between efficiency and interface atomic structures in perovskite solar cells*

  • Supervisor Dr Vlado Lazarov and Leonardo Lari
  • Funding Fully funded position available. Open to Home/EU students only
  • Application deadline 1st September 2019 or until a suitable candidate is found. 
  •  Start date October 2019 

Perovskite solar cells (PSCs) have the potential to revolutionise the field of solar cells. Their efficiency in the last decades has increased by an order of magnitude, which is unprecedented in this field. In addition, they are cheap to be made and easy to manufacture. Hence the tremendous interest in perovskite solar cells as the next generation of efficient and cost effective solar cells. Further efficiency enhancement, improving their stability as well as making them environmentally friendly requires: i) the fundamental understanding of the interfaces between the TiO2 and the perovskite layer and ii) the developing of a Pb-free perovskite absorber layer. This project aims to address these two outstanding challenges by atomic level characterisation and quantum mechanical modelling using density functional theory (DFT).

Very recently, GreatCell Solar has shown that halide treatments of TiO2 nanopowders, used as electrode material in perovskite cells, further boost the perovskite solar cells efficiency. However, this important empirical finding is limited due to the lack of the understanding of the mechanism of improved efficiency. The first goal of the project is to understand how the structure and chemistry of the TiO2 electrode and its interface with the perovskite layer affects the efficiency of the solar cells. This will be done by employing state of the art atomic resolution imaging and spectroscopy coupled with quantum mechanical calculations. Achieving of this goal will enable developing a new doping strategy for more efficient cells. The second goal of the project is to develop a new absorber perovskite layer that is Pb-free, which will lead to environmentally friendly perovskite solar cells. This project will be conducted jointly with GreatCell Solar, the UK leader in perovskite solar cells research.

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Towards measuring the magnetic field of single atoms: EMCD in electron microscope

The desire for investigation tools with the ability of detecting very localized magnetic properties down to atomic scale is driven by the need of drive of developing ultrafast, low power and non-volatile data and logic devices.  

Electron magnetic circular dichroism (EMCD) in an electron microscope, is a method with the potential to reach the ultimate goal of detecting magnetic property of a single atom. This capability would allow understanding the magnetism of nanostructures which includes nanoparticles, artificial heterostructures for logic and data storage, as well as answering some of the fundamental questions in magnetism and spintronics.

This project aims to establish the experimental methodology for atomic scale EMCD measurements in a state of the art Scanning Transmission Electron Microscope and apply those to investigate the magnetic properties of selected material structures. As most of EMCD studies suffer from low magnetic signal to noise ratios and thus even in optimized experimental conditions data collection can be challenging, part of the proposed project will be the development of advanced data-processing methods for atomic resolution EMCD extraction.

The experiments will take part on the state of the art microscopes at the UK national facility for electron microscopy (SuperSTEM) at Daresbury. The project is in collaboration with Dr. Jan Rusz, Upsala University, Sweden.

Advisors: Dr Demie Kepaptsoglou and Dr Vlado Lazarov.

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Nuclear Physics 

Below are specific projects but we always welcome new proposals for research projects. Please contact the research group if you have something else in mind. 

Discovering Exotics at Jefferson Lab*

  • Supervisor Dr Mikhail Bashkanov
  • Funding Fully funded project for Home/EU students only
  • Application deadline Until a suitable candidate is found

The Hadron and Nuclear Physics group at the University of York is looking for a bright and enthusiastic PhD student to discover exotic particles at Jefferson Laboratory utilizing intense electron beam and CLAS detector.

The fundamental theory thought to describe the strong interaction is Quantum Chromodynamics (QCD). QCD permits a large variety of bound states of quarks. The simplest and best-established configurations are mesons (quark-anti-quark systems) and baryons (3 quark systems). The field is currently undergoing rapid change with claims of tetraquarks, pentaquarks, hexaquarks and hadronic molecules only recently starting to reveal themselves. The advance has been made possible through exploiting cutting-edge particle beams at the frontiers of intensity, coupled for the first time with large acceptance particle detectors. The field has attracted very significant public interest and has high scientific impact. Stories about discoveries of new exotic particles attract significant media attention.

