Detector R&D Projects
Development of sensors and novel technologies for particle detection in HEP and beyond.
Contact: Stephen Wotton or Bart Hommels
See also: Cambridge Detector R&D homepage
Prospective students with a keen interest in hands-on practical work are invited to contact us to discuss possibilities in this area. The HEP group has a strong track record in the development of extremely radiation-hard silicon sensors with O(10 um) resolution for tracking and single-photon position-sensitive devices for Ring Imaging Cherenkov (RICH) Detectors. In addition, a new detector R&D activity to develop Resistive Plate Chamber (RPC) detectors for large-scale precise-timing applications, like the proposed ANUBIS experiment, is being set up. Projects may include the development, refinement or upgrade of existing detectors such as these or may focus on the development of more speculative techniques for use in future experiments. Examples of current projects are the development of a RICH detector prototype using solid state sensors or the application of the ATLAS silicon tracking technology to areas beyond the field of High Energy Physics.
Although focussed on detector research and development, there would also be an opportunity to analyse data from running experiments or data taken at beam test facilities.
Characterisation of novel radiation-hard semiconductor sensors.
Contact: Bart Hommels or Paula Alvarez Cartelle or Matt Kenzie
See also: Cambridge Detector R&D homepage
An upgrade of the tracking system to novel sensors with unprecedented radiation-hardness would allow to harvest significantly more data with the LHCb experiment at the High-Luminosity LHC. This is key to cast the ultimate judgement on the indications of a potential lepton flavour universality violation seen by LHCb physicists. The upprecedented radiation hardness can be achieved with novel CMOS sensor technology. With the first release of CMOS sensor prototypes foreseen in Q2 2022, the Cambridge HEP group offers an exciting opportunity to get involved in the characterisation of these early prototypes. To establish the performance of the sensors, the key areas that need probing are the intrinsic, sub-ns timing resolution of the sensors, their charge collection efficiency and the corresponding pulse height characterisics. Comparative studies will be made to study the performance degradation of sensors due to radiation damage accumulations during their operation in the LHC. Sensor samples irradiated with protons, neutrons and gamma photons are to be subjected to studies using advanced techniques such as Transient Current analysis of laser or fast electron induced signals. Advanced device simulation techniques (TCAD) will be used to cross correlate experimental results with predicted outcomes to assess end-of-life performance figures for operation in the HL-LHC. (back to top)
ATLAS Projects
ATLAS upgrades, and searches for things beyond the Standard Model in ATLAS
Contact: Chris Lester
See also: Cambridge ATLAS homepage
The Higgs Boson discovery, while interesting, was really part of "old", very much expected physics. The ATLAS detector has, so far, found no traces of "new" physics: supersymmetric particles, extra dimensions, and so on, despite many searches. Given this situation, phenomenologists need to be sure that all possible search strategies are covered. In the last three years Cambridge ATLAS has used established search methods to look for supersymmetry and black holes. However, a recent discovery of what appears to be an entirely new way of looking for R-parity violating supersymmetry encourages the Cambridge BSM team to focus the coming year’s efforts on developing that new technique. Cambridge ATLAS is also working on two separate upgrade projects (one in the next ATLAS tracker, one in the calorimeter trigger) that will need increasing support over the next four years. A student pursuing a PhD based on BSM searches could potentially use it as an opportunity to gain some experience of detector design and/or operation, thereby increasing his or her future employability. We therefore welcome applications from students who believe they might be able to inject similar creativity into the field of BSM searches, a field which otherwise is perhaps ripe for being shaken up after a period in which it has seen little innovation, and those who might like to combine that with detector work.
