Physics thesis topics (for October 2020)

  1. Gravitational lensing of the cosmic microwave background
    • Supervisor: dr. hab. Paweł Bielewicz
    • Description: Gravitational lensing of the cosmic microwave background (CMB) is a relativistic effect caused by the gravitational interaction of the CMB photons with matter inhomogeneities encountered during their travel from the last scattering surface to an observer. Reconstructed from correlated CMB photon deflection angles gravitational potential of the lensing structures projected along the line-of-sight gives a unique image of the formation of the large scale structure at high redshifts and enables testing cosmological models at large scales. On the other hand, generated by the lensing effect divergence-free component of CMB polarisation has to be precisely estimated and corrected to be able to detect primordial gravitational waves produced during the inflationary epoch. This PhD project will involve research on different aspects of the CMB gravitational lensing effect including developing and implementation of algorithms for estimation of the gravitational lensing potential, modelling and simulations of the effect, cross-correlations with galaxy and radio surveys and correcting CMB maps for the lensing effect. The PhD student will analyse publicly available data from the Planck satellite and other ongoing and near future CMB experiments. The cross-correlation studies will be also realized within the framework of the Large Synoptic Survey Telescope experiment expected to begin observations in 2022. We seek strongly motivated PhD candidates with interest in cosmology who can demonstrate ability in programming and have experience in numerical methods.
    • Funding: NCBJ Fellowship
  2. New generation of gravitational wave detectors and its potential for testing cosmology and fundamental physics.
    • Supervisor: prof. dr hab. Marek Biesiada
    • