MPhys Projects

Trinity Term

2015

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ContentsForeword 5

Choosing your MPhys project 6Project allocation 6Project risk assessment 6Project assessment 6Examination Conventions 7Weightings for the MPhys and Papers 7Project Outcomes 7Project prizes 7

Timetable for students 8

Timetable for supervisors 9

MPhys project descriptions 10

Atomic and Laser projects 10A&L01 Experimental Quantum Computing in Ion Traps 10

A&L02 Langmuir probe for RF Plasmas 10

A&L03 Development and application of machine learning techniques to unveiling the non- linear dynamics of laser-fusion plasmas 10

A&L04 How big is a petawatt laser-accelerated “hot” electron? 10

A&L05 Guiding of relativistic intense laser pulses in plasma for fusion energy 10

A&L06 Amplificationofextremelaserpulsesin plasma by parametric scattering 10

A&L07 Photon acceleration in beam-driven wakefieldaccelerators 11

A&L08 Secure computing using quantum resources 11

A&L09 Implementation and Characterisation of an External Cavity Diode Laser 11

A&L10 Difference-frequency locking of a pair of diode lasers 11

A&L11 Simulating Ionization Potential Depression under Stellar-Like Conditions 12

A&L12 Chains of dipolar Rydberg atoms 12

A&L13 Quantum detection 12

A&L14 Electrostatic trapping and manipulation of non-spherical particle 12

A&L15 Optical quantum state generation 12

A&L16 Precise shaping of laser beams for trapping ultracold atoms 12

A&L17 tbc 12

A&L18 tbc 12

A&L19 Novelpolarisationstatesinfibrelasers 12

Atmospheric, Oceanic and Planetary Physics projects 13AO01 Signatures of Southern Hemisphere Natural Climate Variability. 13

AO02 Measurement of Isotopic ratios in the Stratosphere 13

AO03 Measurement of Trace Gases in the Stratosphere 13

AO04 Assessment of cloud-aerosal ina UK environmental database 13

AO05 The impact of stochastic parameterisation on s imulations of climate 14

AO06 Measuring Rossby waves in the atmosphere 14

AO07 Jet variability and the statistical moments of atmosphericflow 14

AO08 Long Term Trend Analysis of the Impact of Aerosals on Climate 14

AO09 Satellite based study of cloud and aerosal interactions 14

AO10 Super-parametrisation and chaotic dynamics in climate models 15

AO11 Sensitivity of an atmospheric convection model to the triggering perturbations 15

AO12 The evolution of a population of convective clouds as simulated by a predator-prey (Lokta-Volterra) equation 16

AO13 Measuring Volcanic Ash from Space 16

AO14 It takes two to tango? Instabilities of coupled fronts in coastal currents 17

AO15 How do feedbacks and coupling impact sea ice variability on seasonal time scales? 17

AO16 Effective wind forcing of the Antarctic Circumpolar Current 18

AO17 Ocean Heat Uptake and Transient Climate Change 18

AO18 Electrical effects on atmospheric infra-red absorption 18

AO19 Exploration of the Moon in the infrared using laboratory experiments and spacecraft data analysis 18

AO20 Measuring the Earth’s atmosphere from a novel small satellite infrared radiometer 19

AO21 Altimetric Imaging Velocimetry 19

AO22 Synchronized intra-seasonal and inter- annual oscillations in atmospheric angular momentum 20

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Contents Cont’d Contents Cont’dAO23 Seasonal phase-synchronisation of ENSO withinobservationsandtheMetOffice global climate model 20

AO24 Exploring interactions between climate change and economics with idealised integrated assessment models 20

AO25 Atmospheric dynamical factors underlying the UKfloodsofJanuary/February2014 21

AO27 How does better representation of uncertainty in land surface parameters improve forecasting of the 2003 European summer heat wave? 21

Astrophysics projects 22AS01 Measuring dark matter in galaxies 22

AS02 Star formation history of local galaxies 22

AS03 Characterising Asteroids with Spectroscopy on the PWTPhilip Wetton Telescope 22

AS04 Why do black holes launch relativistic jets 22

AS05 MultifieldInflation 22

AS06 Finding Pulsars with Next Generation Telescopes 23

AS07 Giant radio pulses from radio emitting neutron stars 23

AS08 Constraining Stellar Feedback with the Circumgalactic Medium 23

AS09 Stress-Tensor Induced Instabilities in Accretion Disks 23

AS10 Black-hole accretion and galaxy formation 24

AS12 Finding the most distant galaxies with the VISTA-VIDEO Survey 24

AS13 Dynamics of extrasolar planets 24

AS14 High-redshift disk formation 24

AS15 Observations of W Ursa Majoris Variables in NGC 188 with the Philip Wetton Telescope 25

AS16 tbc 25

AS17 Measurement methods for weak gravitational lensing 25

Biological Physics projects 26BIO01 Digital holographic microscopy for 3D tracking of bacterial swimming 26

BIO02 DNA Nanostructures 26

BIO03 DNA Nanostructures 26

BIO04 Structure/functionstudiesofionchannels 26

BIO05 Super-resolution optical STED microscopy 26

BIO06 DNA biosensors 26

BIO07 tbc 26

Condensed Matter Physics projects 27CMP01 Single photon sources in the blue – quantum dot physics 27

CMP02 Investigating the physics of coupled magnonic resonators at millikelvin temperatures 27

CMP03 Investigating magnon propagation in magnetic waveguides at millikelvin temperatures 27

CMP04 Investigating the spin pumping and inverse spin Hall effects at low temperatures 28

CMP05 Simulations of Solid State Matter Compressed to Planetary Interior Conditions 28

CMP06 Quantum properties of implanted muons 28

CMP07 Calculation of the magnetic properties of molecular magnets 28

CMP08 Micromagnetism of Thin Film Structures and Devices 28

CMP09 Growth and transport studies of topological insulator nanomaterials 29

CMP10 De-twinned single crystals: preparation and properties 29

CMP11 Preparation and characterisation of ferromagnetic topological insulators 29

CMP12 ExternalquantumefficiencyofPerovskite solar cells 30

CMP13 Non-contact temperature sensing 30

CMP14 Optical Optimisation of Multi-junction Solar Cells 30

CMP15 Surface acoustic wave resonators in the quantum regime 30

CMP16 Superconducting qubits in microwave cavities 30

CMP17 Hybrid solid state cavity QED 30

CMP18 Electronic structure of novel superconducting materials 31

CMP19 Exploring the electronic properties of the topological Dirac materials 31

CMP20 Torque magnetometry of novel superconductors 31

CMP21 Photoluminescence from organo metal halide perovskites 32

CMP22 Specificheatmeasurementsofquantum magnetsinappliedfieldandatlow temperatures 32

Interdisciplinary projects 33INT01 Making a plasma dry-etching system for micro-scalesuperconductorthinfilm patterning 33

INT02 Supernova remnants in the Galaxy 33

INT03 Supernova remnants in the Large Magellanic Cloud 33

INT04 Nuclear Resonance observed using Cold Electronics 33

INT05 Nuclear magnetic resonance (NMR) investigation of correlated metal oxides 33

INT06 Laboratory investigation of volcanic lightning mechanisms 34

INT07 Measuring Cerebrovascular Reactivity using Magnetic Resonance Imaging 34

INT08 Investigating the microstructure of iron deposition in the human brain using MRI 34

INT09 Modelling cancer cell growth in multicellular spheroids 34

INT10 Solid state radiation detector for environmental radioactivity monitoring 35

INT11 An Electronics Project 35

INT12 An Electronics Project 35

INT13 Geophysics and industrial applications for SQUID magnetometry 35

INT14 Very-high-energy gamma-ray astrophysics with the Cherenkov Telescope Array 35

INT15 Very-high-energy gamma-ray astrophysics with the Cherenkov Telescope Array 35

INT16 Cold Electronic Instrumentation for Single Microwave Photon Experiments 35

INT17 An electronics project: precise experimental control using an FPGA 35

INT18 Investigation of a low distortion oscillator 36

INT19 tbc 36

INT20 Adaptive percolation 36

INT21 Statistical Mechanics of human interaction in cities. 36

Particle and Nuclear Physics projects 37PP01 Study of the impact of cosmic-ray induced events in Liquid Argon detectors 37

PP02 The MicroBooNE detector 37

PP03 ATLAS Physics 37

PP0301 Beyond the Standard Model with Highly Energetic Jets 37

PP0302 Direct Measurement of the invisible width of the Z using ATLAS data 37

PP0303 Precise measurement of the W boson mass 38

PP0304 Measurement of Higgs boson production in decays to W bosons 38

PP04 Search for neutrinoless double beta decay at SNO+ 38

PP05 The Higgs as probe for new physics 38

PP06 Photon recognition algorithms for dark matter searches 38

PP07 Simulation of background sources on dark matter experiments 38

PP08 Dark Matter Direct Detection experiment Background simulation 38

PP09 Search for rare annihilation decays of B- mesons using the 3fb-1 LHCb Run I dataset 38

PP10 Reactor anti-neutrino measurements with the Solid experiment 39

PP11 Analysisoftwo-phaseflowpropertiesin thin evaporators 39

PP12 Study of detector alignment for future particle physics tracking detectors 39

PP13 Precisionparticlephysics:g−2 39

PP14 Radiaoactivity screeing for the LUX-ZEPLIN experiment 39

PP15 B0 Meson Tagging 40

PP16 Measuring the Caesium Flux Escaping an Ion Source Plasma 40

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PP17 Plasma Spectroscopy Measurements Using a High Resolution Optical Monochromator 40

PP18 Algorithmsforlongitudinalprofileimage reconstruction of femtosecond electron bunches 40

PP19 Improving sensitivity to Supersymmetry at the 13 TeV Large Hadron Collider 41

PP20 Meeting the LHC data challenge 41

Theoretical Physics projects 42TP01 Precision determination of fundamental electroweak parameters at the Large Hadron Collider 42

TP02 Searches for New Physics beyond the Standard Model at the LHC using ratios of cross-sections 42

TP03 Multilayer Networks 42

TP04 Chemical evolution of the Milky Way and Satellite Galaxies 42

TP05 Unveiling formation histories of massive elliptical galaxies from distribution functions 42

TP06 Probabilistic parameter determinations of stars or galaxies 43

TP07 Stress-Tensor Induced Instabilities in Accretion Disks 43

TP08 Topics in plasma physics and plasma astrophysics: turbulence, transport, magneticfields 43

TP09 Anyons and Topological Quantum Computing 44

TP10 Topological Statistical Mechanics 44

TP11 Fractional Quantum Hall Effect 44

TP12 TopicsinGeometryandGauge/String Theories 45

TP13 Designing synthetic molecular motors 45

TP14 Twitching motility of bacteria near surfaces 45

TP15 Orbits of globular clusters 45

TP16 Spiral structure using perturbation particles 45

TP17 Understanding the biophysics of DNA nanostructures 46

TP18 Understanding the biophysics of DNA nanostructures 4

Index 47

Appendix A 49

Foreword

The MPhys project, as a major part of the MPhys course has often been considered the most enjoyable part of the course. From the comments made by students over several years, many students get a real buzz from a good project.Readthisbookletcarefullytofindoutwhichprojectsareavailableandwhatyouhavetodo.

You will start your Major Option Classes and your MPhys project Michaelmas Term 2015. You may be given some reading or work to do over the long vacation, and you will therefore be a little better informed and prepared. Theprojectmaybeyourfirstinsightintolifeinaphysicsresearchgroupandbeachancetoseedevelopmentsatthecuttingedgeofthesubject.Itisalsoafirstlookatproblemswhosesolutionmaywellbeunknown,toboth you and your supervisor.

To get the most out of your project you must choose carefully and prepare well. Contact potential project su-pervisor early and please complete the project choice form (see Appendix A) by the end of 6th week.

Please do contact me or the Assistant Head of Teaching (Academic) if you have any questions.

Prof. Jonathan Jones, Head of the Physics Teaching Faculty

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Project prizes

(a) The Gibbs Prize for the best use of experimental apparatus in an MPhys project. (b)TheBPPrizeforthebestfinalyearTheoreticalPhysics Project. (c) The BP Prize for a project in Astrophysics. (d) The Johnson Memorial Prize for a project in Atmospheric, Oceanic and Planetary Physics. (e) The John Thresher Prize for a project in Particle and Nuclear Physics. (f) A prize for a project in Atomic and Lasers Physics. (g) A prize for a project in Condensed Matter Physics.(h) The MetaSwitch Network* Prize for the best use of Software in an MPhys Project. (i) The Rolls-Royce Prize for Innovation in an MPhys Project. (j) The Tessella Prize for Programming in software in a MPhys Project.(k) The Winton Capital Prize for Best MPhys Re-search Project.(l) The NTT Prize for the Best MPhys Project in Biological Physics.(m)TheMetOfficePrizeforaProjectinAtmos-pheric, Oceanic and Planetary Physics.

*formerly the Data Connection Prize

The meetings with the candidates have been provi-sionally scheduled for Monday and Tuesday of 5th week in Trinity Term. The precise criteria for the overallassessmentoftheprojectwillfinalisedbytheexaminers.Howthefinalprojectmarkiscalculatedwill be published in the Examination conventions produced by the examiners. The overall assessment embracesthequalitybothoftheunderlyingscientificwork and the presentation in the report.

The MPhys Project Assessment form will be pub-lishedontheExaminationMatterswebpagehttp://www.physics.ox.ac.uk/teach/exammatters beforethe end of Hilary Term.

Examination ConventionsThe Examiners are responsible for the detailed weightings of papers and projects. The precise detailsofhowthefinalmarkiscalculatedispub-lished on the Examination matters webpage at www.physics.ox.ac.uk/teach/exammatters.htm.Studentsarenotifiedbye-mailwhentheybecomeavailable.

Weightings for the MPhys and Papers

Theprecisedetailsofhowthefinalmarkiscalcu-lated is published in the Examination Conventions on the Examination matters webpage at www.phys-ics.ox.ac.uk/teach/exammatters.htm.

Project Outcomes

Theoutcomesofprojectsareveryflexibleandtheresults may not be precisely as described by the project description in this handbook. Remember that they are intended as an introduction to research and the unexpected often happens!

According to the QAA benchmark statements for physics ‘Open-ended project work should be used to facilitate the development of students’ skills in research and planning (by use of data bases and published literature) and their ability to assess critically the link between theoretical results and experimental observation’ ref.: Quality Assurance Agency for Higher Education, subject benchmark.

How to go about choosing a project

Around two thirds of the 4th year students may expect to be allocated one of their choices of project. For the remaining third we try to allocate a project in a similar area of interest and also taking the students choice of Major Options into account. Some projects are more popular than others, for instance projects relating to Biophysics, therefore you are advised to select carefully your lower choices. Perhaps there is a project that you would like to do, but this is not listed in the handbook, in which case you may approach potential supervisors with your ideas.

Please inform the Assistant Head of Teaching (Aca-demic) of the topic, the title and the supervisor, if you have made your own arrangements. You are also encouraged to write a short statement on the back of the choice form if you have any particular strengths or experience relating to your choices, or if you are choosing a project with your future career in mind.

Although every effort is made to include all pos-sible information about and on the MPhys projects offered, new projects may become available after the publication of the MPhys Projects Trinity Term 2014, and infrequently a project may have to be withdrawn. All changes will be communicated by e-mail.

Project allocation

Projects are allocated by the Assistant Head of Teaching (Academic) using the student’s choices on the Project Allocation: CHOICE FORM, see Appendix A.

For the allocation exercise, the student name and col-lege are hidden to prevent any bias. All the project choice forms are entered into an access database. All eight choices are listed in order of preference and additional comments are recorded.

For very popular choices we use the following procedure:

(i) Supervisors are consulted as they may be con-tacted by prospective students about the projects they are offering, although this is not essential for the allocation of the project. Supervisors’ input is essential in trying to match projects to students;

(ii) The outcome of the third year, Part B, ranking will also be used to assign students to projects;

(iii)Shoulditstillprovedifficulttoassignthepro-ject, each student who wishes to be allocated the specificprojectisassignedanumberandthenthewinner is drawn from a hat;

Choosing your MPhys project

(iv) The PJCC (Physics Undergraduate Consultative Committee) is also consulted on an annual basis about the process. If you are not happy with the MPhys project you have been allocated, you are encouraged to discuss other possibilities with the Assistant Head of Teaching (Academic).

Project risk assessment

Assessing risks is an essential element of training for project work. It is good practice for students and supervisors to complete the risk assessment as-sociated with the project before starting. Please see http://www2.physics.ox.ac.uk/study-here/mphys-and-ba-project-information.

Project assessment

A Project Assessment Committee is set up every year to assess all the MPhys projects. The assessors are appointed by the relevant physics sub-Departments, the Physics Department or less frequently from an-other department of the University. The assessors on this committee are usually not Physics Finals examiners, but they may serve in this capacity.

The expert (junior) assessor will generally come from the sub-department to which the project is as-signed and they will have more specialist knowledge inthefieldoftheproject,oronecloselyrelated.Thenon-expert (senior) assessor will generally work in a different area of physics from the subject of the report and will mark reports chosen from other phys-ics sub-Departments. Each written MPhys report will be assessed by a junior and a senior assessor.

Each MPhys candidate will be expected to attend a meeting (‘viva’) with the two assessors of their project to discuss the written report. The purpose of this meeting is to help the assessors with assessing the candidates written report. Crucially the meeting helps clarify any issues that the assessors have after having read the written report. The assessors will read the supervisor’s report on the project to learn whatspecialdifficultieswereencountered,theextentof the initiative shown by the candidates, and so on.

The meeting will last about 20 minutes and will be rather informal. It will not require the preparation of a special presentation; indeed no visual aids other than your report (and your log book, if appropriate) will be allowed. The candidate will be expected to start the meeting by giving a short summary of the project, typically not lasting more than a few minutes, followed by a question and answer period.

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Timetable for studentsTrinity Term 2015Week 0 Publication of the MPhys Projects Trinity Term 2014 http://www.physics.ox.ac.uk/teachBefore deciding on a project students are encouraged to discuss any projects, in which they are interested, with super-visors, but there is no obligation to do so and allocation of projects does not depend on doing this.

Week 6 Complete the Project Choice Form Physics Teaching Faculty (Fri 3 pm) [Hand in the Project Choice Form by internal post or by e-mail] July -August Provisional Allocation of Projects Third year results published and provisional allocations made Majority of MPhys Project allocations made

September Publication of the Project Allocation List http://www.physics.ox.ac.uk/teach Students read the introductory papers on their project Michaelmas Term 2015

Week 0 Publication of the MPhys Projects Handbook http://www2.physics.ox.ac.uk/students/undergraduates(Mon) [e-mailnotification] Talk to your college tutor about the project you have been allocated.

Weeks 1 & 2 Compulsory Safety Lecture and Risk Assessments Consult lecture list Completion and submission of your Risk Assessment Acknowledgement form. Compulsory attendance of the safety lecture. You will NOT be allowed to start your project if you have not completed and submitted your Risk Assessment Acknowledgement form to the Physics Teaching Faculty. Students meet supervisors to get instructions including alternate arrangements if the supervisor has to leave Oxford during the project period.

Week 3 Project period starts. Please note: the total effort devoted to the project should be equivalent to 20 working days full time activity, plus about six weeks for analysis, write up and literature review during Michaelmas and Hilary terms. Students should discuss with the supervisor(s) a project plan to accommodate both their project and Major Option ClassesStudents need to understand that outcomes of projects are uncertain and the project may change from the description originally provided. Projects are an introduction to research and are not necessarily predictable. Weeks 7 Discuss plan of project report with supervisor(s). Students must prepare a short progress report (onesideofanA4sheetofpaper)outliningplanfortheprojectand/orliteraturereview.Thismust be handed into the Physics Teaching Faculty. This progress report is for your College tutors.

Hilary Term 2016 Weeks 1 - 8 MPhys project period continues Week 2* ‘How to write an MPhys Project Report’ lecture Please consult the lecture list for details

Week 3 or 4 Talk to your college tutor about the progress of your project.

Week 9 Hand in a draft ( as complete as possible) of MPhys report to your supervisor. You and your supervisor must complete and sign the MPhys Draft Form (see Appendix A). Week 10 Deadline for receiving comments from supervisor.The schedule for handing in the draft report and receiving comments can be changed by mutual agreement. Please let Carrie Leonard-McIntyre know of changes of more than one week. Trinity Term 2016Week 1 MPhys project reports handed in. Examination Schools(Mon 12 noon) Three copies of project or essay & the Declaration of Authorship & a copy of the report in pdf format on a CD. (One of these copies will be given to the supervisor for their record.)*subject to change, see lecture list

Hilary Term 2015

Week 1-8 Call for MPhys Projects starting in Michaelmas Term 2015 starts. E-mail

Trinity Term 2015

Week 1 Publication of the MPhys Projects Trinity Term 2015 http://www2.physics.ox.ac.uk/students/undergraduatesStudents may contact you to learn more about your projects. They are not obliged to do this and the allocation of projects is not in any way dependent on them doing so.

July -August Provisional Allocation of Projects Third year results published and provisional allocations made.

September Publication of the Project Allocation List http://www2.physics.ox.ac.uk/students/undergraduates Students read the introductory papers on their project

Michaelmas Term 2015

Weeks 1 & 2 Compulsory Safety Lecture and Risk Assessments Consult lecture list Completion and submission of your Risk Assessment Acknowledgement form. Compulsory attendance of the safety lecture. Students will NOT be allowed to start their projects if they have not completed and submitted their Risk Assessment Acknowledgement form to the Physics Teaching Faculty. Students meet supervisors to get instructions including alternate arrangements if the supervisor has to leave Oxford during the project period.

Week 3 Project period starts. Please note: the total effort devoted to the project should be equivalent to 20 working days full time activity during Michaelmas and Hilary terms. [Guidance: the total effort devoted to the project should be equivalent to 20 working days full time activity, plus about six weeks for analysis, write up and literature review during Michaelmas and Hilary terms.] You must discuss with the student(s) the project plan to accommodate both their project and Major Option Classes. Weeks 7 Discuss plan of project report with your supervisor.(s) Student to have prepared a short progressreport(onesideofanA4sheetofpaperoutliningplanfortheprojectand/orliteraturereview

Students need to understand that outcomes of projects are flexible and the project may change from the descrip-tion originally provided. Projects are not necessarily predictable and can be an introduction to research.

Hilary Term 2016

Weeks 1 - 8 MPhys project period: during this period all of the experimental and theoretical work necessary for the project should be completed. You should meet the student regularly and leave your contact details for the student to contact you should the need arise. You should encourage the student to begin the project write-up as early as possible. Week 9 Full as possible draft of the MPhys report handed in by student to you and MPhys Draft Form (see Appendix A). The completion of the MPhys Draft Formconfirmsthatthedraftreporthasbeenseen and the form must be sent to Physics Teaching Faculty, signed by both student and supervisor. Please notify the Physics Teaching Faculty of any delay in returning the completed form. Week 10 Comments by supervisor on draft report is given to the student.

Trinity Term 2016Week 1 MPhysStudenthandsincopiesofthefinalreporttoExaminationSchools.Week 2 Deadline for return of Supervisor’s Report Form.