Our group is leading exciting studies which are revealing six-quark states – hexaquarks [PRL 1,2,3,4]. We exploit the uniquely clean and controlled production environment accessible through photo- and electro-induced reactions. Proving the exotic nature of a new particle is a challenging task for the majority of the cases. However hexaquarks, where baryon number B=2 are easily identifiable. Our group was involved in a recent discovery of a first non-trivial hexaquark, the , having quark content uuuddd. A large fraction of our current activities are now devoted to this discovery: we have recently shown that the  may form copiously within neutron stars influencing fundamental properties [PLB] and also be produced significantly in early Universe.

Like any other particles, the  does not appear alone, but as a part of an SU(3) multiplet. In the ’s case it is antidecuplet, so we expect 9 more particles with the same spin-parity ( ) but different strangeness to be discovered. The next candidate for the discovery would be  – a particle with a quark content . This particle can be produced in large quantities at the JLab facility and detected by the high acceptance CLAS12 detector apparatus. After the energy and the luminosity upgrade of the JLab one can collect adequate statistics within few weeks of data taking. The first CLAS beam time with a deuteron target has been just started. For a PhD student it would be a golden opportunity to start the project with the data taking and complete it with an important discovery paper.

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Fission studies of neutron-rich nuclei*

Project Description

The RIBF facility at RIKEN in Tokyo, Japan is the world’s leading laboratory in the production and study of the most exotic nuclear systems that we can currently access. The SAMURAI setup in particular is built around a large-acceptance superconducting magnet and exploits nuclear reactions of heavy-ions to probe new quantum phenomena and shed light on unexplored areas of stellar nucleosynthesis. In this PhD project you will optimise and utilise a pioneering method to study the fission of exotic nuclei. Fission properties in these systems will be studied for the first time, advancing our current understanding of r-process recycling. This new investigation on fission of exotic nuclei marks a new generation of experiments in the field. As part of this PhD project, you will spend a substantial amount of time at RIKEN, Japan, where you will participate in the design and setup of the experiment, configure state-of-the-art radiation detectors and utilise large-scale data analysis methods. The experience, skills and networking obtained through this PhD will be a valuable asset for pursuing a career in academia or industry.

The Nuclear Physics group at York

In the nuclear physics group at York, we focus on carrying out world-leading research aimed at the study of the fundamental properties of atomic nuclei and the origin of elements in the cosmos, employing and developing state-of-the-art experimental and theoretical techniques. As well as pursuing fundamental research focusing on key questions at the forefront of the field, we work to develop new techniques in nuclear technology, working closely with industrial partners. We are also strongly committed to our outreach programme, inspiring the next generation of scientists and bringing the excitement of fundamental science to the wider public. 

Contact us

Please contact Prof. Andrei Andreyev and Dr. Stefanos Paschalis for further information on the project. 

Apply now

Theory of the nuclear proton-neutron pairing

  • Supervisor Professor Jacek Dobaczewski
  • Funding Awaiting funding decision
  • Application deadline 31st May 2019 or until a suitable candidate is found. 

Many nuclear observables can be explained in terms of the presence of a condensate of like-nucleon Cooper pairs in nuclei. However, nucleons form two types of condensate: made of the standard isovector (T=1) pairs and much less known isoscalar (T=0) pn pairs. The T=1 condensate manifests itself in nuclei with a variety of phenomena, but what about the T=0 one? The overarching question of the proton-neutron (pn) theme is thus: is it possible to observe experimentally and describe theoretically the T=0 condensate? If yes, in which region of the nuclear chart would its signature be best visible?

A major scientific investigation is in progress in N~Z nuclei in the mass 90 region following publication of a Nature paper [1] that suggested that spin-aligned (T=0) pn pairs in the g9/2 shell formed significant components of the wave functions of low-lying states. To validate the hypothesis of a T=0 condensate, experimentalists are looking for observables that would decisively show the existence of such a condensate. Attempts to study the impact of spin-aligned T=0 pairs on experimental features, such as B(E2) transition rates and nucleon knockout cross-sections in neutron-deficient Pd, Ag, and Cd nuclei, are being led by York (submitted or planned proposals to the next RIKEN PAC and an accepted proposal at JYFL), which together with Stockholm have the world lead here experimentally.

At present, the Nuclear Energy Density functional (NEDF) theory is probably the most promising technique to back up this experimental effort with new theoretical input. This theory requires advanced theoretical technology, which is currently available only at York. Within the framework of the PhD thesis of A. Márquez Romero, we have focused on developing novel NEDF methods to study the T=0 pairing in detail. Very recently, within a solvable SO(8) model Hamiltonian, we were able to implement the NEDF techniques with full spin and isospin symmetry-restoration. We showed [2] that the obtained ground-state energies and deuteron-transfer matrix elements are almost identical to the exact ones given by this model.