In order to become an ATLAS author, new collaboration members have to complete a technical project during their first year. Students will be able to work in a variety of areas, including software and simulation for the ATLAS Level-1 calorimeter upgrade , work on upgraded data-acquisition software for the next generation tracker. (back to top)
Hunting for Dark Matter in ATLAS
Contact: Tina Potter
See also: Cambridge ATLAS homepage
Dark Matter is one of the most compelling mysteries of modern-day physics. With no suitable candidate in the Standard Model of particles, new physics is needed to explain the 26% Dark Matter in our universe. Supersymmetry (SUSY) offers a potential solution by introducing many new particles, the lightest of which is an excellent Dark Matter candidate. Discovering new physics such as SUSY is a major goal of the ATLAS experiment at the LHC, and a focus of the Cambridge HEP group. However, the lack of a discovery to date tells us that SUSY may not be easy to find. If SUSY particles are close in mass, the experimental signature can be very difficult to separate from the Standard Model processes. My current targets include the superpartners of tau-leptons (staus), as well as charginos and neutralinos. A student could identify areas of SUSY parameter space where ATLAS does, and more importantly, doesn't yet have sensitivity, and design searches to address these uncovered areas. The PhD project(s) would use the full 13.6 TeV dataset from the ongoing Run 3, as well as from Run 2 taken in 2015-18, to search for signs of new physics, using modern multivariate selection techniques, such as artificial neural nets and boosted decision trees. (back to top)
Contact: Oleg Brandt
See also: Cambridge ATLAS homepage, Cambridge ANUBIS homepage
The particle nature of Dark Matter, which accounts for 4/5 of the Universe, is one of the biggest questions in Elementary Particle Physics today. The Large Hadron Collider (LHC) provides an unprecedented possibility to search for Dark Matter particle production in a controlled laboratory environment. One of the major goals of the Cambridge HEP group is to explore this opportunity using the ATLAS detector and its proposed extensions like the ANUBIS detector, targeting striking detector signatures involving new particles with microscopic lifetimes, i.e., long-lived particles (LLP). This search strategy is strongly motivated by a large class of theories suggesting anomalous couplings of the Higgs boson to massive Dark Sector particles and would aim to close sensitivity gaps highlighted in our recent review "Collider Searches for Dark Matter through the Higgs Lens".
Run 3 of the LHC, which started in 2022, opens a 'golden era' for LLP searches:
it is now possible to trigger the recording of events with new exotic LLP signatures for the first time at ATLAS, which we aim to exploit by devising new trigger algorithms and analysing the corresponding data. We also aim to study the senstivity of future detectors like ANUBIS to such LLP signatures. A doctoral research project would explore these novel LLP search strategies at the LHC.
The project will suit someone who is keen to analyse LHC data and/or who is keen to optimise the design of future detectors. (back to top)
Supersymmetry searches and precision measurements
Contact: Sarah Williams
See also: Cambridge ATLAS homepage
As well as searching directly for the production of new particles predicted in extensions to the Standard Model (SM) precise measurements of SM processes can provide indirect tests that could be sensitive to new particles at mass scales much higher than those that can be probed directly. The run 3 dataset collected by the ATLAS experiment will enable measurements of rare SM processes not previously observed experimentally as well as larger datasets that can be used to perform SM measurements in more extreme decay topologies inspired by searches. The PhD student would join a new programme in the ATLAS supersymmetry working group that aims to bridge the gap between searches and measurements. In the early years the student would work on the design and implementation of new searches for dark matter inspired supersymmetric models, and would later contribute to the production of precision SM measurements associated with the search
The project will suit someone who is keen to analyse LHC data. (back to top)
LHCb Projects
Measurement of matter-antimatter asymmetries in B decays
Contact: Matt Kenzie
See also: Cambridge LHCb homepage
The fact that we live in a Universe made of matter (and no antimatter) is extremely puzzling since, shortly after the Big Bang, matter and antimatter should have been produced in equal amounts. The phenomenon responsible for matter-antimatter asymmetries is called CP violation (a violation of the charge-parity symmetry between matter and antimatter). Observation of CP violation is now well established and is accommodated in a three generation Standard Model by Cabibbo-Kobayashi-Maskawa (CKM) quark-mixing matrix. However, the amount of CP violation we see in the CKM matrix (which is the only place we have ever seen CP violation) is many orders of magnitude too small to account for the matter-antimatter asymmetry we see in the Universe (from cosmological observations). Therefore, we know there must be new sources of CP violation which requires physics beyond the Standard Model. The project will include analysis of all LHCb data taken at the highest LHC centre-of- mass-energy from the start to the current date. The focus of the project will be to exploit B meson decays, such as B → DK or B → KK, which have exquisite precision to CP violating phases such as γ and ϕs. Comparison between these measurements and the SM predictions allow us to probe for New Physics phenomena at much higher energy scales (at the 10s-100s TeV scale) than are accessible by direct production. Studentships are available through the ERC funded “KstarKstar” project and via normal STFC funding routes. Students would join a small team of other PhD students and post-doctoral researchers based in Cambridge, along with international collaborations via CERN. Short-term and long-term stays at CERN are foreseen, although not mandatory.
