PhD projects Offered
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Experimental: Vector boson measurements with ATLAS
PhD project: Measuring WZ events in the semi-leptonic channel using ML-based taggers
Supervisor: Prof.Mario Campanelli
Several new physics models predict particles that interact with vector bosons, notably W and Z bosons.
Albeit measurements of WZ production already exist in ATLAS,
they are not optimised to the kinematic regime that could indicate presence of new physics.
This project aims at measuring the production of W and Z boson in the case when one of them
decays in the clean leptonic channel, and the other in the hadronic one,
giving rise to a hadronic jet with characteristic 2-prong signature.
These decay modes are identified using specific Machine-Learning based algorithms,
that have been developed by the UCL group and other collaborators over the years.
During the course of this project the student will work on further improvements
and in the design of new techniques for multi-particle tagging.
The final results will be interpreted in the context of various new physics models,
and unfolded to particle level using modern ML-based techniques.
The student will be expected to spend an extended period (up to 1 year) at the CERN laboratory in Geneva.
Contact: Prof. Mario Campanelli
Experimental: Anomaly detection with ATLAS
PhD project: Anomaly detection in ATLAS using machine learning
Supervisor: Prof. Mario Campanelli
After over a decade of unsuccessful searches for new physics at the LHC, the attention is shifting more and more towards model-independent approaches that exploit the rapid advancement of machine learning from last years. Detecting anomalies means searching for events that differ from the bulk of Standard Model collisions recorded by the detector, in a novel and model-independent way. Instead of searching for a specific model of new physics, the events are classified into classes using unsupervised techniques, mapping the emitted particles to a lower-dimensional space the various regions corresponding to known physics identified using Monte Carlo simulations. Anomalous events laying outside of the known boundaries may indicate unforeseen phenomena. The work will also explore the possibility to perform this searches online at trigger level, for the high-luminosity upgrade program.The student will be expected to spend an extended period (up to 1 year) at the CERN laboratory in Geneva.
Contact: Prof. Mario Campanelli
Experimental: Searches for Dark Sector with ATLAS
PhD project: Unconventionally dark
Supervisor: Prof. Andreas Korn
The search for physics beyond the standard model is still at full swing at the Large Hadron Collider. While new particles cannot be guaranteed, it seems at least one is clearly missing, a candidate for dark matter. Viable models will need to be looked for using unconventional signatures. In particular long-lived particles (LLP) decaying late in the detector. This project will look for LLPs makeling use of the expertise of the UCL group on tracking and advanced methods to identify such particles.The student will have the possibility to spend an extended period (up to 1 year) at the CERN laboratory in Geneva.
Contact: Prof. Andreas Korn
Experimental: Establishing the "Isolated Standard Model" with ATLAS
PhD project: Establishing the Isolated Standard Model with ATLAS
Supervisor: Prof. Jon Butterworth
Historically, substantial increases in the energy scale we can probe have revealed new phenomena. The ATLAS experiment is measuring new physics processes above the electroweak symmetry-breaking scale, extending our precision and reach at the energy frontier. Because the Higgs boson exists, the Standard Model is capable of precise predictions in these new regimes. The key question is - how successful are these predictions? Does the physics developed at lower energies continue to work at high energies - in other words, is the Standard Model "isolated", in the sense that the new phenomena we know must exist lie far away, either in coupling strength, energy scale or both. Or will these measurement reveal physics such phenomena? This project will tackle the question by joining the measurement programme at ATLAS, and using the UCL-developed "Contur" programme to compare the data to state-of-the-art predictions from the Standard Model and beyond.Contact: Prof. Jon Butterworth
Experimental: Neutrinoless double-beta decay with LEGEND
PhD project: LEGEND Neutrinoless Double-Beta Decay Experiment
Supervisor: Prof. David Waters
Neutrinoless double-beta decay (0vbb) is a process often predicted in theories of physics beyond the Standard Model. Two electrons are produced in the decay process but no neutrinos are emitted: in effect a neutrino is created and re-absorbed inside the nucleus, and this can only happen if they are Majorana particles. The 0νbb process is manifestly lepton number violating, and would shine a light on the mechanism underlying the cosmological matter-antimatter asymmetry that we observe today.The most sensitive experiment in the world searching for 0νbb is LEGEND, using high-purity germanium (HPGe) solid-state detectors fabricated with the double-beta isotope Ge-76. The first phase of LEGEND, using 200kg of isotope, has now started taking data at the Gran Sasso underground laboratory in Italy. Over the next few years, LEGEND has the potential to make a ground-breaking discovery of 0νbb, and the UCL group is at the forefront of the analysis effort.
A PhD project on the LEGEND experiment will include:
- Analysis of data from LEGEND-200, including the development of novel techniques to maximise the discovery potential of the experiment.
- Analysis of the performance and backgrounds of LEGEND-200, to inform the preparation of the next phase of the project (LEGEND-1000) that will be entering construction later this decade.
- The operation and development of HPGe detectors onsite at UCL.