This methodology, which is unparalleled worldwide, has to be now ported to a realistic setting of the full NEDF approach. To this end, we will put to STFC a request to extend Antonio’s PhD studentship by 6 months, till March 2020. However, we cannot expect that such an extension could cover the exploitation phase of the project. The latter requires a new PhD student, who should start in September 2019, so that the two have sufficient overlap to ensure a smooth continuation of the projected research. The potential success of the future knockout proposal in the Pd/Cd nuclei may crucially depend on having credible NEDF calculations for cross-sections. Strong interest in proton-neutron pairing at York, both among experimentalists and theorists, together with their outstanding expertise in this area, makes from this research an ideal subject for the next STFC grant application, and provides a key opportunity for high-impact publications. [1] B. Cederwall, et al., Nature 469, 68 (2011) [2] A. Márquez Romero, J. Dobaczewski, and A. Pastore, arXiv:1812.03927

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York Plasma Institute 

Below are specific projects but we always welcome new proposals for research projects. Please contact the research group if you have something else in mind. 

Fast ions from graphene with potential application spanning fusion and oncology

Proton and heavier ion acceleration using ultra-intense lasers is being widely investigated for pure science, plasma diagnostics, medical as well as fusion engineering applications. One approach to achieving higher proton and ion energies is to use thin targets, and perhaps the thinner the better. However, thin targets are easily destroyed by the so-called laser prepulse which arrives prior to the main laser pulse on all intense laser systems. The maximum proton energy achieved so far has been limited to several tens of MeV when using relatively thick, of the order of a micrometer, targets. This has been the case even though there has been a successful decade long development of laser technologies which provide higher contrast, higher intensity and higher energy laser pulses. Very recently, the use of thin (10-100 nm) targets with ultra-intense lasers has shown promise by accelerating protons and carbons ions up to higher energies. This proposal pursues this approach through a collaboration with teams in Japan and Taiwan to the development and shoot the ‘ultimate target’; a large-area suspended graphene foil which is as thin as one atom (order of 1 nm) and suspended across holes of 100 μm in diameter. Graphene has several features that make this a particularly exciting material for laser ion acceleration. It is: 1) the thinnest material known, 2) mechanically strong, 3) formed from carbon which is a biologically compatible material and so suitable for ion oncology, and 4) transparent and unaffected by a laser prepulse below intensities of approximately 1011 W/cm2. Large-area suspended graphene foil is uniform and flat, thickness control is exquisite offering nm-order accuracy by building targets graphene layer by layer. Longer term, target manufacture is relatively straightforward and cheap target mass produce seems possible. Very little material is ablated in a laser shot, making the material suitable for future high repetition rate (e.g. many Hz). Perhaps it will be a magical material? This project will develop experimental and computational tools to study carbon (and proton) acceleration from graphene targets. The work will be carried out at the York Plasma Institute and at large facilities in the UK, Japan and elsewhere. The project provides an excellent opportunity for collaboration and for exploring new ideas.

This project will be based at the University of York. Please contact Prof Nigel Woolsey for more information.

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Laser-driven fusion: the Polar Direct Drive Shock Ignition approach

Join Robbie Scott at the Central Laser Facility (STFC) and Nigel Woolsey in the Physics Department (York) and contribute to an international effort to achieve fusion energy gain through Inertial Confinement Fusion (ICF). This project will explore the possibility of using the National Ignition Facility (NIF) in the USA to pursue an advanced approach to ICF referred to as ‘polar direct drive shock ignition’.  The project will have a computational bias but is firmly based around the interpretation of experiments. You’ll have the opportunity to use advanced radiation hydrodynamic models to study implosions, and new computational techniques to address the complex physics associated with laser-plasma interaction and the effect of overlapping many laser beams to assess the impact of multiple overlapping beams

 

This is an exciting time, as NIF is in the process of acquiring the optics needed for polar direct drive and you’ll have the opportunity to collaborate on NIF experiments with the Universities of Rochester (who also operate the Omega laser) and Alberta. You’ll have opportunities to travel as well as develop expertise in computational and theoretical approaches and link this to an exciting experimental programme of work.