The project will suit someone who is keen to analyse LHC data. (back to top)
Search for New Physics beyond the Standard Model in rare B decays
Contact: Paula Alvarez Cartelle
See also: Cambridge LHCb homepage
The Standard Model of particle physics is a well established monument. However, New Physics beyond the Standard Model is necessary to describe the mass hierarchy of fundamental particles. The LHCb experiment, running at the Large Hadron Collider at CERN, is particularly well suited to look for indirect evidence of New Physics using quantum loop processes. These include rare decays, such as Bd,s → mumu and Bd → K0*mumu decays, and searches for lepton-flavour violation by combining the information from several decays e.g. Bd → K0*mumu and Bd → K*ee. The huge volume of data collected by LHCb allows for a precision measurements of the decay rates, effective lifetimes and angular observables, which measure the intimate properties of these decays. In turn, the measurements are used to constrain New Physics models. This indirect model-independent approach is very powerful, and is crucial since New Physics still evades detection. The project will include the analysis of all data taken by LHCb from the start to the current date.
The project will suit someone who is keen to analyse LHC data. (back to top)
Neutrino Physics Projects
Understanding Low Energy Neutrino Oscillations at MicroBooNE
Contact: Melissa Uchida
See also: Cambridge MicroBooNE homepage
The MicroBooNE neutrino experiment at Fermilab USA, utilises a large liquid Argon (LAr) time projection chamber (TPC), which allows "photograph quality" images of the particles produced in neutrino interactions in the MicroBooNE detector. The recorded events contain a wealth of information and Cambridge is playing a leading role in the automated reconstruction of these images using advanced pattern recognition software as well as in the analysis of MicroBooNE data. MicroBooNE has 5 years of data to analyse with all current results based on the first 50% of this data. This is therefore a great time to get involved in the next generation of analyses.
MicroBooNE is investigating the low energy excess of electron-neutrino-like events appearing from a muon-neutrino beam above oscillation expectation, which was observed by both the MiniBooNE and LSND experiments. The most likely BSM causes of this anomaly along with the most likely background explanation have been ruled out by the first round of MicroBooNE analyses. Therefore, understanding this excess has become more interesting than ever as, whatever the cause, it is more interesting than we thought... MicroBooNE also measures a suite of low energy neutrino cross sections on argon for the first time (which is vital to the success of the next generation of neutrino experiments at Fermilab.
The PhD project is to work on MicroBooNE data analysis and potentially in the development of pattern recognition software for LAr-TPC detectors. This project represents an exciting opportunity to work on the first large LAr detector in an intense neutrino beam. There will also be the opportunity to work on MicroBoonE alongside DUNE and protoDUNE, thereby gaining experience of long and short baseline experiments at various stages of operation. (back to top)
Contact: Melissa Uchida
See also: Cambridge DUNE homepage
The Deep Underground Neutrino Experiment (DUNE) is a cutting-edge experiment for neutrino science. Its physics programme includes: neutrino oscillation physics, CP violation searches, measuring the neutrino mass hierarchy, proton decay studies as well as astrophysics and beyond the standard model physics searches.
DUNE will consist of two suites of neutrino detectors placed in the world’s most intense neutrino beam. The "Near detector" suite will record particle interactions near the source of the beam, at the Fermilab, Illinois. A second, much larger 40,000 ton "Far" detector will be installed more than a kilometer underground at the Sanford Underground Research Laboratory in Lead, South Dakota — 1,300 kilometers downstream of the neutrino source. These detectors will enable us to search for new subatomic phenomena and potentially transform our understanding of neutrinos and their role in the universe. DUNE is currently under construction.