Contact: Prof. David Waters
Experimental: Plasma wakefield acceleration at FLASHForward
PhD project: Plasma Wakefield Acceleration on the FLASHForward Experiment
Supervisor: Prof. Matthew Wing
A studentship is offered jointly funded by DESY and UCL to work on plasma wakefield acceleration which could lead to future machines that are shorter and less costly than when using conventional accelerator techniques. The student will work on the FLASHForward experiment at DESY which is investigating electron-driven plasma wakefield acceleration. Research at the FLASHForward experiment focuses on energy gain of witness electron bunches, their beam quality, efficiency of the process, etc. The student would work on understanding the repetition frequency of the acceleration process, crucial to the luminosity of future colliders or brightness of future light sources. Up to megahertz rates are required and the dynamics of the plasma and beams needs to be understood in detail for a range of parameters with a combination of experiment and simulation. The student would also have the opportunity to work on designs for future colliders such as the recently proposed HALHF collider. The student would spend a significant period of about 2 years based in DESY, Hamburg, working directly on the experiment and closely with the rest of the collaboration. Contact: Prof. Matthew WingExperimental: Novel integrated detectors for Proton Beam Therapy
PhD project: The QuADProBe - A Quality Assurance Detector for Proton Beam Therapy
Supervisor: Prof. Simon Jolly
Proton therapy is a more precise form of radiotherapy that provides significant benefits over conventional X-ray radiotherapy, particularly for children. Two new detectors currently under development within the HEP proton therapy group are focussed on improving Quality Assurance (QA) in proton therapy, but have applications in patient positioning and imaging. All of these applications will assist in making proton therapy safer and more accurate for patients as well as allowing more patients to be treated through saved QA time. The QuARC measures the proton range with a series of plastic scintillator sheets. The scintillation light output is measured by a series of photodiodes, which are read out by custom ADC boards controlled by an FPGA. The QuADProBE adds beam size and position through orthogonal arrays of scintillating fibres, again read out by photodiode arrays and controlled by FPGA.This project focuses on the development of the QuADProBe, with the inclusion of a detector capable of measuring dose. The intention is to include dose measurements to the final clinical system, thereby providing a single detector capable of making all 4 clinical beam QA measurements at once: this would be the first such clinical system. The project will cover the development of the dose monitor from a design from NPL, the front end electronics and data acquisition development and integration of the complete detector data acquisition system with the scintillating fibre readout. There will also be some web development required for the back-end detector control, which is entirely web-based. The student will be expected to accompany the PBT group on experimental runs to clinical facilities and be given the opportunity to learn clinical uses of proton beam therapy and observe patient treatment alongside the experimental work.
More details on the project can be found on the UCL HEP Proton Therapy page.
Contact: Prof. Simon Jolly
Experimental: Dark matter searches with LZ
PhD project: Dark Matter searches with the LZ and XLZD experiments
Supervisor: Prof. Chamkaur Ghag
Despite accounting for 85% of the mass of the Universe, the nature of dark matter remains a mystery. The LZ experiment, based at the Sanford Underground Research Facility, USA, is at the forefront in the quest to observe galactic dark matter, having recently published the world-leading limits on dark matter interactions. LZ is probing uncharted electroweak parameter space, with the ability to discover or provide constraints on the foremost dark matter theories. This studentship represents an exciting opportunity to participate in the analysis of science data from LZ. The candidate will play an active role in the flagship dark matter search, currently being led by the UCL group, and will have the chance to explore the sensitivity of LZ to more physics beyond the Standard Model, including neutrinoless double beta decay, also led by UCL. In addition to data analysis, the project will involve the use and development of Monte Carlo simulations and statistical inference techniques. There is the potential for the successful applicant to travel to site to assist in the operation of LZ’s 7 active-tonne dual-phase xenon time projection chamber, the world’s largest detector of its kind, as well as to spend extended time at one of our collaborating US, European, or Australian institutions. There will also be the opportunity to engage with design efforts and construction of XLZD, the future global xenon-based rare-event search observatory. XLZD will be the definitive WIMP search experiment, either delivering a historic first discovery, providing a high-statistics confirmation of signal in LZ, or definitively ruling out the standard WIMP hypothesis. XLZD also has immense potential as a rare-event observatory, enabling searches for alternative (non-WIMP) dark matter models, BSM physics inaccessible anywhere else, and neutrinoless double beta decay. Contact: Prof. Chamkaur GhagExperimental: Searching for new physics with Mu3e
PhD project: Searching for new physics with Mu3e
Supervisor: Prof. Gavin Hesketh