Currently, the NIF is configured to drive ICF experiments using indirect drive. Here the NIF beams (192 of them) enter both ends of cylindrical cavity, called a hohlraum, from the north- and south-poles to create a uniform x-ray drive. This x-ray, i.e. indirect, drive implodes a millimetre scale spherical capsule containing deuterium and tritium fuel placed at the centre of the hohlraum. In direct drive, there is no hohlraum, and laser beams irradiate the capsule directly. As the NIF beams are arranged around the north- and south-poles of a sphere, new optical elements are needed to shape the laser focal spots to create a so-called polar direct drive platform. Shock ignition separates the compression of the fuel from the process raising the fuel temperature to initiate nuclear fusion burn. In this scheme a strong shock is launched late in the compression phase and the collision of shocks close to the compressed capsule centre rapidly raises the temperature to hundreds of millions of Kevin. These temperatures are needed to ensure there are enough nuclear reactions to sustain a fusion burn.


For more information please contact Nigel Woolsey at nigel.woolsey@york.ac.uk and check his webpage at https://www.york.ac.uk/physics/people/woolsey/.

 

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Low temperature plasma induced CO2 conversion for green value-added chemical delivery and energy storage*

  • Supervisor Professor Timo Gans
  • Funding Self funded & fully funded positions available
  • Application deadline 31st January 2019

This multi-disciplinary project offers students the opportunity to carry out postgraduate research at the interface of physics and chemistry. The student will be based in the York Plasma Institute and will have access to a wide range of state-of-the-art facilities in the York Plasma Institute Laboratories.

Our previous and ongoing research in this area has already shown the extraordinary potential of low temperature plasma to efficiently convert CO2 (a waste product) into CO which is a valuable building block for the chemicals industry. CO is an inherently toxic gas, so a low temperature plasma based process for its in situ generation as and when required from relatively non-toxic CO2 offers a green approach to the use of CO.

Non-equilibrium atmospheric pressure plasmas offer an attractive technology for converting greenhouse gases into valuable chemical products. This is a particularly promising route for versatile energy storage in renewable energy power plants, exploiting solar or wind energy, towards a CO2 neutral energy economy. This project will focus on efficient conversion of CO2 to CO and O2, using low-temperature atmospheric pressure plasmas. While efficient conversion has already been empirically demonstrated, the fundamental mechanisms of the non-equilibrium chemical kinetics are complex, nonetheless crucial to lift this technology towards a new generation of chemical processing. Reaction and conversion pathways critically depend on the nonMaxwellian electron dynamics on nanosecond timescales and associated energy deposition through dissociation and rotational-vibrational molecular excitation processes. These processes are key for tailored properties since the non-equilibrium electron induced chemical pathways allow superior efficiency over nonselective energy deposition in classical thermal chemistry. The combination of our recently developed control strategies for tailored electron dynamics and our advanced pico- and nanosecond optical diagnostic techniques for electron properties and reactive species analysis are unique worldwide. Together with our advanced multi-scale computational techniques for the chemical kinetics we are ideally positioned to lead this newly emerging field with global impact.

In addition to optimising and studying the plasma used to convert CO2 into CO, the student will also be able to investigate the utilization of the produced CO as a chemical reagent. Whilst many catalytic reactions of CO are already well known, these have been carried out using ultra-pure CO. The CO produced by a low temperature plasma will inevitably contain impurities (oxygen, ozone etc.) and the effect of these on the catalyst and reaction needs to be determined.

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Low-temperature plasma nitrogen fixation for agricultural applications*

  • Supervisor Dr Deborah O’Connell
  • Funding Self-funded students only
  • Application deadline 1st September 2019

This collaborative inter-disciplinary PhD project involves innovative research at the interface of physics, environment, chemistry and biology. The student will be part of the York Plasma Institute in the Department of Physics, with access to state-of-the-art experimental and computational facilities. The project will be carried out in close collaboration with research groups in the Departments of Environment, Chemistry and Biology and the University of York. The project builds on a recently successfully collaborative project between the research groups. Low-temperature plasmas have established applications ranging from computer chips and mobile phones to spacecraft population and medicine. Low-temperature or ‘cold’ plasmas are weakly ionised gases far from thermodynamic equilibrium. They are composed of a few hot electrons (few eV or ~10,000 C), while the heavier ions and neutrals (the dominant component) are close to room temperatures. These plasmas offer many technological applications, primarily motivated by their efficiency to generate reactive species in ambient dry environments at low temperatures, otherwise not achievable.