This project represents an exiting opportunity to work on this cutting-edge neutrino experiment, being one of the first to develop the techniques and indeed the hardware which DUNE will use to answer the biggest questions in the neutrino physics today. The project will involve working across hardware, software, and reconstruction as well as preparing for first physics analysis. There will also be the opportunity to be involved in data analysis of the MicroBooNE Low Energy Neutrino Oscillation Experiment at Fermilab and the protoDUNE detectors at CERN. ProtoDUNE is a large-scale prototype for DUNE long-baseline neutrino oscillation experiment and has been taking data since 2018. (back to top)
Ultralight Dark Datter and Gravitational Waves Projects
Search for ultra-light dark matter using novel atom interferometers (MAGIS and AION)
Contact: Val Gibson
Next generation atom interferometers, MAGIS (Fermilab, US) and AION (UK), will enable searches for ultra-light dark matter and provide a pathway towards detecting gravitational waves from astrophysical sources in the yet unexplored mid-frequency band (several mHz to a few Hz). Atom interferometry in this frequency range has the potential to explore dark matter with unprecedented sensitivity over a large mass range (10^-13 to 10^-23 eV), and open a new window on the cosmos that lies between the Advanced LIGO and LISA experiments.
A student joining the HEP group on the MAGIS and AION projects will have a unique opportunity to participate in two new international, multi-disciplinary projects that utilize the Cavendish’s expertise in cold atoms (Dr Ulrich Schneider’s research group) and connect the fundamental research areas of particle physics and gravitational wave physics. Within the next 3 years, MAGIS will have taken first data. The research project will include full participation in the construction, commissioning, operation and analysis of data from MAGIS. In particular, the project will include the development of the readout, controls and monitoring, as well as the development of the timing and controls synchronisation to network the MAGIS and AION interferometers thereby providing a gateway to the full potential of the MAGIS and AION physics programs. The project will also serve as a testbed for full-scale terrestrial (km-scale) and satellite-based (thousands of kms scale) detectors and builds the framework for global scientific endeavour for the future.
This project will suit someone with a keen interest in (currently) small-scale particle physics experiments, with computing, electronics, machine-learning and physics analysis research skills. (back to top)
Theory Projects
Theory Beyond the Standard Model at the Large Hadron Collider
Contact: Ben Gripaios
This project will focus on the development of candidate theories of new physics, going beyond the Standard Model (SM). Such physics is needed to solve consistency problems within the SM itself, as well as to describe various observed phenomena that do not have an explanation in the SM.
These include the Dark Matter and Dark Energy in the cosmos, the hierarchy between the electroweak scale and higher energy scales in physics (for example the scale of quantum gravity), the excess of matter versus antimatter that allows us to be here, the number of families of quarks and leptons and the patterns of their masses and mixings, the masses of neutrinos, the apparent unification of gauge interactions, the absence of CP violation in the strong interactions, and more.
Recent research within the group has addressed all of these questions. The challenge is to come up with a theory that extends the SM and which explains some or all of these phenomena, without being in conflict with the many other observations that are consistent with the SM alone. With such theories in hand, one can look for novel experimental signatures, which can be searched for at the LHC and elsewhere. (back to top)
Contact: Ben Gripaios
Recently it has been shown that there is a consistent quantum field theory (QFT) description of an ordinary classical fluid. This theory is very different from the other QFTs tha are now ubiquitous in high energy physics and elsewhere, because of the presence of fluid vortices. The project will focus on studying the quantum analogues of classical fluid mechanics phenomena, such as vortices, shocks, surface waves, and Kelvin waves, and in searching for evidence of this behaviour in real-world systems. (back to top)
Precision Standard Model Physics at the Large Hadron Collider
Contact: Alex Mitov
Both LHC measurements and Searches for Physics Beyond the SM at the LHC require predictions for observables computed within the SM. Calculations of SM observables with high-precision is within the current cutting-edge of particle physics research. The main goal of this project is to develop new methods for performing such calculations for processes never computed before, as well as applying these calculations to cutting-edge phenomenology. The project will lead to deep understanding of multi-loop calculations in Quantum Field Theory and to the development of sophisticated software which implements these ideas into practical predictions. (back to top)