Timetable for supervisors

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MPhys project descriptionsAtomic and Laser projects

A&L01 Experimental Quantum Computing in Ion Traps

This will be a lab-based project contributing to apparatus development for experiments in trapped-ion quauntum computing.Thespecificworkwilldependonthestatusofour research at the time. Please contact Dr D.Lucas d.lucas@physics.ox.ac.uk for more info about details of the project, andseewww.physics.ox.ac.uk/users/iontrapforbackgroundinformation about the research group.Supervisor: Dr D Lucas Email: d.lucas@physics.ox.ac.uk

A&L02 Langmuir probe for RF Plasmas

Low temperature RF plasmas is used extensively in the manufacture of computer chips. Here a low pressure gas such as Ar is turned into a plasma between two RF electrodes driven with at 13.56MHz. The Ar ions crash into the silicon substrate placed on the driven electrode and etch the vari-ous transistor channels into the silicon surface. The plasma density ne and temperature Te are critical parameters and are measured using Langmuir probe. Various types exist but the most compact have been developed here at Oxford and have RF compensation applied at just the right amplitude and phase to the probe tip. The probe I-V curve is obtained by applying a sawtooth wave to the probe and plotting the resulting curve on a computer. Analysis of the curve allows ne, Te to be measured. This project will involve using LAB-VIEW and a DAC along with building circuits to generate the voltage waveform V and measure the current I so obtaining the probe I-V curve digitally. Additionally, as part of the project, software would then be written to analyse the various sections of the I-V curve to obtain ne, Te. Your probe will be tested for you in a RF rig here at Oxford. Supervisor: Dr G Gregori Email: g.gregori1@physics.ox.ac.uk

A&L03 Development and application of machine learn-ing techniques to unveiling the non-linear dynamics of laser-fusion plasmas

Extreme states of plasmas are created when intense laser pulses are shone onto matter. Controlling these plasmas, having temperatures >10,000,000 C and pressures > billion atmospheres, opens the way to new cancer therapies, possible fusion energy sources, as well as many studies of fundamen-talhighfieldphysics.Inthisproject,wewilladvancethestate of the art by developing and applying machine learning (ML) techniques to data from advanced kinetic simulations. We will begin by analysing the dynamical trajectories un-dertaken by particles under these extreme conditions, using supervised and unsupervised ML techniques to classify and cluster like trajectories and identify topical mechanisms of particle acceleration.Supervisor: Prof P Norreys Email: Peter.Norreys@physics.ox.ac.uk

A&L04 How big is a petawatt laser-accelerated “hot” electron?

Petawatt (1015 W) lasers are the most powerful light sources on earth, and as a consequence of their illumination of dense matter, copious numbers of electrons are accelerated to near the speed of light. All applications of petawatt laser technol-ogy,includinginertialconfinementfusionenergysourcesandmedical ion beam sources, make use of these “hot” electrons in one manner or another. In spite of this fact, the precise number of hot electrons accelerated by the laser is unknown, mainly due to the nonlinear conditions of the interaction. In this project, we will apply recent analytical advances to derive the cross section for hot electron acceleration in topi-cal situations, to be informed and validated using advanced kinetic simulation codes.Supervisor: Prof P Norreys Email: Peter.Norreys@physics.ox.ac.uk

A&L05 Guiding of relativistic intense laser pulses in plasma for fusion energy

Remarkable progress towards the realisation of controlled fusion energy has been made recently using the National Ignition Facility in the United States [H.S. Park et al., Phys. Rev. Lett. 112, 055001, (2014); O. Hurricane et al., Nature (London) 506, 343 (2014)]. There physicists have used exquisite control of the laser pulse drive shape to drive an appropriately shaped black-body radiation drive to both compress and heat isotopes of hydrogen to fusion conditions. These papers show that dramatic progress is being made in understanding the underlying physics, but obstacles still remain. My team have looked recently at supplementing the deposited energy in the hot-spot surrounding the compressed fusion fuel by precision stopping of relativistic electron beams generated by petawatt laser pulses. The concept looks very promising and we have proposed a “proof-of-concept” experimentusingtheORIONlaserfacilitytomakethefirstdemonstration in the laboratory. The student will help in the design of this experiment by undertaking a computational and theoretical study to determine the best position for focusing these petawatt laser pulses in the coronal atmosphere. The ideaistopreventbeamfilamentationandallowwhole-beamself-focusing to occur and direct most of the accelerated energy into the hot spot. Supervisor: Prof P Norreys Email: Peter.Norreys@physics.ox.ac.uk

A&L06 Amplification of extreme laser pulses in plasma by parametric scattering

One limitation for practical applications of intense laser pulses is the requirement for very large optics to operate within known damage limits. One possible route to over-comingtheseobstaclesistouseparametricamplificationinplasma. The use two counter-propagating intense laser pulses promises a revolution in energy and peak power delivery. My team is working closely with colleagues at America’s leading optics laboratory, the Laboratory for Laser Energet-ics at the University of Rochester, New York, to design the

firstlarge-scaledemonstrationofthisconcept.Thestudentwill use sophisticated computer simulations to help in the designoftheseedlaserpulsetooptimiseitsfidelityduringamplificationandalsowithsubsequentdataanalysis.Supervisor: Prof P Norreys Email: Peter.Norreys@physics.ox.ac.uk

A&L07 Photon acceleration in beam-driven wakefield accelerators

The AWAKE project at CERN is starting in 2016 and uses the Super Proton Synchrotron beam (450 GeV energy) to drive a largeamplitudeplasmawakefieldacceleratingstructureover10mdistance.Theaimoftheprojectistofindanewroute to a TeV e-e+ collider, making use of existing infra-structure in the Large Hadron Collider. A method to diagnose theformationofwakefieldsthereistousetheconceptofphoton acceleration, which occurs when a co-propagating laser probe pulse experiences changes in the refractive index of the plasma. This project is to develop further the photon acceleration diagnostic with oblique angles of incidence, instead of co-propagation. In this case, there is a lower bound for the crossing angle. If the angle is less than this limit, the interaction distance will be longer than the Rayleigh length of the modulated part of the probe pulse. This means that it has already started to expand while interacting with the wakefield.Thatcausesthemeasurementtoreadlowervaluesthanitshould.Theobjectiveistofindtheanalyticalexpres-sion relatingplasmawakefielddensity and the frequencymodulation of the laser pulse for this case. The student will also need to check the expression by doing 2D particle-in-cell simulations of high performance computing platforms. Supervisor: Prof P Norreys Email: Peter.Norreys@physics.ox.ac.uk

A&L08 Secure computing using quantum resources

This project will study secure universal classical comput-ing in quantum networks, including multiple clients and servers. It has been shown theoretically that using quantum resources, basic classical computations can be delegated securely by just sending single qubits. In previous work, we have experimentally demonstrated the delegation of a secure classical computation, a classical NAND gate, by sending single qubits or laser light only.

This project aims for performing multi-party computations, where a server computes a function f(x1, x2,…,xn) with inputs xi from different clients, for example a secure sum. A sketch of the envisioned protocol for the computation is shown in Fig. 1. The server generates simple computational resources, such as single qubits, and sends them consecu-tively to a number of different clients. Each client manipu-lates the computational resources, for example by performing phase gates. In the end, the server measures the output state, from which he can deduce the results of the computation, a sum in our case.

We plan to implement this protocol with single photons, generated on a chip, basic integrated waveguide circuits, and standard single-photon avalanche photo diodes.

The project is interdisciplinary; the student should have a strong interest in quantum information processing, both in theory and experiment, as well as in fundamental computer science. The student will perform initial theoretical calcu-

lations, and identify and order experimental components needed for the experiment, setup the experiment and write software for the experimental control. At the end of the project, we expect a presentation of the work in our research group. We expect the student to participate in our group meetings and to communicate with our research team. At the same time, the student should be able to work independently to a certain degree and be self-motivated.

The project will open up new possibilities for general multi-party computations. It outlines an important application of quantum technologies in the sense that quantum resources can be useful, without the need for developing a full-scale quantum computer.

Fig. 1: Concept of a classical delegated computation using quantum resources

Supervisors : Dr S Barz and Prof I Walmsley Email: Stefanie.Barz@physics.ox.ac.uk, i.walmsley1@physics.ox.ac.uk

A&L09 Implementation and Characterisation of an External Cavity Diode Laser

This project is focussing on the assembly and operation of a grating-stabilized diode laser system in the Littrow configuration, and the subsequent characterisation of thissystem using Fabry-Perot interferometers and absorption spectroscopy in Rubidium vapour.Supervisor: Dr A Kuhn Email: a.kuhn@physics.ox.ac.uk

A&L10 Difference-frequency locking of a pair of diode lasers

The beat note between two independent lasers will be used to detect and monitor their difference frequency, and to lock it to an ultra-stable radio-frequency reference. The locking circuitry is primarily based on radio-frequency electronics. Once the lasers are locked, these will be used for driving Raman transitions in Rubidium.Supervisor: Dr A Kuhn Email: a.kuhn@physics.ox.ac.uk

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A&L11 Simulating Ionization Potential Depression under Stellar-Like Conditions

Half-way to the centre of the sun the density is about the same of that of water, but the temperature is of order 100 eV (i.e. about a million Kelvin). Under such conditions matter is clearly a plasma - a sea of ions and electrons. One ques-tion that has been puzzling physicists for years is what the ionisation potential is for an ion embedded in such a dense, hot, environment. Clearly ionisation can occur just due to atoms being close to one another (like a cold metal), but it also occurs due to temperature. The ionisation potential evidently differs from that of the free atom or ion. Recent experiments in our group have shown how to make plasmas under these conditions (albeit for about 100 femtoseconds), and sophisticated atomic-kinetics simulations can also be performed to predict observed spectra. In this project the student will perform such simulations, using different models for the depression of the ionisation potential, with the aim of providing guidance for future experiments.

Reading

Vinko et al, Nature, 482, 59 (2012)

Ciricosta et al, Phys. Rev. Lett., 109, 065002, (2012)Supervisor: Prof J Wark Email: J.Wark1@physics.ox.ac.uk

A&L12 Chains of dipolar Rydberg atomsMore details from the supervisor.Supervisor : Prof D Jaksch Email : d.jaksch@physics.ox.ac.uk

A&L13 Quantum detection

Quantum physics promises to revolutionize a wide range of applications, such as measurement precision beyond the classical limit, secure communications, and exponentially fast information processing. At the heart of these quantum-enhanced technologies lies the concept of a quantum experi-ment. A quantum experiment can be divided into three stages: state preparation, processing, and measurement. The optimal performance of quantum-enhanced technologies relies on the ability to reliably characterize quantum states. For opti-cal quantum technologies this involves the use of detectors sensitive to subtle quantum features, such as photon counting detectors. In this project we will develop an experimental approach to detect quantum properties of light.

Thorough understanding of quantum mechanics and classical optics is required for the project. Prior experience with lasers and experimental optics will be looked upon favorably. A solid background knowledge of classical optics - particularly Fourier optics - will also be essential. Computer program-ming skills (LabVIEW and Matlab) to interface experimental equipment, acquire and analyze data will also be helpful.Supervisor: Dr B Smith Email: b.smith1@physics.ox.ac.uk

A&L14 Electrostatic trapping and manipulation of non-spherical particleMore details from the supervisor.Supervisor : Prof C Foot Email : Christopher.Foot@physics.ox.ac.uk

A&L15 Optical quantum state generation

Quantum physics promises to revolutionize a wide range of applications, such as measurement precision beyond the classical limit, secure communications, and exponentially fast information processing. At the heart of these quantum-enhanced technologies lies the concept of a quantum ex-periment. A quantum experiment can be divided into three stages: state preparation, processing, and measurement. The optimal performance of quantum-enhanced technologies requires the ability to reliably produce quantum states. For optical quantum technologies this involves the generation of non-classical states of light, such as single-photon states. In this project we will develop an experimental approach to reliably generate quantum light sources using ultrashort laser pulses for quantum-enhanced technologies.

Thorough understanding of quantum mechanics and classical optics is required for the project. Prior experience with lasers and experimental optics will be looked upon favorably. A solid background knowledge of classical optics - particularly Fourier optics - will also be essential. Computer program-ming skills (LabVIEW and Matlab) to interface experimental equipment, acquire and analyze data will also be helpful.Supervisor: Dr B Smith Email: b.smith1@physics.ox.ac.uk

A&L16 Precise shaping of laser beams for trapping ultracold atoms More details from the supervisor.Supervisor : Prof C Foot Email : Christopher.Foot@physics.ox.ac.uk

A&L17 tbcMore details from the supervisor.Supervisor : Dr P E G Baird Email : p.baird@physics.ox.ac.uk

A&L18 tbcMore details from the supervisor.Supervisor : Prof A Steane Email : a.steane@physics.ox.ac.uk

A&L19 Novel polarisation states in fibre lasers It has been recently shown that electrons can be acceler-ated in vacuum using tightly focused radially polarised lasers. Such particle acceleration schemes avoid the use of large rf cavities or complex plasma interactions. The radial polarisation states are usually generated with expensive, specialist optics that are very lossy and create imperfectly polarised beams. In this project the student will work on a novel experiment to directly create a radially polarised beam byrecombininghigherordermodesinafibreamplifier.Theproject is predominantly experimental and best suited to a student studying the C2 Lasers course, but there will also be theoretical and numerical studies of these polarisation states and their production. Familiarity with programs such as Matlab and LabView would be useful but not essential.Supervisor : Dr L Corner Email : Laura.Corner@physics.ox.ac.uk

Atmospheric, Oceanic and Planetary Physics projects

AO01 Signatures of Southern Hemisphere Natural Climate Variability.

Several studies have looked at the impact of solar variabil-ity and volcanic eruptions at the Earth’s surface, including work here at Oxford led by Professor Gray. One approach has been to use multiple linear regression, including indices to represent, for example, the 11-year solar cycle, volcanic eruptions and long-term trends associated with greenhouse gases. A recent study highlighted that, for example, the im-pact of 11-year solar variability on mean sea level pressure (mslp)andseasurfacetemperatures(SST)intheEuropean/N. Atlantic sector was lagged by a quarter cycle i.e. 3-4 year. Thishasparticularpotentialbenefitsforlong-term(seasonal,decadal) forecasting since the 11-year solar cycle can be reasonably well forecast and may therefore give valuable additional capability for seasonal forecasting over Europe. A mechanism for this lag has been proposed, in collaboration withMetOfficecolleagues,involvinganinfluenceonthemixed layer of the ocean in winter that can be perpetuated through to the following summer and thus provides a posi-tive feedback.

In recognition of the importance of seasonal forecasting over Europe, previous effort has been focused on the Northern Hemisphere winter response over Europe. However, there are some interesting signals apparent in the Southern Hemi-sphere that deserve attention, and also in summer time in both hemispheres. In this project we plan to expand the sphere of interest, to examine to examine the Southern Hemisphere response. This will be carried out using existing tools, pri-marily the multiple linear regression employed in previous studies. The study will examine the Hadley Centre mslp and SST datasets. There is also the potential to collaborate further withMetOfficecolleagues,whohaveasetofclimatemodelensembles for the period 1960-2010 with and without a solar cycle in the imposed irradiances, so that mechanisms may be further explored.

Skills required

This project is entirely computer-based, examining both observational and climate modelling data requiring experi-enceofUNIXandIDL/Python.Supervisor: Prof L Gray Email: Gray@atm.ox.ac.uk

AO02 Measurement of Isotopic ratios in the Stratosphere

Some of the major infrared absorbing molecules in the atmos-phere are assumed to maintain their surface ratios of minor isotopes, e.g. fraction of CO2 molecules with 13C atoms com-pared to the normal 12C. Others, e.g. H2O, are known to vary due to the mass-dependence of various chemical processes.

The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) is part of the payload of the European Space Agency’s ENVISAT satellite launched in March 2002. MIPAS is a fourier-transform spectrometer which measures the infrared emission spectra of the earth’s atmosphere from 4-15micronswithsufficientspectralresolutiontoidentifyminor isotopic lines of a number of different molecules.

This project is to investigate simple techniques which can be applied to such spectral signatures to extract isotopic ratios, and compare the results with previous measurements or predictions.

The project is entirely computer-based so some knowledge ofscientificcomputingand/orlinuxwouldbeuseful.Supervisor: Dr A Dudhia Email: dudhia@atm.ox.ac.uk

AO03 Measurement of Trace Gases in the Stratosphere

The Infrared Atmospheric Souding Interferometer (IASI) is a nadir-viewing fourier transform spectrometer on the Metop satellites. Although primarily designed for detecting emission features from CO2,H2O and O3 for use in numerical weather prediction, the measurements also contain spectral features from a number of minor species such as CH4 and CO.

The aim of this project is to investigate fast detection tech-niques for identifying spectra where the concentrations of these minor gases is enhanced compared to normal back-ground. This starts by constructing covariance matrices of sets of IASI spectra taken from the same geographical location and attempting to extract signals associated with the spectral features of the target molecules.

The project is entirely computer based, and related to the remote sensing, radiative transfer and inverse methods parts of the C5 option.Supervisor: Dr A Dudhia Email: dudhia@atm.ox.ac.uk

AO04 Assessment of cloud-aerosal ina UK environ-mental database

It is clear from ship tracks that human activities can alter the properties of clouds. Aerosols (i.e. suspended particles such as dust, soot, or sea salt) act as nucleation sites for cloud droplets such that their introduction to a cloud increases the number of droplets and decreases their average size, known asthefirstindirecteffect.Variousaerosol-cloudinteractionshave been proposed, but the experimental evidence quantify-ingtheunderlyingphysicsisfarfromdefinitive.

The Chilbolton Facility for Atmospheric and Radio Research (CFARR)isafieldsiteinHampshirehostingavarietyofradars, lidars, radiometers, particle counters, and other me-teorological sensors. The wide variety of collocated instru-ments, with observations since 2006 and earlier, provides a unique dataset with which to thoroughly evaluate various atmospheric phenomenon, their interactions, and the ac-curacy with which they can be observed.

This project aims to investigate the evidence for cloud-aerosol interactions in CFARR data. It will concentrate on the variation of cloud base height and precipitation as a function of wind speed, direction, and aerosol loading but will evolve in response to the student’s results and their sci-entificinterests.Theprojectiscomputerbased,requiringtheanalysis and presentation of diverse data. Experience with the Linux operating system and the IDL or Python program-ming languages would be an advantage but is not essential.Supervisors: Dr A Povey and Dr R G Grainger Email: a.povey@physics.ox.ac.uk,r.grainger@physics.ox.ac.uk

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AO05 The impact of stochastic parameterisation on simulations of climate

Computer simulations of past, present and future climate based on the laws of physics are very important for un-derstanding and predicting weather and climate change. Directly calculating the effects of important small-scale features such as clouds and turbulent eddies requires much more computing power than is available, however, and so thesefeaturesarerepresentedusingsimplified“parameteri-sations”, which estimate the small-scale state based on the calculated large-scale state. However, many small-scale states could exist for any given large-scale state, so there is fundamental uncertainty in the parameterisations. “Stochastic parameterisations” include random components to account for this uncertainty, and have been shown to improve numeri-cal weather forecasts.

Recently, stochastic parameterisations have also been shown to improve the representation of “regimes” in the climate system – states in which the climate system lingers, which are associated with prolonged periods of anomalous weather, and which have been argued to play an important role in shaping the pattern of climate change.

The aim of this project is to investigate further the differences in regime behaviour in weather and climate models with and without stochasticity in their parameterisations, and the effect that this has on climate change projections. The student will analyse existing data from simulations performed using the ECMWF IFS weather and climate model.

This project would best suit a student who is happy to analyse data using a computer language such as python, Matlab or IDL, though no prior experience of using these languages is necessary.Supervisors: Dr P Watson and Prof T PalmerEmail: Watson@atm.ox.ac.uk,t.palmer@physics.ox.ac.uk

AO06 Measuring Rossby waves in the atmosphere

Weather patterns in the mid-latitudes are dominated by Ross-by waves which consist of trains of alternating cyclonic and anticyclonic vorticity anomalies. There are several methods for identifying and measuring Rossby wave variability in the atmosphere, but these can lead to quite different results. For example, some simple methods have suggested that Rossby waves are changing as a result of the strong recent warming of the Arctic, yet other methods disagree. This project will examine a small sample of real atmospheric data to test how well some different methods work in characterising Rossby waves. The work will consist of reading and interpreting scientificpapersandsimplecomputerprogrammingwithalanguage such as Matlab.Supervisor: Dr T Woollings Email: Woollings@atm.ox.ac.uk

AO07 Jet variability and the statistical moments of atmospheric flow

Atmospheric flow exhibits clear structures in its higherstatistical moments such as the skewness and kurtosis. His-torically these have been interpreted as signs of nonlinear flow such as the repeated occurrence of distinctweatherregimes. However, recent evidence suggests that some of these features can be reproduced in much simpler systems, in

particular in the presence of varying jet streams. This project will develop some very simple jet models, using a kinematic and/orvorticity-basedapproach.Theflowstatisticsofthesemodels will then be compared with observed patterns from the real atmosphere. The work will consist of reading and interpretingscientificpapersandsimplecomputerprogram-ming with a language such as Matlab.Supervisor: Dr T Woollings Email: Woollings@atm.ox.ac.uk

AO08 Long Term Trend Analysis of the Impact of Aerosals on ClimateGlobal warming is expected to continue into the future due to the steady rise of greenhouse gases emitted by anthropogenic activities. Part of this warming is masked by the cooling ef-fect of aerosols that are emitted alongside these greenhouse gases. The extent of this aerosol-driven cooling is largely uncertain due to complex interactions between aerosol and cloud. Obtaining accurate estimates of the radiative effects of aerosol in the climate system is essential to understanding climate change.The Oxford-RAL Aerosol and Cloud algorithm (ORAC) retrievalhasbeenfittoprovideaconsistentrecordofaerosoland cloud retrievals that now span multiple decades (from 1995 to 2012). This data set provides a unique opportunity to study the long-term trends of aerosol-cloud interactions and improve our understanding of these interactions and their associated uncertainty in the climate system. The sensitivity of pertinent cloud properties (e.g., cloud albedo) to changes inaerosolindexwillfirstbeexaminedforselectedregionsofinterest and then extended to the globe. An inter-comparison study including other satellite sensors,for example, MODIS (MODerate resolution Imaging Spec-troradiometer) will also be conducted.The student will have the opportunity to deepen their computer programming skills, learn about and discover the theory behind aerosol cloud interactions, and use state-of-the-art satellite retrievals combined with a radiation model to quantify the aerosol indirect forcing. While basic computing skills in a programming language would be advantageous they are not required.Supervisors: Dr M Christensen and Dr R G GraingerEmail: matthew.christensen@stfc.ac.uk, r.grainger@physics.ox.ac.uk

AO09 Satellite based study of cloud and aerosal in-teractions

Cloudsandaerosols in theatmospherehavea significanteffect on the Earth’s radiation budget with either a cool-ing or a warming effect depending on vertical location and composition. The interaction between clouds and aerosols represents one the greatest sources of uncertainty in climate change studies. Aerosols affect the formation of clouds alter-ing their life cycle and potential for precipitation.

The Oxford-RAL Aerosol and Cloud (ORAC) algorithm uses satellite based image measurements, from both polar orbiting and geostationary platforms, to retrieve properties of clouds and aerosols. The use of one code for both cloud and aerosol provides the potential to study cloud and aerosol together and in particular their interaction. The aim of the project to use of ORAC to study cloud and aerosol interactions, e.g. data could be analyzed to reveal how Asian pollution advected overthenorthPacificaffectscloudproperties.

The project tasks include, choosing a set case studies that cover range of climates and cloud and aerosol types, ob-taining all the input satellite data and the various required ancillary datasets, running ORAC on these cases to retrieve cloud and aerosol properties, producing a combined cloud and aerosol product, analysis of the products. The project is computer based and will involve using Linux and a high level programming language, such as Python (with NumPy, SciPy, and Matplotlib) or the Interactive Data Language (IDL), for reading, analyzing, and plotting data. Prior experience in these would be useful but is not required.Supervisors: Dr G McGarragh and Dr R G GraingerEmail: mcgarragh@atm.ox.ac.uk, r.grainger@physics.ox.ac.uk

AO10 Super-parametrisation and chaotic dynamics in climate models

Modelling the evolution of Earth’s future climate, as accu-rately as possible, is one of the most challenging problems in climate physics and computational science. It is also of utmost importance and urgency, so that our society can adapt to the projected changes in future climate. In current day climate models, one of the biggest challenges is to represent clouds well. The parametrised cloud processes in today’s climate models lead to the largest source of uncertainty in future projections of climate change. The challenge of repre-senting cloud processes comes from their multi scale nature with spatial and temporal scales ranging from microphysical interactions (cloud droplets) to planetary scale interactions (such as hurricanes).

A recent novel and successful approach to improve upon previous approaches of parametrisation of clouds has been a multi-scale modelling framework better known as super-parametrisation in the climate modelling community. The idea is to embed a cloud-resolving model inside a global low-resolution climate model. Motivated by this approach, we will use a two-dimensional atmospheric model developed by Ed Lorenz (pioneer of chaos theory) in 1996. The Lorenz-96 model is an often used simple model for studying chaos in a simple system that resembles atmospheric dynamics. We will use a version of this model that has two time-scales of variability ( a fast time-scale representing weather and a slow time-scale representing climate). We have implemented a version of super-parametrisation in this model, to parametrise the effect of the fast time-scales on the slow time-scale vari-ables yet resolve some of the dynamics of the fast scales.