Artificial nitrogen fixation, for synthesis of ammonia mainly for fertiliser production, is a very important and demanding chemical process consuming around 1 – 2% of the world’s annual total energy supply. It is well known that lightning in the atmosphere improves plant growth through nitrogen fixation. We can mimic this process through sustaining low-temperature plasmas in ambient air. Plasmas can convert atmospheric nitrogen and oxygen molecules into nitrates, which are dissolvable in rain or water aerosol, and can then be carried to the soil. A key advantage of using plasmas is sustainability and independence of chemical plant infrastructure and production supply chains.

Sustaining and tailoring plasmas in ambient air is challenging, as these plasmas are susceptible to thermal instabilities, which need to be controlled. This project will involve the application of experimental and simulation techniques to explore the production of relevant chemically reactive species in air plasmas, how they can trigger downstream chemical and biological processes, and associated enhanced plant growth. State-of-the-art recently developed diagnostic analytical techniques will be applied and further developed to quantify reactive species within the plasma phase, and their transport into water and soil.

The project is suitable for candidates interested in physical and analytical chemistry, spectroscopic techniques and free radical chemistry. Training will be provided in all areas, and a willingness to learn new techniques and disciplines are more important than any prior experience. The successful candidate will have at least a 2:1 honours degree in a relevant science or engineering subject.

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Low-temperature plasmas for electric propulsion*

  • Supervisor Dr James Dedrick
  • Funding Self funded & fully funded positions available
  • Application deadline  31st January 2019


Low-temperature plasmas are prevalent in modern technology and current applications include semiconductor processing, television displays and propulsions systems for spacecraft. This project provides the opportunity to undertake international, collaborative research in low-temperature plasma physics with application to electric propulsion.

Recent research efforts have driven the development of compact, long-lasting propulsion systems. To increase their power efficiency and longevity, the potential use of plasma thrusters that generate a chargeneutral exhaust plume is of significant interest. This is because a cathode neutraliser (as installed on ion engines and Hall thrusters) is no longer required to ensure charge neutrality of the spacecraft and prevent beam stalling.

To maximise power efficiency and performance, a detailed understanding of the plasma physics is crucial. Compact plasma thrusters present additional challenges due to their limited diagnostic access. This project will therefore utilise state-of-the-art optical and numerical techniques to further our understanding of the physical mechanisms that operate on nanosecond timescales and ultimately drive performance.

Based at the York Plasma Institute in the Department of Physics, the studentship offers the opportunity to collaborate with international research partners at the SP3 Laboratory, Australian National University (ANU) and the Computational Plasma Science and Engineering Group (CPSEG), University of Michigan. During a funded University of York studentship, the student will be a member of the low-temperature plasma team. Our laboratory undertakes diverse and high-impact research in fields including semiconductor processing, thin films, green energy, plasma medicine and electric propulsion.

For futher information please contact james.dedrick@york.ac.uk

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Unravelling the physics and chemistry of Plasma-Enhanced Pulsed Laser Deposition

  • Supervisor Dr Erik Wagenaars
  • Funding Self-funded students only
  • Application deadline 1st September 2019


Metal oxide thin films like ZnO, Al2O3 and TiO2 are widely used in industry in microelectronics, catalysts and display devices. Conventional techniques for the production of these films, such as pulsed laser deposition (PLD), chemical vapour deposition and physical vapour deposition, all suffer from a lack of fundamental understanding of the underlying physical processes and detailed control of the deposited film properties. The goal of this research is to overcome these limitations by introducing a new deposition technique that uniquely combines laser and electrically produced plasmas: Plasma-Enhanced Pulsed Laser Deposition (PE-PLD).

The PE-PLD process can be described as 3 phases with distinctly different physics involved: laser ablation, plume dynamics and interactions, and thin-film formation. These individual processes have been studied in isolation in some detail, but the multi-scale and multi-physics nature of the PE-PLD process means that linking these studies is challenging, limiting what can be learned practically about how to better control thin film production.

This project will focus on enhancing the understanding of the underpinning plasma physics and chemistry of PE-PLD. You will combine state-of-the-art multiscale numerical modelling with direct measurements of plasma properties performed in the YPI Laboratories. The overall aim of the research is to provide predictive knowledge of high-quality thin film production, superior to current empirical methods.

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