The search for physics beyond the Standard Model (BSM) is the defining aim of particle physics today, and precision muon measurements offer sensitivities to BSM far beyond the direct reach of the Large Hadron Collider. The Mu3e experiment will search for flavour violation in the charged lepton sector: lepton flavour violation has already been observed in neutrino oscillations, and is predicted in the charged lepton sector by a range of BSM models. Using an innovative, ultra low-mass tracker, Mu3e will perform the world's most sensitive search for the neutrinoless decay of an antimuon to two positrons and one electron, improve sensitvities by a factor of 10,000 over current limits and probing for new physics at mass scales beyond 1,000 TeV. This step-change in sensitivity brings the potential of a ground-breaking discovery when Mu3e begins data-taking in 2026. A PhD on Mu3e would involve: - a stay at the Paul Scherrer Institut (Switzerland), during Mu3e data-taking; - analysis of the first Mu3e data, including the optimisation of algorithms to increase the sensitivity, including the potential to deploy machine learning; - perform the first search for the three-electron signal, and explore the data for other potential signs of new physics. Contact: Prof. Gavin HeskethExperimental: New physics searches with Mu2e
PhD project: Searching for new physics with Mu2e
Supervisor: Dr Rebecca Chislett
Muons are a unique probe in the search for new physics, offering large increases in sensitivity that go beyond the reach of the Large Hadron Collider due to the availability of intense muon beams combined with the properties of muon production and decay. There are also hints that muons might behave differently coming from the g-2 experiment at Fermilab. One such experiment is the Mu2e experiment, also on the muon campus at Fermilab, which searches for charged lepton flavour violation (LFV) i.e. the direct conversion of a muon to an electron without neutrinos, in this case in the field of a nucleus, aiming for a sensitivity improvement of four orders of magnitude. LFV has been observed in the neutral sector in the form of neutrino oscillations but has not yet been observed in the charged sector, although it is predicted in a wide range of beyond the Standard Model theories. The rate allowed in the Standard Model is well below the level that experiments can currently reach so any observation would be a sign of new physics. This is an exciting time for the experiment as construction is nearly complete with commissioning starting in 2025, and data taking starting in 2026. A PhD would be ideally timed to contribute to both the commissioning of the experiment, and analysis of the first data taken by the experiment both with cosmics and first beam with a specific focus on the stopping target monitor, the detector system provided for the experiment by the UK.Contact: Dr Rebecca Chislett
Experimental: Absolute neutrino mass with Quantum Technologies
PhD project: Determining the absolute neutrino mass using quantum technologies
Supervisor: Prof. Ruben Saakyan
The absolute mass scale of neutrinos is one of the most important unknown quantities in physics. Neutrinos are the most abundant particles of matter in the universe and determining their mass will have the most profound implications for cosmology, astrophysics and for the theory of neutrino and other fermion masses. Existing laboratory techniques for direct measurement of the neutrino mass, such as KATRIN, cannot be extended beyond 0.2 eV, while the results from neutrino oscillations and the latest KATRIN upper limit indicate that he neutrino mass could be anywhere between ~0.01 and 0.45 eV. UCL is leading an experimental programme, Quantum Technologies for Neutrino mass (QTNM), that develops a technique that would overcome the current limitations using recent advances in quantum technologies to reach sensitivities at the order of 0.01-0.05 eV. In this approach tritium atoms will be confined in a magnetic storage ring and the energy of the electrons emitted in tritium beta-decay will be determined by measuring the frequency of EM radiation generated as a result of the electron’s cyclotron motion in a magnetic field. This technology is known as Cyclotron Radiation Emission Spectroscopy (CRES). UCL together with partner institutions is building a CRES Demonstrator Apparatus CRESDA. The main focus of the PhD project will be on commissioning, taking and analysing data of CRESDA that will inform a phased physics programme of QTNM ultimately aimed at the determination of the neutrino mass. CRESDA will use a source of electrons generated in a Penning trap that will be injected in the detection region and fully characterised. A low activity tritium run is also possible. The student will need to become an expert in a range of topics including quantum detection and amplification, microwave receiver physics and signal processing. The work will include a mixture of advanced detector development, including application of quantum sensors, and data analysis, with further studies on the physics potential of the experiment conducted at facilities such as the Culham Centre for Fusion Energy. Contact: Prof. Ruben SaakyanTheory: Advanced parton Showers
PhD project: Developing new Parton Shower tools
Supervisor: Prof. Keith Hamilton
Parton shower simulations are the most widely used theoretical tools in particle physics. Every LHC analysis, for example, heavily relies on their predictions. The PanScales project aims to provide the most accurate parton shower simulations to date. UCL is a core member of the PanScales team. The range of potential topics to study during a PhD on this project is broad, from novel phenomenological studies, to more formal QCD resummation theory, MC algorithm development, and computations to obtain ingredients for them. Such studies cover a range of possible activities, taking in conceptual theoretical work, computer-based symbolic calculation, numerics, C++ and HPC. Details of the PhD can be adapted to students' aptitudes and interests within the scope of the project. Contact: Prof. Keith HamiltonThere will also be 4-5 HEP studentship projects available via the Data Intensive Science (DIS) Centre for Doctoral Training (CDT) covering similar topics on a similar range of experiments. To be considered for these projects, an application will also need to be made directly to the CDT.