In this project, the student will analyse this model to build insights into the chaotic behaviour of the super-parametrised dynamics compared to the original two-scale fully non-linear model and identify differences in the evolution of the model dynamics both on short and long time scales. These lessons will then be used to improve upon super-parametrisation, using ideas from stochastic modelling to capture the non-linear chaotic dynamics of the system better. The overarching scientificobjectiveistoidentify,explainandcorrectfordif-ferences in the non-linear dynamics of a super-parametrised model as compared to a fully non-linear model. We have fresh ideas on how to approach the problem in a targeted way to achieve the goals of the project.

There may be opportunity for an interested student to also analyse simulations of a super-parametrised real climate model and study differences in its dynamics from a deter-

ministic and stochastic parametrised climate model. This is not a core element of the project, but would be accessible to students making good progress. The project will involve programming in MATLAB or equivalent software for plot-ting, analysis and modifying the model. We have versions of both a super-parametrised and a fully non-linear Lorenz-96 model and intend to use the same for this study. No prior experience of using MATLAB or analysis of non-linear dynamical systems is necessary.Supervisors: Dr A Subramanian and Prof T PalmerEmail: subramanian@atm.ox.ac.ukt.palmer@physics.ox.ac.uk

AO11 Sensitivity of an atmospheric convection model to the triggering perturbations

Convection is responsible forasignificant fractionof thecloud cover and precipitation in the earth’s atmosphere, and therefore plays an important role in both weather and climate. However, individual cumulus clouds and thunderstorms are much too small to be resolved directly by numerical simula-tion on a global scale. Global climate models therefore use “parameterisations” which estimate the convective behaviour inasimplifiedstatisticalsensetocalculateitseffectonthelarger scale.

Convection is triggered by localised buoyancy perturbations near the surface, but the nature and magnitude of these per-turbations is itself based on unresolved small-scale processes such as turbulence, land surface variations and feedbacks between clouds. In this project, the student will evaluate the sensitivity of the recently-developed Convective Cloud Field Model (CCFM) to variations in how these unresolved buoyancy perturbations are prescribed.

CCFM differs from many widely-used convection param-eterisations in that it explicitly simulates the updraught velocity within convective clouds.

This is crucial for capturing interactions with atmospheric aerosol, which are a major source of uncertainty in climate projections. As well as looking at effects on the frequency and strength of convection, one of the aims of this project is to determine how dependent the in-cloud updraught is on the choice of triggering perturbations. This will help to assess the robustness with which CCFM can simulate these aerosol-convection interactions.

It is envisaged that the project will begin by exploring a range offixedparametervalues,butthatthestudentwillthendrawon literature and theoretical considerations to develop a more sophisticated approach to selecting perturbations, potentially involving links to boundary-layer meteorology, stochastic effectsand/orthepropagationofconvectivesystems.

The student will work primarily with CCFM in an idealised configuration,buttherewillbescopeforafinalexperimentin the global model to assess the implications of their work for climate simulation.

The project will involve running and adapting a model written in the Fortran programming language on the Linux operating system. Prior experience with either of these would be useful, but not essential.Supervisors: Dr Z Kipling and Prof P StierEmail: kipling@atm.ox.ac.uk,philip.stier@physics.ox.ac.uk

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AO12 The evolution of a population of convective clouds as simulated by a predator-prey (Lokta-Volterra) equation

Atmospheric convection is the main driver of vertical redis-tribution of moisture and energy and is an essential part of the water cycle. It has feedback on the large-scale dynamics, and is a key process for the weather and climate. An accurate prediction of convection processes in weather and climate models is hence essential to anticipate its impacts.

However, representing convection in the models is very challenging as it imply a wide range of scales, from the size of a turbulent eddy which might trigger convection to the size of a cloud, and up to mesoscale convective complexes which can spread over several hundred of kilometers. All these scales cannot be resolved in a general circulation model (GCM) of the atmosphere, which has a typical resolution of 100 km, and hence they have to be parametrised. The chal-lenge of convective parametrisation is to represent the effect of convection in terms of variables on the limited resolution of the host model. It raises many questions and issues with many ways to answer them, making the parametrisation of convection being a modeler’s dream… or nightmare.

The most common approach to address this issue in global atmospheric models is to simulate a single cloud representing the average effect of all the clouds existing in the gridbox [e.g. Tiedtke, 1989]. Other approaches, following the pioneer work of Arakawa and Schubert [1974], consider a popula-tion of clouds. The later approach is computationally more expensive, but allow to represents the variability within a gridbox. For instance, instead of an average convective precipitation, different cloud type can produce different precipitation rates within the gridbox. The Convective Cloud Field Model, CCFM [Wagner and Graf, 2010] is based on this idea, and simulates, within a gridbox, a population of clouds of different radii, updraft velocities and in-cloud properties. In CCFM the spectrum of clouds is calculated by solving a Lokta-Volterra equation (predator-prey equation), the differ-ent cloud types (clouds of different size) competing for the available potential energy.

Project

CCFMwillbeusedinsimplifiedidealizedcases,toexplorethe sensitivity of the clouds characteristics on changes in the profilesoftemperatureandmoisture.Forinstance,someofthe question to address would be:

•Howdoesthecloudspectrumevolvewithincreasingavail-able potential energy?

•CanCCFMreproduceobservedcloudregimes,forinstanceshallow and deep convection?

Depending on the interest of the student the idealized simula-tions could also be complemented by theoretical work on the properties of the equation. The convergence and unicity of the solution has been proven in a more general form of the Lokta-Volterra equation [Champagnat et al., 2010], however underaspecificassumptionwhichisnotrespectedinCCFM.Interesting work could hence be done on the properties of theequationspecificallyinthecontextofCCFMorpossiblymore widely.

A step further could be to address the pertinence of the simulatedfield by comparingwith observations or othermodel studies, but this beyond the scope of the current MPhys project.

CCFM is used in the Climate Processes group within the climate model ECHAM-HAM and its single column ver-sion. A better understanding of its characteristics in idealized simulations, along with some theoretical work, could lead to further improvements of CCFM, and their implementation in the climate model. A global run of ECHAM-HAM with CCFM could be done at the end of the project.

Requirements

As CCFM is already in use in a climate model and its single column version, the student will have the opportunity to start using it very quickly.

Knowledge of a programming language, like Fortran and Python or Matlab would be an advantage, as well as some experience of working on a Linux environment but this can be compensated by enthusiasm.

Any interest in theoretical development / appliedMaths(ordinary differential equations) is welcome.

Bibliography

Arakawa, A., and W. H. Schubert (1974), Interaction of a Cumulus Cloud Ensemble with the Large-Scale En-vironment, Part I, J. Atmospheric Sci., 31(3), 674–701, doi:10.1175/1520-0469(1974)031<0674:IOACCE>2.0.CO;2.

Champagnat, N., P.-E. Jabin, and G. Raoul (2010), Con-vergence to equilibrium in competitive Lotka–Volterra and chemostat systems, Comptes Rendus Math., 348(23–24), 1267–1272,doi:10.1016/j.crma.2010.11.001.

Tiedtke, M. (1989), A Comprehensive Mass Flux Scheme for Cumulus Parameterization in Large-Scale Models, Mon.WeatherRev.,117(8),1779–1800,doi:10.1175/1520-0493(1989)117<1779:ACMFSF>2.0.CO;2.

Wagner, T. M., and H.-F. Graf (2010), An Ensemble Cu-mulus Convection Parameterization with Explicit Cloud Treatment, J. Atmospheric Sci., 67(12), 3854–3869, doi:10.1175/2010JAS3485.1.Supervisors: Dr L Labbouz and Prof P StierEmail: Labbouz@atm.ox.ac.uk,philip.stier@physics.ox.ac.uk

AO13 Measuring Volcanic Ash from Space

During the eruption of Eyjafjallajökull satellites played a vital role in monitoring the ash cloud. One of the major source of uncertainty in the satellite estimates was the exact composition of the ash The published infrared spectral re-fractive index of volcano-related ash and rock shows a large variability, presumably because of the changing mineral and silicateratioswithintheash.Thisisreflectedinthevariabilityof the measured IR spectra from satellite instruments (such as IASI) for different volcanic eruptions.

The spectral range of 1000-1100 cm-1 presents the maximum variability of the volcanic ash transmittance as a function of ash composition, and it is underexploited mainly because of the presence of additional variability introduced by stratospheric ozone absorption. In this project the student will improve the present IASI ash retrieval scheme with the inclusion of the ozone band spectral region. The student will addtheozoneprofile(fromECMWF)dataintotheIASIfor-ward model, expand the IASI ash retrieval scheme and test if this addition increases the information on ash composition.

The project is computer based. It will involve the analysis and display of satellite data, requiring some simple program-ming in IDL. Some experience with the Linux operating systemand/ortheIDLprogramminglanguagewouldbeanadvantage but is not essential.Supervisors: Dr E Carboni and Dr R G GraingerEmail: carboni@atm.ox.ac.uk, r.grainger@physics.ox.ac.uk

AO14 It takes two to tango? Instabilities of coupled fronts in coastal currents

Whenlargefreshwaterriversflowoutintotheocean,theyoften form coastal currents which propagate hugging the coastline, in an approximate geostrophic balance dominated by the Coriolis effect due to the Earth’s rotation. In some settings, coastal currents are fed by several different river outflows,leadingtoamulti-layersystemofneighbouringcurrents with different densities separated by sharp density fronts. Recent laboratory analogue experiments have con-sidered the dynamics of two neighbouring coastal currents ofdifferentdensities,flowingatopadensesalineoceaninan initially axisymmetric geometry. After the initial adjust-ment towards geostrophic balance, an instability develops resulting in the formation of a range of spiral vortex pat-terns, which differ depending on the imposed initial state. Beyond being an aesthetic example of pattern formation in a nonlinear system, such instabilities and vortex development can have key implications for the dispersion of nutrient rich waters or chemical contaminants between a coastal current and ocean interior.

This project aims to develop a theoretical understanding of the instability and pattern formation in systems with neigh-bouring coastal currents separated by sharp density fronts. The project will start by carrying out a linear stability analysis of the coupled dynamics of 2 neighbouring low-density cur-rents, with the aim of predicting the characteristic length and timescalesfortheflowdevelopmentandunderstandingthephysical mechanisms that drive the observed instability. The theoretical results can be compared to data from laboratory experiments carried out by collaborators at the Woods Hole Oceanographic Institution. Further extensions of the work might either consider the dynamics of 3 or more coastal cur-rents, or an analysis of the nonlinear interactions between the evolving density fronts to determine whether they dance in step, or oppose each others action.

This project would suit a student interested in applying theoretical modelling approaches to understand instabili-tiesinafundamentalfluiddynamicalproblemrelevanttoocean dynamics.

In addition to the mathematical analysis of the stability problem, the student will have the opportunity to learn more about numerical methods for stability problems, involving solving differential equations and eigenvalue problems. Whilst prior experience with a programming language such asMATLAB/Fortran/C/etc.wouldbeanadvantage, thereis potential for a motivated student to learn the necessary skills during the project. Supervisors: Dr A Wells Email: wells@atm.ox.ac.uk

AO15 How do feedbacks and coupling impact sea ice variability on seasonal time scales?

Physical feedbacks between atmosphere, ocean and sea ice are of major importance for the weather and climate of the high latitudes. Natural sea-ice variability acts on a large range of spatial and temporal scales and is driven by a com-bination of the internal variability of the atmospheric and oceanic forcing, the internal dynamics and thermodynamics of the ice, as well as coupled feedbacks between ice, ocean and atmosphere. Due to the complexity of these processes large uncertainties remain in current climate models when it comes to simulations and forecasts of the sea ice cover in polar regions.

This project aims to improve understanding of the sources and magnitude of sea ice variability and the related uncer-tainties in a fully coupled atmosphere-ocean-sea ice model. The focus will be on feedback mechanisms and the relative significanceofseaiceprocessesonseasonaluptointerannualtime scales. To this end, model output will initially be pro-vided from an ensemble of integrations of a state-of-the-art climate model, describing the evolution of key sea ice vari-ables.Therelativesignificanceofthevariousfeedbackscanbeidentifiedbyconsideringresultsofnumericalexperimentswith different configurations of themodel,where certainfeedbacks or physical processes are either switched off , orelsereplacedbysimplifiedorstochasticcomponentstosimulate reduced or enhanced variability, or include meas-ures of model uncertainty. The project will initially involve analysingthesemodeldatatobetterunderstandtheinfluenceof the feedback mechanisms and the coupling on seasonal time scales. Results will be compared to previous studies and will aim to improve future model simulations or identify the sources and limits of sea ice predictability. After the initial analysis and interpretation of simulation data, there are a range of possible extensions. The student could suggest (or run)newsimulationsandmodelconfigurations to furtherinvestigate key processes or test model improvements. New hypotheses could be tested using models of varying com-plexity, such as developing a low-order dynamical systems model that captures the leading-order physical feedbacks, or incorporating new developments into the fully coupled climate model.

This project would suit a student interested in learning about physical processes and feedbacks in the climate system in the polar regions, the implementation of complex climate models and extracting novel physical insight from the analysis of large data sets. The student should be capable of investigat-ing into newfindings using available data by employingdiagnosticsofvaryingcomplexity.Itwouldbebeneficialifthe student were familiar with a programming language (such as Matlab) for the implementation of the diagnostics, but it will also be possible to acquire the necessary skills during the course of the project. Supervisors: Dr A Wells and Dr S Juricke Email: wells@atm.ox.ac.uk, Juricke@atm.ox.ac.uk

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AO16 Effective wind forcing of the Antarctic Circum-polar Current

The Antarctic Circumpolar Current (ACC) transports 137 x 106 m3 s-1 of water around Antarctica, connects the different ocean basins and has a profound impact on climate. Despite this, we lack a convincing theory of the processes that set the volume transport of the ACC. The dominant mechanical forcing of the ACC is believed to come from surface wind forcing, though most of the wind work occurs north of the open latitude band of Drake Passage. In this project, the student will study a new approach is estimating the effective wind forcing of the ACC through a rotational-divergence decomposition of the surface wind stress. The project will involve a combination of pen and paper and mainly compu-tational work with a simple numerical model. The ultimate goal is to develop a simple conceptual model of how wind forcing sets the volume transport of the ACC.

The project will involve a combination of work with simple pen and paper models and simple computational models coded in Fortran. No previous experience of programming is required, although a general aptitude for computational work would be a distinct advantage. Supervisor: Prof D Marshall Email: d.p.marshall@atm.ox.ac.uk

AO17 Ocean Heat Uptake and Transient Climate Change

The ocean is one of the primary natural factors mitigating the human impact of climate. It is a “sink” for over 30% of carbon emissions from fossil fuel burning and 90% of the excess heat trapped by atmospheric CO2. The ocean heat uptake has long been recognised as critical in setting the pace of climate change and is likely responsible for the recent “hiatus” in global warming. However, observations and coupled general circulation model simulations suggest that the geographic pattern of uptake is neither uniform nor steady. On time scales longer than a few decades, the ocean can also be a source (rather than a sink) of anthropogenic CO2 and heat but as these tracers are transported via ocean circulation back to the surface where they can impact the atmosphere and hence climate. Understanding the physical processes setting the uptake of heat and carbon by the ocean and their pathways between the surface and the interior is thus a critically important problem in climate science.

The aim of the project will be to quantify the role of the atmospheric forcing (e.g., wind, temperature) and the ocean circulation in the regional uptake of heat and carbon and as-sess the feedback of the ocean onto global mean temperature change. The primary tool will be the mathematical machinery of Green functions, which allows to describe the advective-diffusivetransportoftracersinanygeophysicalfluidsuchas the ocean and atmosphere. Green functions allow us to rigorously quantify ventilation, ocean interior pathways and subsequent re-emergence of water “tagged” with climatically important tracers such as heat and anthropogenic CO2. The student will calculate and simulate Green functions (and their adjoint) in idealised and in complex models.

This project will suit a student with an interest in fundamen-tal climate dynamics. Some basic Matlab and Fortran code will be provided as a starting point. Previous experience with Matlab would be an advantage but is not required.

Suggested Reading:

Meehl et al, 2011, Model-based evidence of deep-ocean heat uptake during surface-temperature hiatus periods. Nature Cli-mateChange,1,360–364,(2011),doi:10.1038/nclimate1229

Marshall and Zanna: A Conceptual Model of Ocean Heat Uptake under Climate Change. J. of Climate, 27, 8444-8465

Khatiwala, S., F. Primeau, and T. Hall, 2009: Reconstruc-tion of the history of anthropogenic CO2 concentrations in theocean.Nature,462,346-349,doi:10.1038/nature08526.

Holzer, M., and T.M. Hall, 2000: Transit-time and tracer-agedistributionsingeophysicalflows.J.Atmos.Sci.,57,3539-3558, doi:10.1175/1520-0469(2000)057<3539:TTATAD>2.0.CO;2.Supervisors: Dr L Zanna and Dr S Khatiwala Email: zanna@atm.ox.ac.uk; samar.khatiwala@earth.ox.ac.uk

AO18 Electrical effects on atmospheric infra-red absorption

The effects of cosmic rays on weather and climate are poorly understood, as highlighted in the most recent Intergovern-mental Panel on Climate Change report (2013). Molecular cluster-ions created by cosmic rays in the atmosphere have been shown to absorb infra-red radiation in a band near 9um in laboratory spectroscopy experiments. Atmospheric infra-red absorption has also been associated with high-energy particles that create atmospheric ions (e.g. Aplin and Lockwood, Env. Res. Letts., 2013). This project will involve data analysis to investigate the physical relationships and mechanisms linking atmospheric infra-red absorption to other atmospheric electrical parameters. Students applying for this project should be studying the Atmospheric Phys-ics option and Particle Physics would also help (but is not essential). They should also be able to, or willing to learn, to write code in a data analysis package such as IDL or R.Supervisor: Dr K Aplin Email: k.aplin@physics.ox.ac.uk

AO19 Exploration of the Moon in the infrared using laboratory experiments and spacecraft data analysisIn the last ten years, exploration of the Moon from orbit has experienced a dramatic resurgence - with new missions from the US, China, India and Japan. The new measure-ments delivered by these new missions are revolutionising our understanding of the Moon, as well as what it can tell us about the formation and evolution of the Solar system. At Oxford Physics we helped build one of the instruments on NASA’s Lunar Reconnaissance Orbiter, the Diviner Lunar Radiometer (Diviner), and are now working on the large dataset being returned form the Moon. Diviner is similar to a specialised thermal infrared camera - measuring the lunar surface environment and composition - and this project will help analyse these new compositional measurements, com-paring to laboratory experiments we are currently carrying out here in Oxford.The project has the potential to involve both laboratory work and data analysis. The lab work will include preparing and measuring mineral samples that are similar to those found on the Moon, measuring them in our infrared Fourier-transform spectrometers under simulated lunar conditions, and then

applying the results to measurements made by the Diviner instrument in orbit around the Moon. In particular, we are interested in how different combinations of minerals found in the lunar surface affect the data measured by Diviner, so this project will produce results that will have a direct im-pact on our understanding of how the Moon’s crust formed and involved. A more data-focused project would involve working with measurements made by Diviner to improve our understanding of how the roughness and slopes on the lunar surface affects our interpretation of the compositional results. Both projects will require use of computers and some programming experience will be an advantage.

Recommended reading: Planetary Sciences (de Pater and Lissauer), Diviner website (www.diviner.ucla.edu) and Lunar andPlanetaryInstitutewebsite(www.lpi.usra.edu/lunar).Supervisors: Dr N Bowles and Dr K Donaldson HannaEmail: bowles@atm.ox.ac.uk, DonaldsonHanna@atm.ox.ac.uk

AO20 Measuring the Earth’s atmosphere from a novel small satellite infrared radiometer

Smaller spacecraft cost less to launch and operate, and have been leading a small revolution in how remote sensing data can be gathered from Low Earth Orbit compared with conventional large operational spacecraft. Oxford Phys-ics, working with colleagues at the Rutherford Appleton Laboratory (RAL), have designed and built a small infrared radiometer (the Compact Modular Sounder) to measure the composition and temperature of the Earth’s atmosphere as part of the UK’s TechDemoSat-1 spacecraft, successfully launched in 2014. The instrument’s main task is to demon-strate that an infrared instrument on a small satellite can de-liver the same, well-calibrated data products as an instrument on a larger spacecraft, and incorporates several novel new bits of technology developed in the department and at RAL.

The Compact Modular Sounder (CMS) has now been op-erational for ~8 months and we have loads of new data to explore. This project will provide you with an insight into how data from a new instrument is calibrated, converted into a useful data product and then analysed to help solve problems in weather forecasting and climate monitoring. The firstpartoftheprojectwillbetohelptheteamatOxfordand RAL convert the raw measurements from CMS into data with pointing (i.e. latitude and longitude) and radiances whicharenecessaryforscientificexploitation(derivationof atmospheric properties) of the data. This conversion activity will be ongoing throughout the project and is likely to evolve as the spacecraft operations team at Harwell get used to running the mission! Once we have a mapped data product, the project will then build on the material covered in the C5 ‘Physics of Atmospheres and Oceans’ major option tocalculatesomeexampleatmospherictemperatureprofilesand surface temperature maps from the new dataset, using sophisticated radiative-transfer software tools developed in-house at Oxford Physics and used extensively in the analysis of Earth, planetary and exoplanetary data. This project will require use of computers and some programming experience will be an advantage. It should be of high interest to students interested in working in the space industry on instrument development and/or applications of satellite data for botEarth observation and planetary exploration.

Recommended reading: Elementary Climate Physics, (Taylor), The Physics of Atmospheres (Houghton), C5 Major option lecture notesSupervisors: Dr N Bowles and Dr J Hurley (RAL Space)Email: bowles@atm.ox.ac.uk, hurley@atm.ox.ac.uk

AO21 Altimetric Imaging Velocimetry

Inarapidlyrotatingfluid,thepressurefieldiscloselycon-nected to the horizontal velocity via the geostrophic balance relation. In a shallow layer of fluidwith a free surface,dynamicalvariationsinpressurearereflectedinvariationsin the height of the surface. Such variations in the surface elevation of the Earth’s oceans may be on the order of cm - metres, and are now routinely measured by radar altimetry from orbiting satellites. On a laboratory scale, however, these perturbationstothefreesurfacemaybeextremelysmall(<<1mm)anddifficulttomeasure.

In this project, we will set up an optical system to measure andmapsuchsmallperturbationstotheinterfaceinaflowpattern obtained under laboratory conditions. Rhines, Lin-dahl & Mendez (2007) have recently demonstrated a novel method of measuring the free surface elevation of a rotating fluid,byusingitasaparabolic,Newtoniantelescopemirrorto form an image of a carefully designed light source in a CCTV camera. Small perturbations from dynamical mo-tionsinthefluidresultindistortionsofanimagereflectedfrom the free surface that can be used to determine the local elevation to a precision of 1 micron or better. This project will use the method of Rhines et al. (2007) to study and measuresimple,barotropicallyunstableflowpatternssetupin a cylindrical tank on a rotating table. Colour images from this experiment will be calibrated and analysed using a set of MatLab software provided by researchers at the Universities of Washington and Newfoundland.

The student will therefore need good experimental skills and some computing ability to make use of (and possibly extend) existing analysis software for image processing and diagnostics.

Suggested Reading:

Andrews, D.G., “An introduction to atmospheric physics”, Cambridge University Press, 2000

Rhines, P. B., Lindahl, E. G. & Mendez, A. J. 2007 “Optical altimetry:anewmethodforobservingrotatingfluidswithapplications to Rossby- and inertial waves on a polar beta-plane”, J. Fluid Mech., 572, 389-412, 2007

Afanasyev, I., P.B.Rhines and E.G.Lindahl, 2009: Velocity andpotentialvorticityfieldsmeasuredbyaltimetricimagingvelocimetryintherotatingfluid.,ExperimentsinFluids,May2009,doi:10.1007/s00348-009-0689-3.Supervisor: Prof P Read Email: p.read@physics.ox.ac.uk

AO22 Synchronized intra-seasonal and inter-annual oscillations in atmospheric angular momentum

The total axial angular momentum of the Earth’s atmosphere

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isobservedtofluctuatesignificantlyontimescalesrangingfrom~1dayto>2years.Thisresultsfromchaoticand/orcyclic variability in atmospheric motions associated with exchanges of angular momentum between the atmosphere and the underlying planet, producing changes in the Earth’s length of the day of the order of milliseconds. Time series of the angular momentum of the atmosphere have been de-rived for a number of years now which provide a powerful, yet still quite unusual, way of investigating how different components of the climate system interact with each other.

In this project, we will make use of a relatively novel dataset of atmospheric angular momentum for the Earth, derived from observations analyzed by the US National Meteorologi-cal Center, that has been partitioned into a series of separate latitude bins. This enables us to investigate the possibility of coupling between atmospheric oscillations (periodic or chaotic) in zonal wind patterns originating in different parts of the world. The data will be analyzed, for example, to ex-plore possible links between the tropics and other latitudes on timescales from ~20 days to 2 years. The project will make innovative use of data analysis techniques that are designed to detect and characterize partially synchronized oscillations between two or more different systems. It is thereby hoped to identify patterns of oscillation that are coherent across the globe, and perhaps link them to well known oscillatory phenomena in the climate system, such as the Quasi-Biennial Oscillation (originating in the stratosphere with a period ~2 years) or the so-called Madden-Julian oscillation in the tropi-cal troposphere (thought to be driven by tropical convection on timescales ~30-60 days). Such synchronized behavior is not well understood, but may be important for guiding new insights into the variability (and predictability) of the climate system, with possible implications for unravelling natural from man-made climate changes.

This is primarily a data analysis project that will make use of computational techniques derived from the theory of nonlin-ear dynamical systems to manipulate and analyze data time series. The student will therefore need to be comfortable with utilizing computational packages such as IDL or MatLab.

Suggested reading:

Pikovsky, A., Rosenblum, M. & Kurths, J. (2001) Synchroni-zation: a universal concept in nonlinear sciences, Cambridge University Press.

Read, P. L. & Castrejon-Pita, A. A. (2010) Synchronization in Climate Dynamics and Other Extended Systems, in Non-linear Dynamics and Chaos: Advances and Perspectives (eds. Thiel, M.; Kurths, J.; Romano, M.C.; Károlyi, G.; Moura, A.), Springer, ISBN 978-3-642-04628-5, pp. 153-176.

Dickey J. O., Ghil M., Marcus S. L. (1991) Extratropical aspects of the 40-50 day oscillation in length-of-day and atmospheric angular momentum. J. Geophys. Res., 96, 22643-22558.

Read, P. L. & Castrejón-Pita, A. A. (2012) Phase synchroni-zation between stratospheric and tropospheric quasi-biennial and semi-annual oscillations, Q. J. R. Meteorol. Soc. 138, 1338–1349. Supervisor: Prof P Read Email: p.read@physics.ox.ac.uk

AO23 Seasonal phase-synchronisation of ENSO within observations and the Met Office global climate model

The most prominent large-scale mode of climate variability occursinthetropicalPacificocean,andischaracterisedbysea-surface temperature (SST) anomalies migrating across thePacific,aphenomenonwhosephasesareknownasElNiño/LaNiña.Theatmosphererespondstothesemigratingregions of warm and cold SST with anomalously active areas of convection, corresponding to areas of low and high pressure. Together these closely linked processes constitute a phenomenon known as the El Niño Southern Oscillation (ENSO). The migrating SST anomalies oscillate to and fro with a period of roughly a few years. It is well known that the El Niño phase builds up during the northern hemisphere summer, peaking in northern winter, and so is linked with the seasonal cycle. Recent work has suggested a more subtle correspondence between the seasonal cycle and developing ENSO phases, whereby El Nino is purported to synchronise its phase with the annual cycle. In this project we will fur-ther examine the possible phase-synchronisation of ENSO withinobservationsandlongsimulationsoftheMetOfficeglobal climate model.

The student will use a combination of complex time series analysis, including Hilbert transforms, to examine for the presence (or otherwise) of phase-synchronisation within tropical ocean variability. The project will introduce, and require the use of, the IDL programming language and the handling of large climate datasets.

Suggested reading:

Pikovsky, Rosenblum M. & Kurths, J., Synchronization: A Universal Concept in Nonlinear Sciences, Cambridge Nonlinear Science Series (2003)

Stein K., A. Timmermann and N. Schneider, “Phase Syn-chronization of the El Niño-Southern Oscillation with the Annual Cycle”, Phys. Rev. Lett. 107, 128501 (2011)Supervisors: Dr S Osprey and Prof P Read Email: sosprey@atm.ox.ac.uk; p.read@physics.ox.ac.uk

AO24 Exploring interactions between climate change and economics with idealised integrated assessment models

Integrated assessment models (IAMs) are widely-used tools for climate change policy development, addressing questions such as determining the level of carbon tax re-quired to achieve a particular environmental goal, such as stabilising temperatures at 2 degrees above pre-industrial. The behaviour of current IAMs is surprisingly linear, pos-siblyreflectinglimitedscopefornon-linearbehaviourinthesimplifiedclimatemodelsonwhichtheyarebased.Morecomplex climate models, however, do not consistently point towards large-scale non-linear responses, at least over the coming century. A potentially more serious problem is the IAM’s rather limited representation of potentially non-linear feedbacks between climate change and the rate of economic growth. While there is a literature dating back decades on non-linear climate change and an entirely separate literature on non-linearity in macro-economics, much less has been written on possible non-linear interactions between the two. This project will begin from a simple linear climate model coupled to idealised representations of global damage and the

global economy to explore how interactions between climate change and economic growth might result in interesting behaviour in IAMs, such as bifurcations (“tipping points”) between different climate policy regimes.

The student will have to be familiar with the chaos com-ponents of the B1 course. Having attended the S:25 option would be helpful, but not essential (notes are on weblearn). Familiarity with some form of mathematical programming language such as matlab or IDL would be helpful, and an in-terest in economics and interdisciplinary problems essential.

Background reading: The Climate Casino: Risk, Uncer-tainty, and Economics for a Warming World by William Nordhaus Supervisors: Prof M Allen Email: myles.allen@ouce.ox.ac.uk

AO25 Atmospheric dynamical factors underlying the UK floods of January/February 2014

Thewinterof2013/2014experiencedexceptionallyheavyrainfall in southern England, with Oxford experiencing its wettest winter since the Radcliffe Observatory record be-gan in 1767. Working with Environment Guardian, Oxford has conducted a unique large-ensemble public distributed computing experiment to examine the possible role of hu-maninfluenceonclimate in theseevents:http://www.cli-mateprediction.net/weatherathome/weatherhome-2014/Thisexperiment has generated tens of thousands of simulations of “possible weather” in two ensembles, one representing present-day conditions, and the other representing a range of possibilities for the “world that might have been” had human-induced climate change not occurred. Thus far, these ensembles have only been explored for changes in occurrence-frequency of heavy UK rainfall events, but also contain a wealth of information on the dynamical factors (atmospheric circulation patterns, sea surface temperatures, etc)thatpotentiallyplayedamajorroleinthesefloods.Thisstudent project will explore the circulation patterns associ-ated with heavy rainfall events in these ensembles, and as-sess to what degree the atmospheric model used is capable of simulating these circulation anomalies realistically. We would expect this student to take the C5 option.Supervisors: Dr F Otto and Prof M AllenEmail: friederike.otto@ouce.ox.ac.uk, myles.allenn@ouce.ox.ac.uk

AO27 How does better representation of uncertainty in land surface parameters improve forecasting of the 2003 European summer heat wave?

The land surface has an important role in the climate system, primarily through evaporation and its effect on latent and sensible heat fluxes.This land-atmosphere couplingwasparticularly strong in 2003 over Europe, when negative spring soil moisture anomalies contributed to the exceptional summer heat wave.

The potential to anticipate heat waves is made possible by climate models run in seasonal forecasting mode. Here the initialization of slowly varying components of the climate system enables predictability of average conditions, months ahead. Uncertainty in the land surface component of these models is not well represented, and ongoing work at Oxford and the European Centre for Medium-Range Weather Fore-casts (ECMWF) is addressing this issue.

Recent hindcasts experiments indicate by perturbing two key land surface parameters in the ECMWF’s state-of-the-art seasonal climate model we improve the simulation the 2003 European summer heat wave. However the mechanism by which this arises is not currently understood.

The goal of the project then is to diagnose the mechanisms leading to this forecast improvement, as well as to investigate any systematic effect of the land surface parameters on the model simulation. There is the also the possibility to extend the analysis to alternative years and regions. This project offers the student experience working with large datasets, as well as a good introduction to seasonal climate forecasting andverification.

Special skills:

The project will require programming the handling, analysis and visualization of climate model data. The student should either have a basic knowledge of Linux and a language such as NCL, matlab or python, or be willing to learn these.

Suggested reading:

Troccoli, A. (2010), Seasonal climate forecasting. Met. Apps, 17:251–268.doi:10.1002/met.184

Weisheimer, A., F. J. Doblas-Reyes, T. Jung, and T. N. Palmer (2011), On the predictability of the extreme sum-mer 2003 over Europe, Geophys. Res. Lett., 38, L05704, doi:10.1029/2010GL046455.

Cloke, H., Weisheimer, A., and Pappenberger, F. (2011) Representing uncertainty in land surface hydrology: fully coupled simulations with the ECMWF land surface scheme, ECMWF workshop on model uncertainty, Available at: http://www.ecmwf.int/staff/florian_pappenberger/publica-tions/pdf/Cloke.pdfSupervisors: Dr D Macleod and Dr A Weisheimer Email: Macleod@atm.ox.ac.uk

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Astrophysics projects

AS01 Measuring dark matter in galaxies

According to the currently standard scenario for galaxy formation, the Universe is dominated by a mysterious Dark matter component. Galaxies are expected to be surrounded by massive dark halos, which can be detected from their dynamical effects. In this project the student will “observe” existing state-of-the-art numerical simulations of galaxies and dark matter as if they were real galaxies. A Bayesian MCMC approach will allow him to test our ability to measure dark matter in galaxies using dynamical models.

Special skills: A basic knowledge of the Python program-ming language is required.Supervisor: Dr M Cappellari Email: cappellari@astro.ox.ac.uk

AS02 Star formation history of local galaxies

Understanding how and when galaxies form stars is a critical piece in our attempts to model galaxy formation and evolu-tion. This project uses a new code which applies Bayesian statisticstotheproblemoffittingstarformationhistoriestoobservational data from large surveys and the GalaxyZoo.org project. Questions which might be addressed include the question of whether bars promote or hinder star formation in disks (or both), the effect of mergers on the galaxy popula-tion or correlations between behaviour and the intergalactic environment. Some familiarity with Python will be useful. Supervisor: Dr C Lintott Email: cjl@astro.ox.ac.uk

AS03 Characterising Asteroids with Spectroscopy on the PWTPhilip Wetton Telescope

Asteroidsaretaxonomicallyclassifiedintodifferenttypesbased on the shape of their spectra. Most asteroids fall into three groups: C, S, and X; but there are about 20 other rarer groups.Around1500asteroidscurrentlyhaveclassifications(primarily from the SMASS survey in 2002). This is enough to understand the general population, but many asteroids remainunclassified.Thisprojectwillaimtousetwonewspectrographs on the Philip Wetton Telescope here in Oxford to classify previously unobserved asteroids.

The Philip Wetton Telescope (PWT) is a 40-cm telescope on the roof of the Denys Wilkinson building. It has a fairly advanced control system and set of instruments, meaning that even though it is relatively small, it can make interesting observations. We have recently added a spectrograph (de-veloped through previous MPhys projects) to the telescope, which provides the necessary capability to do this project. Theprojectwillbethefirstserioususeofthespectrographforscience.Assuch,someworkwillbeneededtorefinetheobservation and data reduction software.

The project will involve developing some (existing) software to select appropriate asteroids for observation; setting up the observationson thePWT; taking/monitoring theobserva-tions; developing a software technique to extract the spectra from the data; classifying the asteroid spectra.

Special Requirements

The project will require some night-time work with the tel-escope. Some familiarity with *nix computing, IRAF, and Python would be helpful, but not necessary.Supervisor: Dr F Clarke Email: fraser.clarke@physics.ox.ac.uk

AS04 Why do black holes launch relativistic jets

Supermassive black hole jets are the most powerful phe-nomena in the Universe. Rotating black holes cause inertial frames to rotate close to the event horizon and this twists andwarpsthemagneticfieldscontainedinthemagnetisedplasma accreting onto the black hole. This process transfers some of the enormous rotational energy of the black hole intomagneticenergy.Thetwistedfieldhasahuge,enhancedmagneticpressuresufficienttoacceleratenearbyplasmatoform jets moving close to the speed of light and travelling for hundreds of thousands of light years before colliding with the intergalactic medium forming spectacular shocks (google “images of Cygnus A”). These jets are the most luminous astrophysical objects, outshining their entire host galaxy. The precise mechanism that leads to the acceleration and collimation of these jets, however, is not well understood. The purpose of this project is to try to better understand the propertiesofthesejets,specifically:howthepowerofthejetdependson theblackhole rotationandmagneticfieldconfiguration; tocalculate thedynamicsandstructureus-ing analytic relativistic magnetohydrodynamic jet models.

This project is suitable for a mathematically able student, competentandinterestedinGeneralRelativityandfluiddy-namics. There is the potential for some computational work later in the project which would require basic programming skills in a language such as C. Interested students should contact me by email.Supervisor: Dr W Potter Email: Will.Potter@astro.ox.ac.uk

AS05 Multifield Inflation

Therapidexpansionoftheearlyuniverse,knownasinfla-tion, can be sourced by some as-yet unknown matter. Early modelspositedamassivescalarfield,the‘inflaton’asthesource. However, it has recently been shown that the sim-plest models are disfavoured by observations of the cosmic microwave background (Planck Collaboration 2015) which have placed bounds on the tensor-to-scalar ratio, a measure of the relative strengths of perturbative modes. Therefore thereisrenewedinterestininflationbroughtaboutbymorecomplicated matter models.

Questions to be addressed are: How does increasing the numberoffieldschange thedynamicsof inflation?Whatfield interactionsarecompatiblewithobservations?Doeschanging thematter source affect the likelihoodof infla-tion occurring? Some programming skill (MATLAB) will be required, and a knowledge of classical mechanics and simple cosmology.Supervisors: Dr D Sloan and Prof R Davies Email : davidjasloan@gmail.com

AS06 Finding Pulsars with Next Generation Tel-escopes

Over the last decade, pulsar searches have resulted in the discovery of new classes of Galactic radio emitting neutron stars and extremely bright isolated radio bursts from beyond our Galaxy. Discovery of these objects relies on fast and efficientsearchesofhugeamountsofdatarecordedattheworld’s largest radio telescopes. The next stage of searches in timedomainradioastronomyinvolvesmovingfromofflineprocessing of recorded data to online, streaming processing of data from new telescopes. The objective is to reach a fully real-time pulsar search with the Square Kilometre Array, a telescope that will have the sensitivity to discover much of the Galactic pulsar population. The pulsar search signal processing aims to reject spurious signals and increase the signal to noise ratio in the detections of pulsars, mainly taking advantage of their periodic nature. The project will aim to quantify the amount of signal recovery achieved by different signal processing pipelines and different algorithms used in time-domain radio astronomy. You will learn about cutting edge signal processing techniques in time-domain radio as-tronomy, how these are implemented and how to run codes that perform the signal processing tasks on synthetic data. Some familiarity with the Linux operating system would be advantageous. Work will be supported by pulsar group members from Astrophysics and the OeRC. Supervisor: Dr A Karastergiou Email: aris.karastergiou@gmail.com

AS07 Giant radio pulses from radio emitting neutron stars

Over the course of the last 2 years, we have been accumulat-ing data using the Low Frequency Array (LOFAR) to search for new pulsars and fast radio bursts. In the process, we have accumulated data from a handful of known, extremely bright pulsars. These pulsars are seen to occasionally emit extremely bright individual pulses, a phenomenon referred to typically as giant pulse emission. The low radio frequency data of LOFAR are particularly prone to propagation effects, as the radio signals travel through the magneto-ionised inter-stellar space. In this project, we will investigate individual pulses from this population of pulsars, with the aim of char-acterising the interstellar medium and the intrinsic properties of giant pulse emission. These investigations will shed light on the radio emission process of pulsars at low radio fre-quencies (150 MHz) and help understand potential extreme propagation events in the Galaxy. Work will be supported by pulsar group members from Astrophysics and the OeRC.Supervisor: Dr A Karastergiou Email: aris.karastergiou@gmail.com

AS08 Constraining Stellar Feedback with the Cir-cumgalactic Medium

Observations of galaxies and their environments show that energetic input from supernova and stellar winds (stellar feedback) plays a crucial role in their histories. Galaxies have beenlongthoughttobedeficientinbaryons,theso-called‘missing baryons’ problem; yet recent observations probing the halo environment surrounding galaxies, the circumga-lactic medium (CGM), show that perhaps as much as 80% of all metals produced by stars are later ejected from the galaxy and deposited into the CGM or beyond. Ejected along with these metals is a considerable fraction of the galactic gas, possibly solving the missing baryons. With this ejected material we may be able to constrain the nature of stellar feedback, a necessary step for advancing state-of-the-art cosmological simulations for comparison with precision cosmic observatories. In this project the student will explore theoretical models of enrichment of the CGM by stellar feedback, developing a model to compare with both observationsandsimulation.Proficientskillsintheoreticalmodels are key, and there is an opportunity to work with numerical simulations. Supervisor: Dr M Richardson Email: mark.richardson.work@gmail.com

AS09 also TP07 Stress-Tensor Induced Instabilities in Accretion Disks

In the classical theory of accretion discs, the form of the turbulent stress tensor is based on dimensional reasoning and taken to be directly proportional to the gas pressure. But if, as is now widely believed, the underlying causes of the turbulence are magnetohydrodynamic (MHD), the behaviour of the stress cannot possibly be so simple. For example, if the disk had no free electrons, MHD could not operate, so this alone would introduces a more complex dependence on density and temperature. In reality, physics of magnetised plasmas issufficientlyrich thateven inanamply ionisedgas the stress tensor depends on temperature and density in a manner much beyond a simple pressure scaling. This more complex behaviour can easily lead to dynamical instability for the disc, which is precisely what observations seem to demand for many compact X-ray sources. In this project, wewillidentifyspecificprocessesrelevanttodilute(weaklycollisional) as well as strongly collisional astrophysical plas-mas that affect the behaviour of the turbulent stress, propose simple (but not too simple!) models of the latter, investigate their stability properties, and try to relate them to observed state changes seen in X-ray sources.

Background Reading:

J. Frank, A. King and D. Raine, Accretion Power in Astro-physics (Cambridge U. Press, 2002)

J.-P. Lasota, “The disc instability model of dwarf novae and low-mass X-ray binary transients,” New Astron. Rev. 45, 449 (2001)

S. A. Balbus and P. Henri, “On the magnetic Prandtl number behavior of accretion disks,” Astrophys. J. 674, 408 (2008)

S. A. Balbus and P. Lesaffre, “The effects of Prandtl number onblackholeaccretionflows,”NewAstron.Rev.51,814(2008)

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A. A. Schekochihin, S. C. Cowley, F. Rincon and M. S. Rosin, “Magnetofluid dynamics ofmagnetized cosmic plasma:firehoseandgyrothermalinstabilities,”Mon.Not.R.Astron.Soc. 405, 291 (2010)

M. W. Kunz, A. A. Schekochihin, S. C. Cowley, J. J. Binney and J. S. Sanders, “A thermally stable heating mechanism for the intraclustermedium: turbulence,magnetic fieldsand plasma instabilities,” Mon. Not. R. Astron. Soc. 410, 2446 (2011)

M. W. Kunz, A. A. Schekochihin, S. C. Cowley, J. J. Binney and J. S. Sanders, “A thermally stable heating mechanism for the intraclustermedium: turbulence,magnetic fieldsand plasma instabilities,” Mon. Not. R. Astron. Soc. 410, 2446 (2011)Supervisors: Dr A Schekochihin (Theoretical Physics) and Prof S Balbus (Astrophysics)Email: a.schekochihin1@physics.ox.ac.uk, Steven.Balbus@astro.ox.ac.uk

AS10 Black-hole accretion and galaxy formation

One of the key issues in extragalactic astronomy is to determine the evolution of activity in the Universe. This activity is both in the form of accretion on to black holes and star-formation activity. Both of these active phenomena can be with observations at radio wavelengths. The aim of this project is to categorise the radio sources into different types of AGN and also the star-forming galaxies based on observations obtained with the Jansky VLA. After the radio sources have been categorized the student will then determine how the radio sources have evolved in their space density of cosmic time, and thus place important constraints on the impact of accretion activity on the evolution of galaxies.

For the second part of the project the student will need to do some programming to determine the evolution of the radio luminosity function.Supervisor: Dr M Jarvis Email: Matt.Jarvis@astro.ox.ac.uk

AS12 Finding the most distant galaxies with the VISTA-VIDEO Survey

VIDEO is the deepest near-infrared survey covering over 10 square degrees on the sky. In this project the student will identify the rare objects at redshifts z>6 in the VIDEO survey by using the deep multi-band imaging that is available. On findingsuchsourcesthestudentwillworkondeterminingtheselection function of such sources and hence determine their number density. The aim of the project will be to determine whether the number of these massive galaxies at the high-est redshifts are expected from latest generation of galaxy formation models, and if not then why not.

The student will need some competence in computer pro-gramming.Supervisor: Dr M Jarvis Email: Matt.Jarvis@astro.ox.ac.uk

AS13 Dynamics of extrasolar planets

More than 1000 extrasolar planets around main sequence stars have been detected since the discovery of the very firstin1995.Mostoftheseobjectswereobservedthroughradial velocity measurements, i.e. through the Doppler shift of the stellar lines induced by the motion of the star around theplanet/starsystemcentreofmass.Thismethodenablesthe calculation of the parameters of the planet orbit (period, semimajor axis, eccentricity...) and of the planet mass pro-jected onto the line of sight.

Asignificantnumberoftheplanetsdetectedsofararefoundto move along an orbit which is in a plane that does not coincide with the equatorial plane of the host star. This is difficulttounderstandwithinthecontextofthecommonlyaccepted planet formation scenario, in which planets as-semble in a disc in the stellar equatorial plane, and there is currently no theoretical modelling that accounts for this observational fact.

This project aims at exploring a model in which the mis-aligned planets have formed out of the disc through a frag-mentation process occurring in the protostellar envelope while it collapses onto the forming star. In this context, the misaligned planets interact with the disc and which each other. Given a population of planets formed that way, we will calculate the characteristics of the orbits after the system has relaxed and the disc has dissipated. This project will make use of a N-body code that computes the trajectory of the planets under the various relevant forces. The work will be both numerical and analytical. Supervisor: Dr C Terquem Email: Caroline.Terquem@astro.ox.ac.uk

AS14 High-redshift disk formation

Although unobserved as yet, galaxies in their infancy about 500 million years after the Big Bang are already being simu-lated by computational cosmologists. These early galaxies are predicted to form at the intersections of the cosmic web that grows out of the seed perturbations imprinted after the Big Bang. This project will study how gas streaming alongfilamentsinthecosmicwebcanformrapidlyrotat-ing, dense, gaseous disks at their intersections in the high redshift Universe. In the simulations, these gaseous disks appear to be rotating as fast as the Milky Way but they are about a tenth of its size. Under such extreme conditions, a disk can become gravitationally unstable and fragment into massive gas “clumps” which could collapse into star clusters. Therefore understanding how these high redshift galaxies acquire their rapid rotation is crucial to making sense of high-redshift star formation.

The goal of this project, is to explain these rapidly rotat-ing, small disks. This will involve converting outputs from ultra-high resolution hydrodynamical cosmological simula-tions into a format that is readable by a sophisticated three-dimensional visualization software, and then measuring the orientationofthefilamentsrelativetothedisk.Fromthegeo-metrical information, and measurements of the gas velocities inthefilaments,anexplanationforthediskorientationandextreme rotational disk velocities will be constructed.

Good programming skills required.Supervisors: Dr A Slyz and Dr J Devriendt Email: slyz@astro.ox.ac.uk; jeg@astro.ox.ac.uk

AS15 Observations of W Ursa Majoris Variables in NGC 188 with the Philip Wetton Telescope

W Ursa Majoris variables are binaries where the two stars are almost in contact. Light curves and periods are known to show changes over time.

The Philip Wetton Telescope will be used to obtain light curves of W Ursa Majoris variables in the old open cluster NGC 188; these will be compared with earlier data obtained in Oxford and published in the literature.

Recommended Reading:

Li L, Han Z & Zhang F, 2004 MNRAS 351, 137 Zhang XB, Deng L, Zhou X & Xin Y, 2004 MNRAS 355, 1369 Supervisor: Dr A E Lynas-Gray Email: aelg@astro.ox.ac.uk

AS16 tbc

More details from the supervisor.Supervisor: Dr R Simpson Email: Robert.Simpson@astro.ox.ac.uk

AS17 Measurement methods for weak gravitational lensing

The clumpy distribution of dark matter in the universe causes gravitational lensing of distant galaxies, which may be measured from the statistical distortion of galaxy shapes that results. So-called “weak lensing surveys” aim to measure this effect to high accuracy and use it to constrain cosmological models. The European Space Agency is launching the Euclid mission around 2020 to measure it with unprecedented ac-curacy. However, all current measurement methods suffer from bias. The aim of this project is to develop and test new methods of making the measurements in a bias-free way, as preparation for Euclid. Skills at handling datasets and programming would be useful for this project.Supervisor: Prof L Miller Email: l.miller@physics.ox.ac.uk

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Biological Physics projects

BIO01 Digital holographic microscopy for 3D tracking of bacterial swimming

The aim of the project is to construct a digital holographic microscope that is able to track, in 3 dimensions, small objects like swimming bacteria or microspheres that are markersofflowfields.

A hologram is a 2-dimensional image of the pattern formed by interference between the light scattered by an object and a coherent reference beam of known phase. A hologram records the phase of the object beam relative to the reference beam, which allows reconstruction of the object beam - and therefore a 3-dimensional image of the object. Traditional hologramsarerecordedonphotographicfilm,andtheob-ject beam is reconstructed via diffraction of a copy of the reference beam by the hologram. With modern cameras, holograms can be recorded digitally at video rates, and the object beam reconstructed numerically using high-speed computing, generating 3-dimensional videos.

The student will have the choice of two distinct holographic configurations,eitherin-line(onlytheamplitudeofthescat-tered light is used in a reconstruction) or off-axis (the phase of the scattered light is also recovered before a reconstruction). All the required computer programmes are already written. After the microscope is built, the student will use it to track swimmingbacteriaanddiffusingparticles,and/ortomeasuretheflowfieldsaroundswimmingandfallingobjects.

Requirement: Some familiarity with optics and computer programmingwouldbeuseful,butnospecificpriorexperi-ence is necessary. Please contact the supervisor if you are interested in the projectSupervisor: Dr R Berry Email: r.berry@physics.ox.ac.uk

BIO02 & 03 DNA Nanostructures

DNA is a wonderful material for nanometre-scale fabri-cation. Short lengths of DNA can be designed such that Watson-Crick hybridization between complementary sec-tions leads to the self-assembly of complex nanostructures. Nanostructures can be used to deliver a payload into a cell, as a scaffold for protein crystallography or as both track and motor components of a molecular assembly line. The project will involve design, fabrication and characterization of a DNA nanostructure.Supervisor: Prof A Turberfield Email: a.turberfield@physics.ox.ac.uk

BIO04 Structure/function studies of ion channels

The project will involve determining the relationship be-tween the structure and function of a number of different ion channels found in the membranes of living cells which control cellular electrical excitability. We principally study K+ ion channels using a combination of molecular biology, protein biochemistry and electrophysiology.

Requirement: Although no previous experience is required, some interest in biological systems is essential as there will be a certain amount of background reading required.Supervisor: Dr S Tucker Email: s.tucker@physics.ox.ac.uk

BIO05 Super-resolution optical STED microscopy

Studies of complex biological systems such as of living cells demand the use of non-invasive and very sensitive analysis techniquessuchas(far-field)opticalfluorescencemicros-copy. Its only drawback is the limited spatial resolution: the diffraction of light prevents that objects closer than about 200 nm can be discerned. As a consequence, important details of for example the organization and interaction dynamics of proteins and lipids in the cellular membranes cannot be dis-closed. Remedies to this physical limit are recently developed super-resolution microscopy or nanoscopy techniques such as stimulated emission depletion (STED) microscopy. With STED, details of cellular structures and protein aggregations can be imaged and analysed with much larger details, and when combined with single-molecule detection it allows the disclosure of complex dynamical processes otherwise impeded by the limited spatial resolution of conventional far-fieldmicroscopy.Thisprojectwillinvolvefurtherdevel-opment of such as STED microscope to be able to simultane-ously observe different molecules with down to 40nm spatial resolution. It will involve hardware and software work, as well as introduction into working with cells.Supervisors: Dr C Eggeling and Dr A Kapanidis Weatherall Institute of Molecular Medicine, University of Oxford E-mail: christian.eggeling@rdm.ox.ac.uk

BIO06 DNA biosensors

Transcription factors are proteins that control gene expres-sion; they act as robust natural biosensors and switches, receiving chemical and physical signals from the cellular environment and regulating the copying of DNA to mes-senger RNA. A remarkable variety of signals modulate transcription-factor activity, including temperature shifts, light exposure, levels of biochemicals (such as sugars, met-als, and hormones), population density and oxidative status. Due to their central role in gene expression, transcription factors can serve as indicators of disease and other physi-ological conditions. We recently developed DNA biosensors for ultra-sensitive detection of transcription factors and their signals using single-molecule spectroscopy.

Potential projects in this area include design of improved DNA biosensors for existing transcription factors; develop-ing novel biosensors to detect different stimuli; and real-time biosensing in living cells (using single-molecule imaging or fluorescencecorrelationspectroscopy).Nospecialskillorprior knowledge or experience of biophysics is necessary. Introductory literature will be provided.Supervisor: Dr A Kapanidis Email: a.kapanidis@physics.ox.ac.uk

BIO07 tbcMore details from the supervisor.Supervisor: Dr S Contera Email: s.antoranzcontera1@physics.ox.ac.uk

Condensed Matter Physics projects

CMP01 Single photon sources in the blue – quantum dot physics

A single photon source (SPS) is a light source that, on de-mand, or at a known repetition rate, produces exactly one photoninadefinitequantumstate.Theearliestsourcesofsingle photons were very heavily attenuated pulsed lasers or other classical sources, for which the photon count distribu-tion is Poissonian, so that the probability of the emission of two photons simultaneously is never zero. A genuine, on-demand SPS could employ a single quantum emitter, which cannot emit more than one photon at a time. Single molecules and single atoms have been used in this way, but such systems must be optically driven, and are often highly complex. An electrically driven source, based on a single QD has much to offer in terms of simplicity and practical-ity. Many applications in quantum information processing (QIP) depend critically on SPSs – most notably quantum cryptography and linear optical quantum computation, where for protocols based on polarization encoding, it is desirable to have a single-photon source whose output has afixedpolarizationdependingonthegeometryorstructureof the emitter.

In this project the student will join my research group to work on microphotoluminescence spectroscopy of semicon-ducting nitride quantum dots, which span a wide range of bandgaps from 0.7 eV (InN) to 6.2 eV (AlN) and present spe-cificadvantagesandopportunitiesintheproductionofSPSs.The nitrides open up the blue and ultra-violet spectral region which is particularly relevant to satellite-based free space quantum key distribution (QKD), since the weight-limited telescopes required for this application have the lowest beam divergence at blue or near ultra-violet (UV) wavelengths. Furthermore, ultra-fast detectors which require only Peltier cooling are available in the blue-green spectral region, but notatlongerwavelengths,providingasignificantpracticaladvantage for the nitrides in both laboratory development of QIP and target applications in QKD. The large available band offsets between the different nitride alloys can provide a large barrier to carrier escape from the QD, improving the temperature stability of the SPS. Nitride semiconductors have a wurtzite crystal structure in which the lack of a centre of symmetry results in very large piezo-electric constants. Hence, strained QDs grown on the polar c-plane have large internal electricfields,whichmaybemanipulatedby anexternalelectricfield,tuningtheQDemissionwavelengthover 60 meV or more, a degree of tuning which has yet to be achieved in the conventional III-V materials.

The student will work with a range of laser-based spec-troscopic techniques, including microphotoluminescence spectroscopy, cryogenic work, time-resolved spectroscopy and the use of SEMs and e-beams.Supervisor: Prof R Taylor Email: r.taylor@physics.ox.ac.uk

CMP02 Investigating the physics of coupled magnonic resonators at millikelvin temperatures

Thefieldofmagnonicsistheareaofmagneticsdedicatedto the science of quasi- particles known as magnons. In cer-tain magnetic systems, magnons are able to play the role of microscopic tokens which can carry ‘spin’ — the quantum mechanical currency of magnetism — over relatively long distances (up to centimetres), and at high speed (many tens of kilometres per second). Our group develops low-temperature microwave magnetic circuits to probe the physics of mag-nonic systems at the quantum level.

This project will involve designing and carrying out an experiment in which microwave- frequency magnon modes in two lumped magnetic samples are controllably coupled. Measurements will be made in a dilution refrigerator. The work will contribute to our group’s investigations into how magnons — the quasi- particles associated with excitations of the electronic spin- lattices of ferro- and ferrimagnetically ordered materials — might be used in new types of quantum measurement and information processing device. This is a project suitable for anyone who enjoys challenging practical work and has a strong interest in magnetic dynamics and low- temperature experimental techniques. Supervisor: Dr A Karenowska Email: A.Karenowska@physics.ox.ac.uk

CMP03 Investigating magnon propagation in magnetic waveguides at millikelvin temperatures

Thefieldofmagnonicsistheareaofmagneticsdedicatedto the science of quasi- particles known as magnons. In cer-tain magnetic systems, magnons are able to play the role of microscopic tokens which can carry ‘spin’ — the quantum mechanical currency of magnetism — over relatively long distances (up to centimetres), and at high speed (many tens of kilometres per second). Our group develops low- temperature microwave magnetic circuits to probe the physics of mag-nonic systems at the quantum level.

This project will involve designing and carrying out experi-ments in which propagating microwave- frequency magnon modes are excited and detected in a magnonic waveguide. Measurements will be made in a dilution refrigerator. The work will contribute to our group’s investigations into how magnons — the quasi- particles associated with excitations of the electronic spin- lattices of ferro- and ferrimagnetically ordered materials — might be used in new types of quantum measurement and information processing device. This is a project suitable for anyone who enjoys challenging practical work and has a strong interest in magnetic dynamics and low- temperature experimental techniques. Supervisor: Dr A Karenowska Email: A.Karenowska@physics.ox.ac.uk

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CMP04 Investigating the spin pumping and inverse spin Hall effects at low temperatures

Thefieldofmagnonicsistheareaofmagneticsdedicatedto the science of quasi- particles known as magnons. In cer-tain magnetic systems, magnons are able to play the role of microscopic tokens which can carry ‘spin’ — the quantum mechanical currency of magnetism — over relatively long distances (up to centimetres), and at high speed (many tens of kilometres per second). Our group develops low- temperature microwave magnetic circuits to probe the physics of mag-nonic systems at the quantum level.

This project will involve designing and carrying out a low- temperature experiment to make an inverse spin Hall effect based measurement of a magnon- driven spin current pumped throughamagneticinsulator/non-magneticmetalinterface.Measurements will be made in a dilution refrigerator. The work will contribute to our group’s investigations into how magnons — the quasi- particles associated with excitations of the electronic spin- lattices of ferro- and ferrimagnetically ordered materials — might be used in new types of quantum measurement and information processing device. This is a project suitable for anyone who enjoys challenging practical work and has a strong interest in magnetic dynamics and low- temperature experimental techniques. Supervisor: Dr A Karenowska Email: A.Karenowska@physics.ox.ac.uk

CMP05 Simulations of Solid State Matter Compressed to Planetary Interior Conditions

The highest pressure solids that can be produced on Earth have conventionally been created by squeezing matter between two diamond anvils - a method that works well until the anvils break. Unfortunately, this happens at a few Mbar - about the pressure at the centre of the Earth. To get to much higher pressures, we must use dynamic techniques - such as evaporating the surface of a solid sample with a high power laser, and allowing the plasma to expand into the vacuum. The rest of the target feels a force (via New-ton’s third law), and is slowly compressed to tens of Mbar, and it is believed that pressures close to that at the centre of Jupiter (70 Mbar) can be obtained by this method. The trick is to keep the material close to an isentrope, and to stop the compression wave forming a shock (which will melt the sample). In this project the student will undertake hydrodynamic and multi-million atom molecular dynamics simulations of both shock and ramped-compressed targets to identify the isentropic and heating regions. Interestingly, the ‘slow’ compression associated with an isentrope can be as rapid as a few hundred picoseconds.

Reading

Higginbotham et al, Phys. Rev. B 85, 024112 (2012)Supervisors: Prof J Wark and Dr M Suggit Email: J.Wark1@physics.ox.ac.uk, m.suggit1@physics.ox.ac.uk

CMP06 Quantum properties of implanted muons

Muons implanted into materials can be used to measure local microscopicfields[1].Thistheoreticalandcomputationalproject will employ quantum-mechanical calculations using density matrices [2] to evaluate the spin dynamics of muons in various model situations (see [3],[4] for recent examples).

Background reading:

[1] S. J. Blundell, Contemporary Physics 40, 175 (1999).

[2] M. Celio and P. F. Meier, Phys. Rev. B 27, 1908 (1983).

[3] J. S. Möller, D. Ceresoli, T. Lancaster, N. Marzari and S. J. Blundell, Phys. Rev. B 87, 121108(R) (2013).

[4] F. R. Foronda, F. Lang, J. S. Möller, T. Lancaster, A. T. Boothroyd, F. L. Pratt, S. R. Giblin, D. Prabhakaran and S. J. Blundell, Phys. Rev. Lett. 114, 017602 (2015).Supervisor: Prof S Blundell Email: s.blundell@physics.ox.ac.uk

CMP07 Calculation of the magnetic properties of mo-lecular magnets

New molecular magnets have been prepared which consist of chains of magnetic ions linked by organic groups and single molecule magnets in which the magnetic ions are embedded within single molecules [1]. The magnetic properties of such systems will be calculated using statistical mechanical techniques with the aim of exploiting the symmetry inherent in these systems [2].

Background reading:

[1] S. J. Blundell and F. L. Pratt, J. Phys.: Condens. Matter 16, R771 (2004).

[2] R. Schnalle and J. Schnack, Phys. Rev. B 79, 104419 (2009). Supervisor: Prof S Blundell Email: s.blundell@physics.ox.ac.uk

CMP08 Micromagnetism of Thin Film Structures and Devices

Magnetic multilayers are at the heart of modern computing, with effects such as giant magnetoresistance (which won the Nobel Prize in 2007) being integral to the continued growth of computer power. A new generation of devices aims to achieve ultrafast write operations through the use of the spin transfer torque, realising a low-power high-stability memory scheme.

Ferromagnetic resonance (FMR) uses microwaves to stimu-lateprecessionofmagnetisationinthinfilms,allowingeasydetermination of materials parameters such as anisotropy constants and damping factors. This project will involve modelling of such experiments in NIST’s Object Oriented Micromagnetic Framework (OOMMF), with the aim of in-vestigating dynamic exchange coupling in multilayers. The effects of non-uniform strain, antisymmetric excitations and the introduction of non-magnetic spacers will be studied. The student will also be involved in the growth by molecular beamepitaxyofsuchfilms,theirinitialfindingswillinformgrowths to be conducted later on in the project. Simulations will be conducted in parallel to experimental measurements performed by the Magnetic Spectroscopy Group at Diamond Light Source, the UK’s national synchrotron. There will be opportunities to work in this lab and perform vector-network analyser FMR measurements using the group’s octupole magnet system.

Students interested in this project are encouraged to contact Alex Baker (alexander.baker@physics.ox.ac.uk) for further information and to discuss any questions they may have.

Further Reading

[1] Baker, AA et al, “Modelling Ferromagnetic Resonance in Magnetic Multilayers: Exchange Coupling and Demagneti-sation-Driven Effects” Journal of Applied Physics.

[2] Donahue, MJ and Porter, DG “OOMMF User’s Guide, Version 1.0” NIST inter-agency report

[3] Kradasz, M et al “Ferromagnetic resonance studies of accumulation and diffusion of spin momentum density in Fe/Ag/Fe/GaAs(001)andAg/Fe/GaAs(001)structures”PRB

[4] Herman & Sitter, “Molecular Beam Epitaxy”, Springer-Verlag

Special skills required:

As a simulation project an interest in computing and pro-gramming, particularly in Python, would be advantageous. Experience of OOMMF and micromagnetics is NOT re-quired.Supervisor: Dr T Hesjedal Email: t.hesjedal1@physics.ox.ac.uk

CMP09 Growth and transport studies of topological insulator nanomaterials

Topological insulators are a very exciting new class of quantum materials that is insulating in its bulk and con-ducting on its surface. The exotic metallic surface state is topologically protected by time-reversal symmetry against a number of scattering effects. As a result, the novel phases of matter that have been known since the discovery of the fractional quantum Hall effect seem now to be in reach for room-temperature spintronic and quantum computing device applications.

Recently, we have shown that TI nanostructures can be grown using a novel catalyst which does not leave traces of itself in the growing nanostructure. This project builds on these recent breakthroughs by systematically studying binary and ternary catalyst systems with the aim of achieving selected area growth, particularly through the manipulation of the chemical binding agent.

This exploratory materials synthesis project uses chemi-cal vapour deposition (CVD) and molecular beam epitaxy (MBE) for the materials synthesis. MBE is a superior tool for the precise engineering of quantum materials – in the formofthinfilms,nanowires,orself-assembledquantumdots. For the characterisation of the materials, scanning electronmicroscopy(SEMw/EDS),transmissionelectronmicroscopy (TEM), atomic force microscopy (AFM), x-ray diffractionandreflectometry(XRD/XRR)willbeapplied.Magnetotransport measurements will be carried out in a PPMS system on contacted nanostructures. The work will be carried out in Oxford’s Thin Film Quantum Materials LaboratoryintheRCaH(http://www.rc-harwell.ac.uk/)attheRutherford Appleton Laboratory and in the Clarendon Lab.

Reading list:

1. M. König, S. Wiedmann, C. Brüne, A. Roth, H. Buhmann, L. W. Molenkamp, X.-L. Qi, and S.-C. Zhang, “Quantum Spin Hall Insulator State in HgTe Quantum Wells”, Science 318, 766, (2007)

2. D. Kong, J. C. Randel, H. Peng, J. J. Cha, S. Meister, K. Lai, Y. Chen, Z.-X. Shen, H. C. Manoharan, and Y. Cui,

“Topological Insulator Nanowires and Nanoribbons”, Nano Letters, Vol. 10, 1, 329, (2010)

3. P. Schoenherr et al. - please contact piet.schoenherr@physics.ox.ac.ukfor preprints.

Required skills: practical lab experience, strong interest in materials, strong work ethics. Desired skills: electron microscopy; scanning probe microscopy; ultra-high vacuum technology a plus, but not a must; basic knowledge of elec-tronics and programming (e.g. Python)Supervisor: Dr T Hesjedal Email: t.hesjedal1@physics.ox.ac.uk

CMP10 De-twinned single crystals: preparation and properties

Topological insulators represent a new form of quantum mattSingle crystals are a very special form of matter, having crystalline perfection in all directions. In reality, however, many single crystals contain defects which reduce their usefulness in fundamental studies and technological applica-tions. A common form of defect is called “twinning”. This occurs when the crystal undergoes a symmetry-breaking phase transition which results in two or more equivalent structural domains related by symmetry. One way to re-move twinning defects is to apply pressure to the crystal at elevated temperatures and then cool the crystal through the phase transition.

In this project you will re-assemble a de-twinning apparatus in the Clarendon Laboratory, and develop a user interface to control pressure and temperature in the apparatus, and to record images from a microscope. Once the apparatus is operational it will be applied to de-twin a number of dif-ferent magnetic crystals of interest and, if time permits, the de-twinned crystals will be studied with x-ray diffraction and magnetic and transport measurements. Supervisors: Dr D Prabhakaran, Prof A Boothroyd Email: d.prabhakaran@physics.ox.ac.uk,a.boothroyd@physics.ox.ac.uk

CMP11 Preparation and characterisation of ferromag-netic topological insulators

Topological insulators represent a new form of quantum mat-ter which is insulating in the bulk but has a metallic surface which is protected by a topological feature in the electron bands. When topological insulators are placed in proximity to other materials, exotic and interesting phenomena are predicted to emerge which could have practical uses. One way to achieve this is to introduce magnetic order into a topological insulator, which leads to a breaking of time reversal symmetry.

In this project you will prepare single crystals of the topo-logical insulator Bi2Se3 combined with the ferromagnetic material Fe7Se8 in different ratios. The aim is to obtain a topological insulator which is ferromagnetic at room tem-perature, and to explore its properties. The crystals will be characterised by a range of techniques including X-ray dif-fraction, magnetic measurements, and electrical and thermal transport. The project is experimental and is a mix of materi-als preparation and physical measurements.Supervisors: Dr D Prabhakaran, Prof A Boothroyd Email: d.prabhakaran@physics.ox.ac.uk,

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a.boothroyd@physics.ox.ac.uk

CMP12 External quantum efficiency of Perovskite solar cells

Research into organic-inorganic Perovskite materials for solar cell applications is currently an extremely active area ofresearch.Injustafewyearspowerconversionefficien-cies of these solar cells have jumped from a few percent to ~20%. In this project you will use and further develop a new Fourier method of determining the external quantum efficiency(EQE)spectrumofstate-of-the-artvapourdepos-ited Perovskite solar cells. The project will involve device physics, instrumentation and programming for data analysis. The project is best suited for someone who would like to continue research in experimental physics.

Further reading: see Nature, 501:395 and

https://www-thz.physics.ox.ac.uk/perovskites.htmlSupervisors: Dr M Johnston and Prof L Herz Email: m.johnston1@physics.ox.ac.uk, L.Herz1@physics.ox.ac.uk

CMP13 Non-contact temperature sensing

Non-contact temperature sensing is becoming increasingly being used in many areas including medicine and motion sensing. In this project you will interface a commercial thermopile array (Omron D6T) with a Raspberry Pi computer using the i2C protocol, and create a user interface. You will test and characterise your instrument using laboratory-based far and mid infrared radiation sources, including a terahertz time-domain spectrometer. Finally the optics of the sensor willbemodifiedandrotation/translationstagesintroducedto allow the instrument to map the surface temperature dis-tribution of objects. This project is best suited to someone who has good programming skills and is keen to innovate and extend the project. Supervisors: Dr M Johnston and Prof L Herz Email: m.johnston1@physics.ox.ac.uk, L.Herz1@physics.ox.ac.uk

CMP14 Optical Optimisation of Multi-junction Solar Cells

The aim of this project is to develop a new computational tool that will support the optimisation of multi-junction solar cells. The tool will be based on the transfer matrix approach describing the absorption, reflection and transmission inmultilayer stacks of known optical constants and need to take into account some knowledge about the solar cells that are combined into the multi-junction solar cells. Whereas the optimisation of single-junction solar cells does only involve a few layers and manual optimisation of the layer order and thickness is still possible, multi-junction solar cells show so many free parameters and constraints that make a manual optimisation nearly impossible.

The project is of high relevance for the optimisation of next generation of solar cells that combine photovoltaic active materials that absorb in (ideally) different wavelength ranges in multi-junction solar cells. The employed layers are usu-ally thinner than the coherence length of sun light. Hence, interference effects play an important role in the order and thickness of the absorbing and transparent spacer layers. The

tool will have direct practical relevance for the research in the Clarendon and the solar cells developed there, because its results will be the basis for the fabrication of multi-junction solar cells.

The student should have a strong interest in solid state phys-ics, coupled with a good knowledge of linear algebra and optimisation routines. A good coding ability is essential, and the student will be required to use Python or C++.Supervisor : Dr M Riede Email : moritz.riede@physics.ox.ac.uk

CMP15 Surface acoustic wave resonators in the quan-tum regime

Surface acoustic wave (SAW) devices on piezoelectric crys-tals are widely used in electronic engineering for a variety of applicationssuchasoscillatorsandfilters.Wehaverecentlybegun to take such devices towards the quantum regime, by making very high quality SAW circuits from superconduc-tors and cooling them to millikelvin temperatures. This project will involve designing, measuring and understanding a new range of SAW devices fabricated from different types of piezoelectric crystal, and up to GHz frequencies, in a bid to truly reach the quantum ground state in such a device forthefirsttime.Itmayalsobepossiblewithintheprojectto couple a SAW resonator to a superconducting qubit for afirstdemonstrationofthestronginteractionofthequbitwith single SAW phonons.Supervisor: Dr P J Leek Email: peter.leek@physics.ox.ac.uk

CMP16 Superconducting qubits in microwave cavities

Superconducting electric circuits are proving to be a strong candidate for building theworld’s first useful universalquantum computer within the next decade. We are looking at ways to couple superconducting qubits together in lattices using microwave cavities. This project will involve design-ing, simulating, making and measuring specially designed superconducting cavities to enable this networking, and studying the coherence of superconducting qubits contained in them. The project may also involve integration of local qubit control circuitry and operation of quantum logic gates.Supervisor: Dr P J Leek Email: peter.leek@physics.ox.ac.uk

CMP17 Hybrid solid state cavity QED

Cavity QED involves enhancing the interaction strength between atoms and light by confinement inside a cavity.This enables the study of the coherent exchange of energy between the systems, and of a very wide range of interesting phenomena in quantum optics. We are studying new forms of cavity QED in solid state devices in which interesting new quantum systems are accessed and controlled by coupling them to either electromagnetic or acoustic cavities. This ena-bles the systems to be well isolated from their environment and studied in or close to their ground state. This project will involve investigating cavity QED physics in novel carbon nanotube or electron spin ensemble based devices, depending on the evolution of our work on the topics over the next 6 months.Supervisor: Dr P J Leek Email: peter.leek@physics.ox.ac.uk

CMP18 Electronic structure of novel superconducting materials

In 2008 a new class of superconductors containing iron has been discovered which has generated a surge of activity in understanding the origin of superconductivity in these materials. Iron is one of the most unexpected elements found in a superconductor due to its strong ferromagnetic properties which is often found detrimental to sustaining a superconducting state. One of the important aspects for understanding the superconductivity in these iron pnictides is to test their electronic behaviour, as their superconductivity emerges from a bad metallic and magnetic state.

This project aims to predict the electronic properties of new candidate superconductors mainly computationally in order to reveal the relevance of altering the structural arrangements on the superconducting properties. A suitable candidate for this project should have good knowledge of condensed mat-ter courses and strong computation skills would be valuable to the project.

For further questions please email amalia.coldea@physics.ox.ac.uk

For further reading use:

Indirect evidence for strong coupling superconductivity in FeSeunderpressurefromfirst-principlecalculations

Nature Physics 6, 645–658 (2010)

Phys. Rev. Lett. 101, 216402 (2008)

Phys. Rev. Lett. 103 103, 026404 (2009)

Other useful links:

Wien2k allows electronic structure calculations of solids using density functional theory (DFT); BoltzTrap is a pro-gramforcalculatingthesemi-classictransportcoefficients.Supervisor: Dr A Coldea Email: a.coldea@physics.ox.ac.uk

CMP19 Exploring the electronic properties of the topo-logical Dirac materials

Topological insulators are electronic materials with strong spin-orbit interaction that have insulating bulk properties and topologically protected metallic surfaces on their surfaces or edges. In ordinary materials, backscattering, in which electrons take a turn back owing to collisions with crystal defects,effectivelydegradesthecurrentflowandincreasesthe resistance. On the surface of topological insulators, back-scattering processes are completely suppressed (forbidden), so charge transport is in a low-dissipation state with excep-tional transport mobility and reduced energy consumption, which due to their long life and low maintenance costs are extremely attractive for semiconductor devices.

The superconductivity found in certain candidate topological insulatorsispredictedtohaveasignificanteffectonunder-stand fundamental physics in particular in the search for Majorana fermions as well as from the applications point of view to pave the way towards designing novel dissipation-less devices.

This project aims to explore the electronic properties of candidate topological insulators both experimentally and computationally. Measurements will be performed at low

temperatures using liquid helium and in certain cases also highmagneticfields.Theprojectwillusealsobandstructurecalculations to understand the electronic properties of these materials. A suitable candidate for this project should have good knowledge of condensed matter courses as well as computational and practical skills.

For further questions please email amalia.coldea@physics.ox.ac.uk

For further reading please consult:

Topological insulators and superconductors,

Rev.Mod.Phys.83,1057-1110(2011)orhttp://arxiv.org/abs/1008.2026

Read also

Observation of a topological 3D Dirac semimetal phase in high-mobility Cd3As2 and related materials

http://arxiv.org/abs/1211.6769

Other useful links:

Wien2k allows electronic structure calculations of solids using density functional theory (DFT); BoltzTrap is a pro-gramforcalculatingthesemi-classictransportcoefficients.Supervisor: Dr A Coldea Email: a.coldea@physics.ox.ac.uk

CMP20 Torque magnetometry of novel superconduc-tors

In 2008 a new class of superconductors containing iron has been discovered which has generated a surge of activity in understanding the origin of superconductivity in these materials. Iron is one of the most unexpected elements found in a superconductor due to its strong ferromagnetic properties which is often found detrimental to sustaining a superconducting state. One of the important aspects for understanding the superconductivity in these iron pnictides is to test the properties of the superconducting state and how it emerges from a bad metallic and magnetic state.

This project aims to explore experimentally the supercon-ducting properties of candidate iron-based superconductors. Measurements will be performed at low temperatures us-ingliquidheliumandinhighmagneticfields.Theprojectwill require the calibration of the torque measurements in absolute units. A suitable candidate for this project should have good knowledge of condensed matter courses as well as strong computational and practical skills.

For further questions please email amalia.coldea@physics.ox.ac.uk

For further reading please consult:

Anisotropyof superconductingsinglecrystalSmFeAsO_(0.8)F_(0.2)studiedby torquemagnetometryhttp://arxiv.org/abs/0806.1024

Torque magnetometry on single-crystal high temperature superconductors near the critical temperature: a scaling ap-proachhttp://arxiv.org/abs/cond-mat/9912052

Torque magnetometry in unconventional superconductors https://www.princeton.edu/physics/graduate-program/the-ses/theses-from-20...Supervisor: Dr A Coldea Email: a.coldea@physics.ox.ac.uk

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CMP21 Photoluminescence from organo metal halide perovskites

Recently a new family of semiconducting material, the organometal halide perovskites, has been generating a huge amount of interest as a candidate for high performance next generation solar cells, able to deliver low cost renewable energy on a large scale. However, these materials are still at an early stage of development and their performance has not yet been optimised.

Thisprojectwillusephotoluminescencequantumefficiency(PLQE) and time-resolved photoluminescence spectroscopy to investigate the dynamics of the charge carriers in the perovskite. This will include the study of various surface treatments and their impact on charge lifetimes, thermal stability and solar cell device performance. The project will encompass several types of new and exciting perovskite materials, which are already showing promising solar cell deviceresults.Specificdetailsoftheinvestigationmaybediscussed with the supervisor.

This is an experimental project, predominantly working with lasers using photoluminescence spectroscopy techniques. There could also be the opportunity to prepare samples in the laboratory, write Matlab code to analyse data and to use physical models to determine properties of the material, depending on the interests of the student and the develop-ment of the project.Supervisor: Dr H Snaith Email: h.snaith1@physics.ox.ac.uk

CMP22 Specific heat measurements of quantum mag-nets in applied field and at low temperatures

This project is to work in the quantum magnetism group in the Clarendon Laboratory to improve and extend the cur-rent experimental capabilities to measure the heat capacity (specific heat) of single crystalmagneticmaterials downto low temperatures and in appliedmagneticfields.Heatcapacity is a very sensitive probe to detect thermodynamic signatures of structural and magnetic phase transitions. This project is optimise the performance of an existing design for a measurement platform onto which the sample, resistive heater and thermometer sensors will be mounted and inter-faced with measurement equipment that monitors how the sample temperature changes upon passing a known electric current through the heater. This setup will be cooled inside acryostatwheremagneticfieldscanalsobeapplied.Wewould like to expand the capabilities of the system to include the option to measure the magnetocaloric effect (variation of sample temperature upon sweeping themagneticfielddue to changes in entropy upon crossing phase boundaries). Thiswillrequiremodificationstoboththehardware(add-ing new components) and software (changes to the control software). This experimental setup will be used to measure novel materials of current research interest synthesized in the Clarendon Laboratory, such as quantum magnets with novel ordered phases at low temperatures and in high applied magneticfields.

This project would be suitable for a student with a keen interest in practical, hands-on experimental work, who is taking the C3 CMP option.

Useful reference:

High-resolutionalternating-fieldtechniquetodeterminethemagnetocaloric effect of metals down to very low tempera-tures, Y. Tokiwa and P. Gegenwart, Rev. Sci. Instrum. 82, 013905 (2011).

http://rsi.aip.org/resource/1/rsinak/v82/i1/p013905_s1Supervisor: Dr R ColdeaEmail: r.coldea@physics.ox.ac.uk

Interdisciplinary projects

INT01 Making a plasma dry-etching system for micro-scale superconductor thin film patterning

Patterned superconducting thin filmsmay be used tomake exotic electromagnetic resonator structures for use in magnetic resonance and quantum technologies. Optical lithography using spun photoresist is capable of micron-scale resolution which is suitable for the devices in question. This project is to make a plasma etcher that iscapableofconvertingaNiobiumthinfilmcoveredindeveloped photoresist into a micropatterned structure. The project involves constructing, commissioning and testing a high mass-throughput vacuum system containing a cus-tom magnetron sputter platform fed by a radiofrequency matching network.Supervisor: Prof J Gregg Email: j.gregg@physics.ox.ac.uk

INT02 Supernova remnants in the Galaxy

Design, build and test a piece of electronic equipment of your The explosion of a supernova launches a blast wave into the low density interstellar medium. The shock accelerates relativistic electrons that emit synchrotron radiation. The ‘sigma-D’ relation between the radio brightness (sigma) and the diameter of the blast wave (D) shows that the radio luminosity decreases as the blast wave increases in diameter. The aim of the project is to explain this in terms of theoretical models of supernova remnants (SNR). At the last count (Green catalogue 2009) there are 274 known supernova remnants in the Galaxy, although not all have known distances (important for the sigma-D relation). An analysisofthestatisticswillbeusedtorefinethetheoreticalmodel. The statistical analysis will be performed using spread-sheet software such as Excel. The theory will by analytical. The student will need access to a desktop or laptop computer with Excel.Supervisor: Prof T Bell Email: t.bell1@physics.ox.ac.uk

INT03 Supernova remnants in the Large Magellanic Cloud

The explosion of a supernova launches a blast wave into the low density interstellar medium. The shock accelerates relativistic electrons that emit synchrotron radiation. The ‘sigma-D’ relation between the radio brightness (sigma) and the diameter of the blast wave (D) shows that the radio luminosity decreases as the blast wave increases in diameter. The aim of the project is to explain this in terms of theoreti-cal models of supernova remnants (SNR). The 45 known SNRinthenearbyLargeMagellanicCloudgalaxy(http://arxiv.org/abs/1006.3344)make a good set for statisticalanalysis because the distance is the same to all SNR in the LMC.Ananalysisofthestatisticswillbeusedtorefinethetheoretical model. The statistical analysis will be performed using spread-sheet software such as Excel. The theory will by analytical. The student will need access to a desktop or laptop computer with Excel.Supervisor: Prof T Bell Email: t.bell1@physics.ox.ac.uk

INT04 Nuclear Resonance observed using Cold Elec-tronics

Nuclear Magnetic Resonance (NMR) and Nuclear Quadru-pole Resonance (NQR) are powerful techniques for investi-gating the physics of unusual magnetic materials at very low temperatures. They work by treating the nuclei of the various atom types in the crystal as spies that can be questioned as regards what they see around them in their locality in the crystal. Both techniques involve questioning the nuclei us-ing radiofrequency electronics that is tuned to the nuclear resonance frequency. In NMR this resonant frequency is de-pendent on both the nuclear environment and on the strength ofanexternalmagneticfieldthatisappliedtothesample.In NQR the nuclear resonance is uniquely determined by the interaction of the nuclear quadrupole moment with its local electricfieldgradient.Typicalmagneticresonancespectrom-eters are limited in tuning range and signal-to-noise perfor-mance by the physical separation between the cold sample and the ambient temperature radiofrequency electronics. This project aims to use GaAs electronics working at liquid heliumtemperaturestomakeaNMR/NQRspectrometerofunparalleled sensitivity and tuning range. A familiarity with basic magnetism and Ohm’s Law and a lively awareness of Maxwell’s equations will prove very useful to whoever undertakes this challenge.Supervisor: Prof J Gregg Email: j.gregg@physics.ox.ac.uk

INT05 Nuclear magnetic resonance (NMR) investiga-tion of correlated metal oxides

Solid state Nuclear Magnetic Resonance (NMR) and Nuclear Quadrupole Resonance (NQR) are invaluable and important tools in experimental condensed matter physics. Through measurementofthenuclearhyperfinefield,awealthofusefulinformation about the properties of materials at the atomic level can be obtained. A historical triumph of this method was the application of 89Y, 63,65Cu and 17ONMR/NQR toestablish the d-wave nature of the superconducting cooper pairsinthehighTcCuprates–oneofthedefiningresultsin one of the most important stories in physics this century.

WeshallbecommissioninganewNMR/NQRspectrometerin 2015 capable of operating at temperatures as low as 10 mK. Using this instrument, we shall address fundamental questions that cannot be answered easily by other techniques including the unravelling of complex magnetic orders, and the probing of unusual low-temperature physics in so-called “spin ices”. This project will involve designing and perform-ing an experiment using the spectrometer, and analysing the results. This research forms part of a collaborative project involving several groups within the Condensed Matter Phys-ics sub-department with a relatively broad range of interests and expertise. It would suit a student who is keen to learn a little about a several different areas of experimental research, and who is interested in electronics, cryogenics, magnetics, or any combination of the three.Supervisors: Dr A Princep, Dr A Karenowska and Prof J Gregg Email: Andrew.Princep@physics.ox.ac.uk, j.gregg@physics.ox.ac.uk; A.Karenowska@physics.ox.ac.uk

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INT06 Laboratory investigation of volcanic lightning mechanisms

Volcanic lightning is one of the most spectacular displays nature can put on, and yet little is understood about the mechanisms generating lightning in an ash plume, and why some volcanoes generate so much more lightning than oth-ers. Triboelectric (frictional) charging is almost certainly involved, but it is unclear how much charge transfer occurs between different materials according to differences in workfunction (like the charging of a balloon on your jumper), and how much is contributed by a different mechanism caus-ing electron transfer between identical materials (the same mechanism that causes problems in industrial contexts such as grain and powder factories). This project will measure the charge transfer associated with specially prepared samples of materials often found in volcanic plumes, such as glass, and assess the relevance of the different charging mecha-nisms to the real ash plumes. There is also the possibility of testing samples of Martian or lunar analogue material to investigate charging in other planetary environments. This is an experimental project which would suit a student with interests in geo- or atmospheric physics.Supervisor: Dr K Aplin Email: k.aplin@physics.ox.ac.uk

INT07 Measuring Cerebrovascular Reactivity using Magnetic Resonance Imaging

MRI can be used to image both structure and function in the human brain, but it can also be used to determine the health of the cerebrovasculature, by measuring the response ofbloodflowinthebraintoinspiredcarbondioxide.Thisbloodfloweffect is called the cerebrovascular reactivity(CVR). It is usually measured in terms of a relative change inbloodflowcausedbydynamicchangesininspiredCO2.However, we hypothesise that it would be more robust to quantitativelymeasurebloodflowatrestandinasteadystateof increased inspired CO2. The project would compare the 2 methods. This project will take place at Oxford’s Centre for Functional MRI of the Brain (FMRIB) and the student will be a member of the FMRIB Physics Group, comprising about 20 engineers and physicists. This project requires good computational skills and some knowledge of programming (both MATLAB and image analysis software be used in the project). In addition to analysing and interpreting data, the student will be involved in acquiring MR images and will have the opportunity to interact with basic and clinical neuroscientists at FMRIB who are interested in using this new technology.

Location: FMRIB Centre, John Radcliffe Hospital, (see http://www.fmrib.ox.ac.uk)Supervisor: Dr D Bulte Email: daniel.bulte@ndcn.ox.ac.uk

INT08 Investigating the microstructure of iron deposi-tion in the human brain using MRI

Magnetic resonance imaging (MRI) is able to resolve the structure of soft tissues like the brain. However, the micro-scopic structural properties of brain tissue play an important role in the overall health of the brain. Iron levels have been implicated in a host of neurological disorders including Par-kinson’s disease, Alzheimer’s disease and multiple sclerosis. It has previously been shown that the reversible relaxation rateR2′(R-2-prime)iswellcorrelatedwithironload.ItisalsopossiblethattheR2′-weightedsignalcontainsinforma-tion about the structure of these iron deposits. In this project we will investigate the effect of the scale of iron particles ontheR2′-weightedsignalandwhetheritaffectsourabilityto measure the overall iron load accurately. This will also involvesimulationsoftheR2′-weightedsignal.Theprojectwill take place at Oxford’s Centre for Functional MRI of the Brain (FMRIB) and the student will be a member of the FMRIB Physics Group, comprising about 20 engineers and physicists. This project requires good computational skills and some knowledge of programming (MATLAB or C). In addition to analysing and interpreting data, the student will be involved in acquiring MR images and will have the op-portunity to interact with basic and clinical neuroscientists at FMRIB who are interested in using this new technology.

Location: FMRIB Centre, John Radcliffe Hospital, (see http://www.fmrib.ox.ac.uk)Supervisor: Dr N Blockley Email: nicholas.blockley@ndcn.ox.ac.uk

INT09 Modelling cancer cell growth in multicellular spheroids

To study cancer cell growth, tumour cells can be grown in small spherical aggregates (multicellular spheroids). Labora-tory data obtained from co-culturing two different cell lines, each with a different sensitivity to radiation, shows that the more resistant cells cluster in the centre of the spheroid, with the more sensitive cells towards the periphery. It is also known that the oxygen concentration decreases towards the centre of the spheriod as demand outstrips diffusion. In this project, mathematical simulations of cell division will be used to explore whether the observed clustering can be explained simply by preferential growth of one cell line over the other, or whether an active cell migration process is also necessary. A two dimensional cellular automata (or Monte Carlo) approach will initially be taken with the aim of extending to 3D, and potentially considering other mod-eling approaches depending on how the project develops. The laboratory data which the project will be based on has already been acquired. Although no previous experience is necessary an aptitude for computing and an interest in using Matlab(orotherhigh-levellanguage)wouldbebeneficial.

This project is entirely computer modeling. Dr Partridge’s research group is located on the Old Road Campus, so some tutorials will take place on this site. Biology input will be provided in collaboration with Dr Pavitra Kannan.Supervisor: Dr M Partridge Email: Mike.Partridge@physics.ox.ac.uk

INT10 Solid state radiation detector for environmental radioactivity monitoring

An inexpensive solid state radiation detector based on PiN diode technology has been designed and constructed for monitoring of natural radioactivity. The project will involve calibratingthedetector’sefficiencyandenergyresolutionwith respect to gamma radiation using laboratory radioactive sources. It will also involve devising a way to distinguish the signals from cosmic ray muons and natural background radiation from radon and thoron decay. This is very much a hands-onprojectandwouldbeagoodfitforastudentwhois interested in experimental particle and/or atmosphericphysics. Skills or interests in any or all of electronics, instru-ment development and the possible commercialisation of the device would also be useful.Supervisor: Dr K Aplin Email: k.aplin@physics.ox.ac.uk

INT11 & 12 An Electronics Project

Design, build and test a piece of electronic equipment of your choice. The project will take place on the Practical Course electronics laboratory.

Suggested Reading:

Horowitz and Hill

Any book on electronics.Supervisor: Dr R Nickerson Email: r.nickerson@physics.ox.ac.uk

INT13 Geophysics and industrial applications for SQUID magnetometry

SQUID magnetometers have enormous potential for geo-physicsapplicationsastheycanmonitormagneticfieldstoaresolutionover1000timesbetterthanconventionalfluxgatemagnetometers. This project will investigate the potential for these sensors to improve the performance of geophysical explorationtechniquesusingmagneticfields,withpotentialindustrial applications in monitoring groundwater and the search for mineral and energy resources. This project will involve modelling magnetic signals and comparing simu-lations to magnetometry data recorded in an underground laboratory, in order to determine the sensitivity for probing the underground electrical conductivity. This is an interdis-ciplinary project using data from an instrument developed for the cryoEDM particle physics experiment, in order to investigate geomagnetic phenomena. Supervisor: Dr S Henry Email: s.henry@physics.ox.ac.uk

INT14 &15 Very-high-energy gamma-ray astro-physics with the Cherenkov Telescope Array

Veryhigh-energygamma-rayastrophysicsisanexcitingfieldspanning fundamental physics and extreme astrophysical processes. It will soon be revolutionized by the construc-tion of the international Cherenkov Telescope Array (CTA; http://www.cta-observatory.org/).Thiswillbethefirstopenobservatory for very-high energy gamma-ray astronomy, and will be sensitive to photon energies up to 10^15 eV. Its science goals are:

(1) Understanding the origin of cosmic rays and their role in the Universe.

(2) Understanding the natures and variety of particle ac-celeration around black holes.

(3) Searching for the ultimate nature of matter and physics beyond the Standard Model.

CTA will consist of up to one hundred imaging air Cheren-kov telescopes using state-of-the-art Silicon Photomultiplier detectors and high-speed digital signal processing to detect and characterize the electromagnetic air shower caused when an astrophysical gamma-ray enters the Earth’s atmosphere.

I expect to be able to take up to two M.Phys. students this year working on either experimental or theoretical aspects of the CTA programme. These would suit students taking either the Astrophysics or Particle Physics options.

In the lab, we work on the design and construction of the cameras for CTA’s small-sized unit telescopes. These will have~2k pixel SiPMdetectors and front-end amplifierswhich feed into custom electronics using ASICs and FPGAs. This gives a system that can image at a rate of a billion frames per second.

On the theoretical/observational side of the programme,recently we have developed new theoretical models for the broad-spectrum emission from steady-state jets (Potter & Cotter 2012, 2013a,b,c) that let us use the gamma-ray observations and those at other wavelengths to investigate the physical properties of the jet and the black hole at its base. We now propose to extend these models to look in particularat(i)rapidvariabilityandflaringinjetsand(ii)entrainment of heavy particles as the jets propagate through their host galaxy, and the resulting possibility of hadronic particle processes within the jets. We will investigate how CTA may be used to determine the physical conditions that leadtoflaringandthepresence,andextent,ofemissionfromhadronic processes.

References

Actisetal.2010,http://arxiv.org/abs/1008.3703

Potter&Cotter2012,http://arxiv.org/abs/1203.3881

Potter&Cotter2013a,http://arxiv.org/abs/1212.2632

Potter&Cotter2013b,http://arxiv.org/abs/1303.1182

Potter&Cotter2013c,http://arxiv.org/abs/1310.0462Supervisor: Dr G Cotter Email: garret@astro.ox.ac.uk

INT16 Cold Electronic Instrumentation for Single Microwave Photon Experiments

More details from the supervisors.Supervisors: Prof J Gregg and Dr A Karenowska Email: j.gregg@physics.ox.ac.uk; A.Karenowska@physics.ox.ac.uk

INT17 An electronics project: precise experimental control using an FPGASuitable for someone with a strong interest in electronics. The project can be tailored to individual interest but we are aiming to produce a system to control various tasks in an experiment on ultracold atoms. Supervisor : Prof C Foot Email : Christopher.Foot@physics.ox.ac.uk

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Particle and Nuclear Physics projects

PP01 Study of the impact of cosmic-ray induced events in Liquid Argon detectors

Liquid Argon (LAr) detectors offer exquisite resolution im-ages of particle interactions and provide great background rejections. They are therefore optimal detectors for neutrino physics. It is believed that the resolution is good enough to reject any event induced by cosmic rays. However some particular cosmic-ray interaction could mimic signal events and contaminate signal samples. Both the MicroBooNE and LAr1-ND detectors will face the challenge of running on the surface. It is therefore crucial to understand in details what background can be introduced by cosmic rays. This project will require the use of the MicroBooNE and LAr1-ND analy-sis software (ROOT-based, i.e. C++) to study the cosmic-ray background as well as any ways to mitigate it. This study is extremely relevant to all future neutrino LAr detectors.

Computing requirements: Knowledge of C++ language (knowledge of ROOT is an advantage)Supervisor: Dr R Guenette Email: Roxanne.Guenette@physics.ox.ac.uk

PP02 The MicroBooNE detector

The MicroBooNE detector, a 170t Liquid Argon Time Pro-jection Chamber at Fermilab, is starting it’s commissioning. During the next months, data coming from cosmic rays and from the off-axis NuMI beam will be of great use to understand the performance of this state-of-the-art technol-ogy. During this project, the student will use the calibration data in order to test some properties of the detector such as electron life-time, electron recombination factors and event reconstructionefficiency.Thestudentwillusetheanalysissoftware (ROOT-based, i.e. C++) to perform the different analyses. This project will be of great interest for the future of the MicroBooNE experiment and will allow the student to develop several aspects of data analysis of LAr experiments.

Computing requirements: Knowledge of C++ language (knowledge of ROOT is an advantage)Supervisor: Dr R Guenette Email: Roxanne.Guenette@physics.ox.ac.uk

PP03 ATLAS Physics

The world’s highest energy particle accelerator, the Large Hadron Collider (LHC) at CERN, started operation at the high-energy frontier in 2009. Constructed in a 27 km long circular tunnel, 100 meters underground, it accelerates two counter-rotating proton beams and brings them into collision at center-of-mass energies of up to 14 TeV. By pushing the energy frontier by an order of magnitude above that previ-ously accessible, it offers unprecedented opportunities to explore the fundamental constituents of the universe.

The ATLAS and CMS experiments have observed a new boson, and this opens up a new research area with the aim of understanding if this particle is a Higgs boson and, if so, whether it a Standard Model (SM) Higgs boson or a more exotic version. Studies can be carried out with the existing data to begin to address these issues, such as determining the spin of the boson. Even if the new particle turns out to be compatible with a SM Higgs, there are many remaining problems in the SM, many of which point to the existence of

exotic physics in the LHC energy range. Hence a primary goal of ATLAS is to explore SM physics in new energy regimes and to discover new physics signatures beyond the SM. Possibilities include Supersymmetry (SUSY) as well as models which posit the existence of additional spatial dimensions beyond our normal experience.

In addition, the LHC is a “factory” for W and Z bosons and top quarks, enabling not only systematic studies of their properties but also their use as precision tools to probe the deep structure of the proton and to guide searches for physics beyond the Standard Model.

PP0301 Beyond the Standard Model with Highly Energetic Jets

Jets of particles arising from highly energetic quarks, gluons, and electroweak gauge bosons are characteristic of a number of signatures expected from physics from beyond the Stand-ard Model, such as extra spatial dimensions, symmetries, and vector-like quarks. A current priority is to improve our understanding of the internal structure of these jets in order to move beyond the standard jet reconstruction and tagging techniques which have been employed at lower energies.

Recent outcomes have been documented in Phys. Rev. D88 (2013) 014044 and at the 5th nternational Workshop on Boosted Object Phenomenology, Reconstruction and Searches (BOOST 2013). The proposed project will take this and related work further. These studies will primarily be based on simulations of high-energy collisions, but may incorporate data from the ATLAS detector.

Much of the work for this project will involve computing, inparticularusingC++andROOTanalysissoftware(http://root.cern.ch) on Linux.Supervisor: Dr J Tseng Email: j.tseng1@physics.ox.ac.uk

PP0302 Direct Measurement of the invisible width of the Z using ATLAS data

This project aims to do a direct measurement of the invisible width of the Z by using ATLAS data to measure the ratio (Z+jet, Zνν)/(Z+jet,Z e+e-) and then using the well measuredvaluefromLEPforΓ(Z e+e-) to determine the invisiblewidthoftheZ,Γinv. The analysis uses the full 2012 ATLAS data and this allows for a very precise measurement, which is sensitive to any new physics which produces par-ticles that decay into weakly interacting particles. The data sets and Monte Carlo simulations are available, so the project will give students an opportunity to do a real data analysis.

Skills required: some experience with writing computer soft-ware would be required. The student(s) should be taking the C4 major option in order to have the necessary background to do this project.Supervisor: Dr T Weidberg Email: t.weidberg1@physics.ox.ac.uk

INT18 Investigation of a low distortion oscillator

More details from the supervisor.Supervisor: Dr G Peskett Email: g.peskett@physics.ox.ac.uk

INT19 tbc

More details from the supervisor.Supervisor: Prof G Yassin Email :g.yassin@physics.ox.ac.uk

INT20 Adaptive percolation

Percolation models can described a broad class of problems in which a network partially breaks down, and one is in-terested in knowing whether the remaining network is still largely interconnected. Such models are applicable in many contexts such as gelation, electrical networks, contagious dis-ease propagation, and opinion propagation. A feature that is usually not considered in percolation is the ability for a node to rewire itself when some breakdown occurs in the network. In this project, the student will focus on a class of problems in which nodes have an internal variable that moves rapidly to zero as the overall connectivity of the system diminishes, and the remaining nodes try to rewire the network to stop the collapse. The lower the sum of the internal variables over the remaining network, the worse the state of the network, simulating a situation akin to a cascading failure, which can occur in networks of information sharing, ecological networks, and economic networks. Understanding percola-tion in this context can provide valuable insights about the dynamics that take place in complex adaptive systems. The student will develop analytical models and computational simulations in order to develop a comprehensive theory. Depending on time and student interests, the theory can be tested with empirical data of a variety of topics and laboratory experiments. Students of all tracks can work on this project, and one or two students can participate.

Skills: Computer programming. High level languages such as python or medium level languages such as C or Fortran. Supervisor: Dr E Lopez Email: eduardo.lopez@sbs.ox.ac.uk

INT21 Statistical Mechanics of human interaction in cities.

It has recently been observed that quantities that describe human behaviour in cities (wages earned, number of patents filed,numberofcrimesreportedetc.)scalesuper-linearly(power law with exponent greater than one) with city size. Viewed as a statistical mechanical system, human interaction among people is key to the manifestation of super-linearity; otherwise quantities remain linear with respect to city size. By using empirical data collected from social network sys-tems such as twitter, which often also has spatial location information, one can infer levels of human interaction in cities. This project entails building statistical mechanical models that consider human interaction as a form of interac-tion between particles, with the ultimate goal of explaining the power law behaviour observed in data. The student will focus on building both computational and analytical mod-els of the problem and, depending on preference, can also

perform some data collection along with the other activities of the project. This work is suited for students on any of the tracks, and can accommodate multiple students.

Skills: Computer programming. High level languages such as python or medium level languages such as C or Fortran.Supervisors: Dr E Lopez Email: eduardo.lopez@sbs.ox.ac.uk

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PP0303 Precise measurement of the W boson mass

Prior to the discovery of the Higgs boson, its mass was pre-dicted by precision measurements of electroweak parameters, including the W boson mass. The knowledge of this mass provides a key constraint in determining what might lie be-yond the Higgs boson. Future measurements of the W boson masswithATLASandCDFdatawillsignificantlyreducethecurrent uncertainty on this quantity and further constrain the properties of new particles (or suggest their existence). This project will focus on reducing the important uncertainties in the measurements.Supervisor: Dr C Hays Email: hays@physics.ox.ac.uk

PP0304 Measurement of Higgs boson production in decays to W bosons

The 2012 observation of a new resonance with properties consistentwiththatofaHiggsbosonprovidesthefirststepin understanding the source of particle mass. Further meas-urements of the Higgs boson couplings to SM particles will determine if the Higgs is the sole source of this mass. An important coupling is that of the Higgs boson to W-boson pairs, which is tightly constrained by measurements of the W boson mass. Precisely measuring the Higgs-to-WW cou-pling will provide a standard against which other coupling measurements can be compared. This project will focus on the many theoretical uncertainties in this measurement.Supervisor: Dr C Hays Email: hays@physics.ox.ac.uk

PP04 Search for neutrinoless double beta decay at SNO+

SNO+ is an experiment designed to look for neutrinoless double beta decay, which would indicate that neutrinos are their own anti-particles, could help explain why neutrino masses are so small, and shed light on possible dark matter candidates and other non-Standard Model physics. The experiment will use about a tonne of Tellurium dispersed in 1000 tonnes of liquid scintillator in order to pick up faint tracesoflightwhichresultfromthisdecay.Possiblespecificprojectsincludetherefinementofalgorithmstorecognizethese faint traces, and to investigate the effect of low energy radioactive backgrounds on the experiment’s sensitivity. Some familiarity with C++ and Linux would be an advantage.Supervisors: Prof S Biller, Dr A Reichold and Dr J TsengEmail: s.biller@physics.ox.ac.uk, a.reichold@physics.ox.ac.uk, j.tseng1@physics.ox.ac.uk

PP05 The Higgs as probe for new physics

In 2012 the Higgs boson was discovered in collisions of the Large Hadron Collider at CERN. Run 2 of the LHC will start this year and will allow more detailed studies of the properties of this particle. The measurement of the “off shell” production of HZZ2l2νathighinvariantmassis sensitive to the Higgs boson total decay width and to new physics. In particular, it is generally sensitive to new particles that affect the Higgs boson mass and thus offer a solution to the so-called “hierarchy problem”. The candidate for this project will use MADGRAPH, a Monte Carlo which includes SM and the MSSM effects in the determination of the Higgs gluon fusion cross section, to investigate the sensitivity of the 2l2νtransversemassdistributiontonewphysics.Supervisor: Prof D Bortoletto Email: Daniela.Bortoletto@physics.ox.ac.uk

PP06 Photon recognition algorithms for dark matter searches

Dark Matter Searches based on detection of WIMP scat-tering in noble liquids, such as xenon for example, rely on efficientalgorithmsforextractingsinglephotonsfromPMTdata. This project aims to develop such algorithms and test them against real data and simulation. The project requires proficiencyinC++andROOT,bothofwhichcanbelearntastheprojectprogressesandthespecificknowledgeonROOTis not very demanding.Supervisor: Prof D Bortoletto Email: Daniela.Bortoletto@physics.ox.ac.uk

PP07 Simulation of background sources on dark matter experiments

This project will build a model (in GEANT) of a simple dark matter detector and explore the effects various types of radioactiveimpuritiesinmaterialshaveonthefinalresult.Experience in GEANT would be useful, but can be acquired quicklywithsufficientbackgroundinC++programming.Supervisor: Prof H Kraus Email: h.kraus@physics.ox.ac.uk

PP08 Dark Matter Direct Detection experiment Background simulation

The LUX-ZEPLIN direct dark matter search experiment will use a large quantity of liquid xenon to search for dark matter in the universe. The xenon in its container is instrumented by a large number of photomultipliers and plenty of other sensors and instrumentation, each of which must be as radio-pure as possible. How pure is pure enough is the main topic of this project. The GEANT4 software framework will be used to carry out the simulations, assessing the impact of various impurities on the performance of the experiment, and viable solutions for the components (choice of material, geometry, etc) in question might be developed from this. Some C++ experience, or the ability to learn this quickly, is an essential requirement. The software package GEANT4 will be used. Prior experience with GEANT4 would be good.Supervisor: Prof H Kraus Email: h.kraus@physics.ox.ac.uk

PP09 Search for rare annihilation decays of B-mesons using the 3fb-1 LHCb Run I dataset

ThedecayB+→Ds+φoccursintheStandardModel(SM)via annihilation of the quarks forming the B+ meson into a virtual W+ boson.

Annihilation diagrams of B+ mesons are highly suppressed in the SM; no hadronic annihilation-type decays of the B+ meson have been observed to-date.

Branching fraction predictions (neglecting rescattering) for B+→Ds+φare(1−7)×10−7intheSM.

An 2012 publication from the 1fb-1 LHCb data revealed evidenceofasignalat3sigmasignificancewithabranchingfraction,(19+/-8)×10−7.

The project goal will be to repeat this analysis with the full dataset.

The increase in cross section and improved selection leads to an expectation of a quadrupling in signal size which should turn this evidence into an observation.

Additionally the analysis will extend to a measurement of B+ →D+K*whichproceedsbytheidenticalannihilationpro-cess, except a ddbar pair is ‘popped’ instead of an ssbar pair.

The project will involve some collaboration with colleagues the Yandex Institute(Russia) and well as the close assistance of the Oxford LHCb group.

The main themes of the project will be to write a signal ex-tractionlikelihoodfitanddealwiththestatisticalinferences.

Some experience programming in a Linux environment is importance, Prior use of python and C++ is advantageous for a quick start.Supervisor: Dr M John Email: Malcolm.John@physics.ox.ac.uk

PP10 Reactor anti-neutrino measurements with the Solid experiment

TheSolid experimentwill probe the observed deficit ofneutrinos close to nuclear reactors. In the Spring of 2015 thecollaborationdeployedthefirstmoduleofanovelanti-neutrinodetectortomeasuretheanti-neutrinoflux5mfromthe core of the BR2 reactor at SCK-CEN in Mol, Belgium. The small collaboration, run from Oxford, are looking for anMPhysstudenttoanalysethefirstdatacollectedbythenewmoduleandassistinperformingtheanti-neutrinofluxmeasurement. This will be the shortest distance from a reac-torcorethataprecisefluxmeasurementhasbeenperformedand will have a large impact on the understanding of the reactor neutrino anomaly. The project will involve writing data analysis programs, and so experience in programming inC/C++and/orPythonwouldbehelpful.Supervisors: Mr N Ryder and Prof A Weber Email: nick.ryder@physics.ox.ac.uk

PP11 Analysis of two-phase flow properties in thin evaporators

The state-of-the-art method of cooling silicon detector track-ing systems in particle physics experiments is evaporative cooling. Due to the push to minimize material in the system the geometries of the evaporators are optimized for small sizeandmassflows.Tounderstandtheperformanceoftheevaporative cooling within these constraints the pressure drops and heat transfer properties in the thin tubes need to be accurately understood.

This project will take data taken with realistic evaporator geometries using evaporative CO2 cooling and analyse the pressuredropsandheat transfercoefficient,andcomparetheresultstodifferentmodelsof2-phaseflowandboiling.The project will require programming skills (C++ and use of the data analysis package ROOT).Supervisors: Dr G Viehhauser and Dr A Reichold Email: G.Viehhauser1@physics.ox.ac.uk, a.reichold@physics.ox.ac.uk

PP12 Study of detector alignment for future particle physics tracking detectors

A critical requirement for the performance of tracking de-tector systems used for particle physics experiments is the knowledge of the position of the several 10,000 sensors in the system to the level of µm. The most powerful technique toachievethisgoalistofitthesensorpositionsusingthedatafrom the tracker itself. It is employed in the largest tracking systems to-date, in the ATLAS and CMS experiments. Future tracking systems, now under discussion for the Linear Col-lider or the FCC, will be even larger and have even higher demands on the point measurement accuracy.

Asoftwarepackagetoperformthemulti-parameterfit,Mil-lipede II [ ], has been developed within the framework of the CMS experiment. This project would use this package and adapt it to geometry models for the future linear collider and use it to study optimization of the layout and mechanical aspects of this tracking system.Supervisors: Dr G Viehhauser and Dr A Reichold Email: G.Viehhauser1@physics.ox.ac.uk, a.reichold@physics.ox.ac.uk

PP13 Precision particle physics: g−2

Themuong−2experimentwillsearchfornewphysicsbe-yond the standard model of particle physics by making a pre-cision (0.14ppm) measurement of the anomalous magnetic dipole of the muon – how much the muon g factor deviates from two. This involves measuring two quantities: the muon precessionfrequency;andthemagneticfieldmagnitude.

This project will involve simulations of the signals from an NMR magnetometer under development at Oxford to provide an absolutemagneticfield reference for this experiment,with the aim of developing the best technique to extract the frequency of a noisy signal to ppb precision. The student will begin by investigating different analysis techniques, and then test these with sample data.Supervisor: Dr S Henry Email: s.henry@physics.ox.ac.uk

PP14 Radiaoactivity screeing for the LUX-ZEPLIN experiment

LUX-ZEPLIN is a next generation dark matter detector that will build on the recent success and sensitivity of the LUX-350 detector. In order to achieve the required levels of sensitivity, it is important that the radioactive contamination of all components is both known and minimised. A suite of high-purity germanium detectors are currently being installed at the Boulby Underground Laboratory that will allow the measurementofcontaminationstobelowthelevelof1mBq/kg. The project will concentrate on the simulation of the de-tector setup using GEANT4 and software from CANBERRA and on the analysis of data acquired from a wide variety of samples. The results of the project will be used to determine whichcomponentspasstherigorousspecificationsfortheLZ experiment and will help to predict the overall level of background in the detector. The student will need to be confidentinprogramminginc++althoughallsoftwareandsupport will be provided.Supervisor: Dr P Scovell Email: Paul.Scovell@physics.ox.ac.uk

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PP15 B0 Meson Tagging

The B0 meson is bound state of the bottom quark and the down quark. These mesons are produced at the Fermilab Tevatron in generous amounts. Our understanding of quantum mechanics indicates that the neutral B meson will spontaneously change into its anti-particle and then change back as it travels through space before it decays. This effect is called ‘mixing’ and has already been observed in the neutral kaon system and in the neutral B0 mesons. It has only recently been observed in the BS meson.

BS mixing occurs quite rapidly. Current experimental meas-urements on BS mixing indicate that the BS changes into the anti-BS on average 17 times before decaying. This is astonishing when one realizes that the BS lifetime is just a little over one picosecond. B0 meson mixing, however, takes place at a more stately pace, requiring approximately 5 lifetimes of the meson for one complete mixing oscillation.

Before one can measure mixing however we need to know whether the meson started out life as a particle or an antiparti-cle. The meson needs to be ‘tagged’ as either one or the other.

The goal of this project is to explore various tagging tech-niques on neutral B mesons using the CDF data taken at 2.0 TeV centre of mass energy. The student will attempt to meas-uretheefficiencyanddilutionoftaggingmethodsinthesetwo cases in CDF data and compare these to the measured rates for charged hadrons and also MC simulations.

Specialized equipment needed: Computer Access

Knowledge of Computer programming required: Yes, C++ programming is best.

Suggested Reading:

See Dr. Huffman’s web site under the MPHYS project section for a reference about B mesons at CDF.

http://www-pnp.physics.ox.ac.uk/~huffman/

IntroductiontoElementaryParticles,byDavidGriffiths,sec-tion 4.8 gives a very good explanation of mixing in the kaon system. Apart from the fact that the BS meson has a much shorter lifetime, the arguments are identical. The original Kaon paper is referred to here and that too is recommended.

Collider Physics, by Barger and Phillips. In particular the sections on B meson physics and B meson mixing.

F. Abe et. al. (The CDF Collaboration), Phys. Rev. D60, 072003;Thefirstpageanditsreferencesgiveanoverviewof mixing but this is a very advanced paper.Supervisor: Dr T Huffman E-mail: t.huffman@physics.ox.ac.uk

PP16 Measuring the Caesium Flux Escaping an Ion Source Plasma

Design and test a surface ionisation probe (SIP) to measure thefluxofcaesiumatomsescapingtheplasmaof theionsource used on the ISIS proton accelerator. The SIP will con-sist of two small loops of wire in vacuum which will measure the current of ionised caesium on a precision picoammeter.

A suitable candidate for this project will learn how to design low-noise in-vacuum electrical circuitry and have hands-on experience of constructing intricate wiring inside a particle

accelerator. The design and testing of the SIP can be per-formed at Oxford, so only occasional travel to RAL will be required. This is a rare and stimulating opportunity to see behind the scenes of a real particle accelerator.Supervisors: Mr S Lawrie and Dr I Konoplev Email: Scott.Lawrie@physics.ox.ac.uk, Ivan.Konoplev@physics.ox.ac.uk

PP17 Plasma Spectroscopy Measurements Using a High Resolution Optical Monochromator

Measure the fundamental plasma properties of the ion source used on the ISIS proton accelerator using a high resolution optical spectrometer. The hydrogen-caesium plasma glows a beautiful bright pink, whose precise colour components inform the optimal operation of the ion source. Measure-ments of emission line amplitudes and widths will be used to calculate important plasma properties such as particle densities and energies. These parameters will then be used torefinethedesignofanewionbeamextractionelectrode.A suitable candidate for this project will have a passion for particle accelerators, be competent in performing rigorous, methodical optical measurements and be able to travel to RAL. This is a rare and stimulating opportunity to see behind the scenes of a real particle accelerator.Supervisors: Mr S Lawrie and Dr I Konoplev Email: Scott.Lawrie@physics.ox.ac.uk, Ivan.Konoplev@physics.ox.ac.uk

PP18 Algorithms for longitudinal profile image re-construction of femtosecond electron bunches

Imagingoflongitudinalfemtosecondelectronbunchprofileis a key to successful implementation of next generation of state-of-the-art accelerators and their application for gen-eration of coherent THz and X-ray radiation. A number of imaging technique based on spectral analysis of coherent radiation generated by the electron bunches are available. However the problem of uniqueness of the reconstruction and its stability is still not resolved, especially for a bunch of complex shape. The project proposed will be based on development of numerical algorithms based on Kramers-Kroening and Bubble-Wrap techniques. It will involve the research based on both analytical and numerical studies as well as analysis of the spectral data observed at FACET, SLAC (Stanford University, USA) and Diamond light Source, (Harwell Science Park, UK). It is expected that at the end of the project a sophisticated spectral analysis tools based on novel algorithm will be developed. The knowledge of programming techniques and mathematical methods is essential for this project. Supervisors: Dr R Bartolini, Dr I Konoplev and Dr G Doucas Email: r.bartolini1@physics.ox.ac.uk

PP19 Improving sensitivity to Supersymmetry at the 13 TeV Large Hadron Collider

Searches for supersymmetry at the 8 TeV run of the LHC have been shown to have sensitivity to various highly-constrained supersymmetry models. However much of the more general space for SUSY models is yet to be explored. This project uses both ATLAS experimental data and simu-lations of a more general set of SUSY models. You will use those data to identify and develop new types of analyses which, if performed on the 13 TeV LHC data, could lead to a discovery of SUSY.Supervisor: Prof A Barr Email: A.Barr1@physics.ox.ac.uk

PP20 Meeting the LHC data challenge

Over the next decade, the ATLAS experiment at the Large Hadron Collider will undergo a series of upgrades to allow it to search for physics beyond the Standard Model. One of the biggest challenges will be to rapidly select the collisions of interest, such as those with momentum imbalance - which would be the signature for new invisible particles such as Dark Matter candidates. This project involves working with state-of-the-art selection and processing computing hardware which has been designed to meet those challenges.Supervisor: Prof A Barr Email: A.Barr1@physics.ox.ac.uk

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Theoretical Physics projects

TP01 Precision determination of fundamental elec-troweak parameters at the Large Hadron Collider

At the Large Hadron Collider, the accurate measurements of electroweak parameters like the mass of the W bosons provides an robust stress-test of the Standard Model (SM) and an excellent window to possible New Physics beyond the SM. This requires to carefully control all sources of theoretical uncertainties, that in many cases are dominated by our limited knowledge of the internal structure of the proton, as characterized by the Parton Distribution Functions. The aim of these project is to study at a quantitative level the impact of the uncertainties on the value of the effective lepton mixing angle measured at hadron colliders due to the proton parton distribution functions. The value of the effective lepton mixing angle can be extracted, by means of a templatefit technique, fromdifferential distributionmeasured in the neutral current Drell-Yan process. In this project we will use state-of-the-art tools for the simulation of Drell-Yan production at the LHC, with emphasis on the role that the most updated determinations of the PDFs from various groups play. The goal is to estimate the how large QCD uncertainties are in the measurements of this important electroweak parameter at the LHC, and compare with the expected experimental precision.

Requirements

A solid background in computational techniques, in particular inC++programming,wouldbebeneficial,thoughcertainlynot essential. From the syllabus point of view, students that have followed the Subatomic physics options, advanced QM etc. would be better prepared.Supervisor: Dr J Rojo Email: Juan.Rojo@physics.ox.ac.uk

TP02 Searches for New Physics beyond the Standard Model at the LHC using ratios of cross-sections

The staged increase of the Large Hadron Collider beam energy (7 TeV, 8 TeV, 13 TeV and 14 TeV) provides a new class of interesting observables, namely ratios and double ratios of cross sections of various hard processes. The large degree of correlation of theoretical systematics in the cross section calculations at different energies leads to highly precise predictions for such ratios. The aim of this project is to provide state-or-the-art theory predictions of such ratios, and to study their possible implications, both in terms of opportunities for precision measurements and in terms of sensitivity to Beyond the Standard Model dynamics. This project will also involve to extend these calculations to 100 TeV, the center of mass energy of the proposed Future Circular Collider.”

Requirements

Aa solid background in computational techniques, in par-ticular inC++programming,wouldbebeneficial, thoughcertainly not essential. From the syllabus point of view, students that have followed the Subatomic physics options, advanced QM etc would be better prepared.Supervisor: Dr J Rojo Email: Juan.Rojo@physics.ox.ac.uk

TP03 Multilayer Networks

The student will undertake a project in “multilayer net-works.” In most natural and engineered systems, a set of entities interact with each other in complicated patterns that can encompass multiple types of relationships, change in time, and include other types of complications. Such systems include multiple subsystems and layers of connectivity, and it is important to take such “multilayer” features into account to try to improve our understanding of complex systems.

C o n s e q u e n t l y, i t i s n e c e s s a r y t o g e n e r a l i z e “traditional’”network theory by developing (and validat-ing) a framework and associated tools to study multilayer systems in a comprehensive fashion. In this project, the student will study a project in multilayer networks.

Reference: Kivelä, Mikko; Arenas, Alex; Barthelemy, Marc; Gleeson, James P.; Moreno, Yamir; and Porter, Mason A. [2014]. Multilayer Networks, Journal of Complex Net-works, Vol. 2, No. 3: 203-271.Supervisor: Dr M PorterEmail: porterm@maths.ox.ac.uk

TP04 Chemical evolution of the Milky Way and Satel-lite Galaxies

As kinematics, i.e. the motion of stars, change over their lifetime, the only information we have about the origin of a star, is its chemical composition together with some infor-mation on its age. This chemical composition is inherited from the gas cloud that collapses into the star, with very minor alterations afterwards. Understanding this information is key to quantify the history and dynamics of any stellar system, e.g. the components of our Galaxy or the evolution of dwarf galaxies.

The project will make use of an existing model of detailed chemical evolution of several elements, which is also ca-pable of predicting kinematic information and modelling observations we compare to. Depending on the progress of the project and the interests of the student, we will then try to explore the enrichment of dwarf galaxies and the Galactic halo or explore enrichment processes and gas streaming in the Milky Way disc.

The project demands good analytical and some program-ming skills (preferably in C++, though this can be acquired during the project).Supervisor: Dr R Schoenrich Email: Ralph.Schoenrich@physics.ox.ac.uk

TP05 Unveiling formation histories of massive ellipti-cal galaxies from distribution functions

Simulations of galaxy evolution suggest that massive ellip-tical galaxies have grown through a combination of in-situ star formation and accretion of neighbouring stellar systems. These processes should have left an imprint on the distribu-tion of positions and velocities of stars particularly in the outskirts of these galaxies where orbital timescales are long. Such distribution functions can quite easily be expressed in terms of ‘action integrals’. The goal of this project will be todevelopdistributionfunctions,fitthemtoobservedposi-

tions and kinematics of the stellar populations in a typical massive elliptical galaxy, and use the results to constrain the structure, gravitational potential, and more importantly history of these objects.

Programming skills are essential for this project, familiarity withC++andHamiltonianmechanicswouldbebeneficial.Supervisor: Dr R Schoenrich Email: Ralph.Schoenrich@physics.ox.ac.uk

TP06 Probabilistic parameter determinations of stars or galaxies

Until now, spectral analysis is more of an artwork than a quantitative science. Typically a spetroscopist will try to fitthespectrallinesofastarbyhand,inordertoobtainitsphysical parameters like temperature, metallicity, surface gravity, etc. However, with the advent of larger spectroscopic surveys, we need to quantify the errors on stellar parameters (which are key to quantitative comparisons with Galaxy models) in a more objective way and need strategies for the automatic assessment of stellar parameters. Similarly we need the full probability distribution functions in parameter space to combine the spectroscopic information with other sources, like photometry or astroseismology. We have cre-ated a fully integrated C++-based pipeline that performs this analysis and have successfully applied it to data from several surveys.

The student can choose to work on different aspects of this pipeline, from implementing astroseismic information and improvements on the Bayesian framework to studying details of algorithms underlying the spectroscopic analysis.

The project demands good analytical and good programming skills in C++, though this may be acquired during the project. Thestudentmightneedtodealwithastronomical.fitsfilesand potentially some IDL codes.Supervisor: Dr R Schoenrich Email: Ralph.Schoenrich@physics.ox.ac.uk

TP07 also AS02 Stress-Tensor Induced Instabilities in Accretion Disks

In the classical theory of accretion discs, the form of the turbulent stress tensor is based on dimensional reasoning and taken to be directly proportional to the gas pressure. But if, as is now widely believed, the underlying causes of the turbulence are magnetohydrodynamic (MHD), the behaviour of the stress cannot possibly be so simple. For example, if the disk had no free electrons, MHD could not operate, so this alone would introduces a more complex dependence on density and temperature. In reality, physics of magnetised plasmas issufficientlyrich thateven inanamply ionisedgas the stress tensor depends on temperature and density in a manner much beyond a simple pressure scaling. This more complex behaviour can easily lead to dynamical instability for the disc, which is precisely what observations seem to demand for many compact X-ray sources. In this project, wewillidentifyspecificprocessesrelevanttodilute(weaklycollisional) as well as strongly collisional astrophysical plas-mas that affect the behaviour of the turbulent stress, propose simple (but not too simple!) models of the latter, investigate their stability properties, and try to relate them to observed state changes seen in X-ray sources.

Background Reading:

J. Frank, A. King and D. Raine, Accretion Power in Astro-physics (Cambridge U. Press, 2002)

J.-P. Lasota, “The disc instability model of dwarf novae and low-mass X-ray binary transients,” New Astron. Rev. 45, 449 (2001)

S. A. Balbus and P. Henri, “On the magnetic Prandtl number behavior of accretion disks,” Astrophys. J. 674, 408 (2008)

S. A. Balbus and P. Lesaffre, “The effects of Prandtl number onblackholeaccretionflows,”NewAstron.Rev.51,814(2008)

A. A. Schekochihin, S. C. Cowley, F. Rincon and M. S. Rosin, “Magnetofluid dynamics ofmagnetized cosmic plasma:firehoseandgyrothermalinstabilities,”Mon.Not.R.Astron.Soc. 405, 291 (2010)

M. W. Kunz, A. A. Schekochihin, S. C. Cowley, J. J. Binney and J. S. Sanders, “A thermally stable heating mechanism for the intraclustermedium: turbulence,magnetic fieldsand plasma instabilities,” Mon. Not. R. Astron. Soc. 410, 2446 (2011)

M. W. Kunz, A. A. Schekochihin, S. C. Cowley, J. J. Binney and J. S. Sanders, “A thermally stable heating mechanism for the intraclustermedium: turbulence,magnetic fieldsand plasma instabilities,” Mon. Not. R. Astron. Soc. 410, 2446 (2011)Supervisors: Dr A Schekochihin (Theoretical Physics) and Prof S Balbus (Astrophysics)Email: a.schekochihin1@physics.ox.ac.uk, Steven.Balbus@astro.ox.ac.uk

TP08 also AS07 Topics in plasma physics and plasma astrophysics: turbulence, transport, magnetic fields

This project will adapt to the interests of the student who takes it up: those interested are urged to contact A. Schek-ochihin for a preliminary discussion of options.

Possible topics revolve around the fundamental question of energyflowsinanon-equilibrium,driven,multi-componentsystem that is cosmic (or laboratory) plasma: energy is typi-cally injected into it via some large-scale mechanism and then distributes itself between ions and electrons, magnetic and electricfieldsand–mostimportantly–degreesoffreedomin the 6-dimensional kinetic phase space (positions and velocities). The eventual fate of this energy, as always in physics, is to be thermalized, but in order for that to happen, ithastofinditswayfromlargescaleswhereit’sinjectedto small scales where it can be converted into heat via vari-ous plasma dissipation mechanisms [1,2]. In the process, a chaotic, self-organised, multiscale state emerges – plasma turbulence – which is both a fascinating object of study in itself [2] and also a background against which the large-scale dynamics are occurring – this background sets the effective transportproperties for the large-scalemotionsandfields(“turbulent” viscosity, “turbulent” thermal conductivity etc.)

This last aspect of turbulence theory is the route by which it findsitsapplicationstosuchquestionsasconfinementofheatin fusion devices (=what is the effective thermal conductivity of the turbulent plasma in a tokamak?) [3,4] or the transport of momentum in accretion discs towards the central black hole (=what is the effective viscosity of the turbulent plasma

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in a Keplerian disc?). Two other key “headline” questions associatedwithenergyflowsinplasmaturbulenceare:howis turbulent energy, when it thermalises, partitioned between different plasma species (ions, electrons)? and how is it partitioned between motions of the plasma and the magnetic fields?Thelatteristhefamousproblemofmagnetogenesis:canplasmaturbulencegeneratethemagneticfieldsthatareubiquitously observed in the Universe – in stars, interstel-lar and intergalactic medium – and how does it do it? [5,6]

References

[1] A. A. Schekochihin et al., “Gyrokinetic turbulence: a nonlinear route to dissipation through phase space,” Plasma Phys. Control. Fusion 50, 124024 (2008)

[2] A. A. Schekochihin et al., “Astrophysical gyrokinetics: kineticandfluidturbulentcascadesinmagnetizedweaklycollisional plasmas,” Astrophys. J. Suppl. 182, 310 (2009) [e-print arXiv:0704.0044]

[3] M. Barnes, F. I. Parra, and A. A. Schekochihin, “Criti-cally balanced ion temperature gradient turbulence in fu-sion plasmas,” Phys. Rev. Lett. 107, 115003 (2011) [e-print arXiv:1104.4514]

[4] E. G. Highcock et al. “Zero-turbulence manifold in a toroidal plasma,” Phys. Rev. Lett. 109, 265001 (2012) [e-print arXiv:1203.6455]

[5] F. Mogavero and A. A. Schekochihin, “Models of magnetic-fieldevolutionandeffectiveviscosityinweaklycollisional extragalactic plasmas,” Mon. Not. R. Astron. Soc., in press (2014) [e-print arXiv:1312.3672]

[6] M. W. Kunz, A. A. Schekochihin, and J. M. Stone, “Firehose and mirror instabilities in a collisionless shear-ing plasma,” Phys. Rev. Lett., submitted (2014) [e-print arXiv:1402.0010]Supervisor: Dr A Schekochihin Email: a.schekochihin1@physics.ox.ac.uk

TP09 Anyons and Topological Quantum Computing

One typically learns in quantum mechanics books that identi-cal particles must be either bosons or fermions. While this statement is true in our three dimensional world, if we lived in two dimensions, more general types of particles known as “anyons” could exist. While this sounds like just a math-ematicalflightoffancy,infact,whenwerestrictparticlesto move only within two dimensions, such exotic particles can (and sometimes do) emerge as low energy excitations of condensed matter systems, and various experiments have claimed to observe this behavior. It has been proposed that such anyons could be uniquely suited for building a so-called “quantum computer” — a computer that could in principle use the unique properties of quantum mechanics to perform certain types of calculations exponen- tially faster than any computer built to date.

Thefirstobjectiveofthisprojectistolearnabouttheprop-erties of anyons, where these particles exist, and how these particles might be used to build a computing device. A few toy model calculations will start the student in the direction of modern research.

The project is suitable for a mathematically strong student taking the Theoretical Physics option. This work will involve analytical calculations, abstract mathematics, and probably

some computing based on Matlab or Mathematica.

Some background reading: Wikipedia Article on Anyons; Wikipedia Article on Topological Quantum Computing; Steven Simon (2010) “Physics World: Quantum Computing with a Twist” (see my home page for link); Ady Stern (2008), “Anyons and the quantum Hall effect

— A pedagogical review”. Annals of Physics 323: 204; Chetan Nayak, Steven Simon, Ady Stern, Michael Freed-man, Sankar Das Sarma (2008), ”Non-Abelian anyons and topological quantum computation,” Reviews of Modern Physics 80 (3): 1083.Supervisor: Prof S Simon Email: s.simon1@physics.ox.ac.uk

TP10 Topological Statistical Mechanics

Exactly solvable models have taught us an enormous amount about statistical physics and phase transitions. A new class of (classical) stat-mech models was recently proposed which can be solved exactly due to their having a special “cross-ing” symmetry. The simplest example of such a problem is counting the number of nets (branching tree structures) without ends on the honeycomb.

The objective of this project is to use the exact solvabiltiy of these models as a stepping off point for the analysis of models which are nearly, but not exactly, solvable. I.e., we will perturb these models with small terms that slightly ruin the crossing symmetry. We will use several tools to come to an understanding on the statistical physics of these sys-tems — these tools include numerical simulation of several types, analytical perturbation theory, and renormalization group approaches.

The project is suitable for a mathematically strong student taking the Theoretical Physics option. This work will involve analytical calculations, and a large component of computer programming. Working knowledge of a compu-tational programming language such as C, C++, or fortran will be required.

Some background reading: Steven H. Simon, Paul Fendley; J. Phys. A 46, 105002 (2013). M. Hermanns and S. Trebst http://arxiv.org/abs/1309.3793.Supervisor: Prof S Simon Email: s.simon1@physics.ox.ac.uk

TP11 Fractional Quantum Hall Effect

One of the most spectacular experimental discoveries of condensed matter physics is the fractional quantum Hall ef-fect — an effect that occurs to electrons at low temperature in two dimensional semiconductor devices in high mag-neticfields.Undertheseextremeconditions,electronscanfractionalize to form quasiparticles having only part of the elementary electron charge.

What is perhaps even more remarkable about this effect is how well we understand it. The basics of the effect can all be summarized by one delightfully simple analytic wavefunction which, although approximate, very accurately describes the real systems. Numerical calculations involving this type of trial wavefunctions are possible and are viewed as extremely reliable.

The objective of this project is to learn about fractional

quantum Hall physics and to begin performing monte-carlo style calculations that will make predictions for real experi- ments.

The project is suitable for a mathematically strong student taking the Theoretical Physics option. This work will in-volve a great deal of background reading and a large com-ponent of computer programming. Working knowledge of a computational program- ming language such as C, C++, or fortran will be required.

Some background material: Wikipedia article on Fraction-alQuantumHallEffect;ArticlebySteveGirvinhttp://www.bourbaphy.fr/girvin.pdf;arxiv.org/pdf/cond-mat/9907002;Book by R. Prange and S. Girvin, “The Quantum Hall Ef-fect” (do yourself a favor and skip the chapter by Pruisken) Book by Tapash Chakraborty and Pekka Pietilainen, “The Quantum Hall Effects”.Supervisor: Prof S Simon Email: s.simon1@physics.ox.ac.uk

TP12 Topics in Geometry and Gauge/String Theories

We present the student with a manageable (appropriate for a mathematically and theoretically inclined fourth-year), self-containedprojectinaspecificproblemintherealmoftheinteractionofgeometryandgauge/stringtheory.

Topicshaveincludedfinitegraphsandfieldtheory,Calabi-Yaumanifolds and compactification, aswell asmoderngeometrical aspects of the standard model from string theory.

The project will provide an opportunity for the student to somerudimentsof,forexample,differentialgeometry,field/string theory and advanced algebra.

Someprogrammingexperience(withCandmathematica/maple) most welcome.Supervisor: Dr Y-H He Email: y.he1@physics.ox.ac.uk

TP13 Designing synthetic molecular motors

A most fascinating aspect of the busy life in a living cell is active transport. In the nanoscale world where thermal agitations are wild, miniature machines called molecular motors convert chemical energy – by breaking down ener-getic molecules - directly into useful mechanical work, in theformofcarryingcargoorslidingmusclefibresagainstone another. These molecular machines are remarkable and incrediblycomplicated.Whileitwillbedifficulttoimaginefabricating such sophisticated machines in the lab, one would naturallywonderifitispossibletodesignmoresimplifiedmachines with similar functionalities.

We aim to construct a simple model that is equipped with a catalytic mechanism to extract free energy from the break-down of certain fuel molecules and actuate the required shape changes using electrostatic interactions. The motor will have enzymes on board, which catalyze chemical reactions that involve ionic products. This allows the system to convert a biochemical cycle to a mechanochemical cycle, and develop a chemically powered molecular-scale actuation mechanism. When the ions are still attached to the enzymes, electrostatic interaction between them and other charged elements of the motor can lead to conformational changes. We aim to study how such a motor could stochastically walk along a solid

substrate, which would have the right complementary charge pattern to allow for a processive movement of the motor. The stasticial physics will be built into the study using master equations, and the Langevin dynamics formalsim. The model will be studied analytically and numerically.Supervisor: Prof R Golestanian Email: r.golestanian1@physics.ox.ac.uk

TP14 Twitching motility of bacteria near surfaces

Bacteria move around using all kinds of ingenius mecha-nisms, and have an astonishing ability to adapt their motil-ity strategy to the physical conditions of the environment. A number of bacteria (such as Pseudomonas aeruginosa) utilise a strategy that is termed as twitching motility, when they are settled on solid surfaces. This essentially amounts tocatapultingmanymicroscopicmusclefibresalongrandomorientations until they hit a suitably stirdy anchor point, “measuring up” how things are along each of these, and deciding which way is best to proceed by pulling a bit more ontherelevantmusclefibreandperhapsbreakingoffoneortwofibresattheback(thatwillberetractedandpreparedfor the next catapult shot).

We aim to study this process by constructing a simple mechanical model that has the right ingredients in terms of the dynamics (elasticity, friction, noise), and examining analytical and numerical solutions of the simple dynamical equations (Langevin dynamics).Supervisor: Prof R Golestanian Email: r.golestanian1@physics.ox.ac.uk

TP15 Orbits of globular clusters

The project involves using the latest data for the locations and velocities of globular clusters and a new mass model of our Galaxy to compute the actions that characterise each cluster’s orbit through the Galaxy. If time allows, one could examine the impact of tides on the cluster’s internal dynamics.

An ability to program will be necessary.Supervisor: Prof J Binney Email: j.binney1@physics.ox.ac.uk

TP16 Spiral structure using perturbation particles

Conventional N-body simulations of stellar systems are severely limited by Poisson noise. The method of perturbation particles (MNRAS 262, 1013) overcomes this limitation by using particle to represent only the difference between a perturbed model and an analytic equilibrium. To date this technique has been little used for lack of appropriate analytic models. In this project perturbations of models similar to those described in arXiv1402.2512 will be followed by perturbation particles.

An ability to program in C++ will be a distinct advantage.Supervisor: Prof J Binney Email: j.binney1@physics.ox.ac.uk

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TP17 & 18 Understanding the biophysics of DNA nano-structures

The ability to design nanostructures which accurately self-assemble from imple units is central to the goal of en-gineering objects and machines on the nanoscale. Without self-assembly, structures must be laboriously constructed in a step by step fashion. DNA has the ideal properties for a nanoscale building block, and new DNA nanostructures are being published at an ever increasing rate. Here in the Clarendon the world-leading experimental group of Andrew Turberfieldhascreatedanumberofintriguingnanostructuresusing physical self-assembly mechanisms. We have recently developed a new theoretical model of DNA that is complex enough to capture the dominant physics involved, but sim-ple enough to be tractable In this project you would apply the model to study physics of a simple nanostructure. You will mainly be using computer simulations and theoretical calculations to study these processes. You can read more at http://dna.physics.ox.ac.ukSupervisors: Dr A A Louis Email: a.louis@physics.ox.ac.uk

Index

AAllen, Prof Myles 21Aplin, Dr Karen 18, 34, 35

BBaird, Dr Patrick 12Balbus, Prof Steve 24, 43Barr, Prof Alan 41Bartolini, Dr Riccardo 40Barz, Dr Stefanie 11Bell, Prof Tony 33Berry, Dr Richard 26Biller, Prof Steve 38Binney, Prof James 45Blockley, Dr Nicholas 34Blundell, Prof Stephen 28Boothroyd, Prof Andrew 29Bortoletto, Prof Daniela 38Bowles, Dr Neil 19Bulte, Dr Daniel 34

CCappellari, Dr Michele 22Carboni, Dr Elisa 17Christensen, Dr Matthew 14Clarke, Dr Fraser 22Coldea, Dr Amalia 31Coldea, Dr Radu 32Contera, Dr Sonia 26Corner, Dr Lorna 12Cotter, Dr Garret 35

DDavies, Prof Roger 22Devriendt, Dr Julien 24Donaldson Hanna, Dr Kerri 19Doucas, Dr George 40Dudhia, Dr Anu 13

EEggeling, Dr Christian 26

FFoot, Prof Christopher 12, 35

GGolestanian, Prof Ramin 45Grainger , Dr Don 13, 14, 15, 17Gray, Professor Lesley 13Gregg. Prof John 33, 35Gregori, Dr Gianluca 10Guenette, Dr Roxanne 37

HHays, Dr Chris 38He, Dr Yang-Hui 45Henry, Dr Sam 35, 39Herz, Prof Laura 30Hesjedal, Dr Thorsten 29Huffman, Dr Todd 40Hurley, Dr Jane 19

I

JJaksch, Prof Dieter 12Jarvis, Dr Matt 24John, Dr Malcolm 39Johnston, Dr Michael 30Juricke, Dr Stephan 17

KKapanidis, Dr Achillefs 26Karastergiou, Dr Aris 23Karenowska, Dr Alexy 27, 28, 33, 35Khatiwala, Dr Samar 18Kipling, Dr Zak 15Konoplev, Dr Ivan 40Kraus, Prof Hans 38Kuhn, Dr H Axel 11

LLabbouz, Dr Laurent 16Lawrie, Mr Scott 40Leek, Dr Peter 30Lintott, Dr Chris 22Lopez, Dr Eduardo 36Louis, Dr Ard 46Lucas, Dr David 10Lynas-Gray, Dr Tony 25

MMacleod, Dr David 21Marshall, Prof David 18McGarragh, Dr Gregory 15Miller, Prof Lance 25

NNickerson, Dr Richard 35Norreys, Prof Peter 10, 11

OOsprey, Dr Scott 20Otto, Dr Friederike 21

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PPalmer, Prof Tim 14, 15Partridge, Dr Mike 34Peskett, Dr Guy 36Porter, Dr Mason 42Potter, Dr Will 22Povey, Dr Adam 13Prabhakaran, Dr Dharmalingam 29Princep, Dr Andrew 33

RRead, Prof Peter 19, 20Reichold, Dr Armin 38, 39Richardson, Dr Mark 23Riede, Dr Moritz 30Rojo, Dr Juan 42Ryder, Mr Nicholas 39

SSchekochihin, Dr Alexander 24, 43, 44Schoenrich, Dr Ralph 42, 43Scovell, Dr Paul 39Simon, Prof Steve 44, 45Simpson, Dr Robert 25Sloan, Dr David 22Slyz, Dr Adrianne 24Smith, Dr Brian 12Snaith, Dr Henry 32Steane, Prof Andrew 12Stier, Prof Philip 15, 16Subramanian, Dr Aneesh 15Suggit, Dr Matthew 28

TTaylor, Prof Robert 27Terquem, Dr Caroline 24Tseng, Dr Jeff 37, 38Tucker, Dr Stephen 26Turberfield,ProfAndrew26

VViehhauser, Dr Georg 39

WWalmsley, Prof Ian 11Wark, Prof Justin 12, 28Watson, Dr Peter 14Weber, Prof Alfons 39Weidberg, Dr Tony 37Weisheimer, Dr Antje 21Wells, Dr Andrew 17Woollings, Dr Tim 14

YYassin, Prof Ghassan 36

ZZanna, Dr Laure 18

Project Allocation: CHOICE FORMPlease make your 8 project choices. It is important that you list your choices in order of preference, 1 being the highest and 8 lowest. Each project is listed using its own unique project number, e.g. AS01.

If you wish to add any further information to assist in the allocation process please add a brief comment to the back of this form. You will be contacted by e-mail if you are required to make further choices.

Are you doing Physics and Philosophy?...............................................................................................................

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Return the form to the Physics Teaching Faculty, Clarendon LaboratoryDeadline: Friday 6th week, 3.00 pm of Trinity Term 2015

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MPhys Project

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Appendix A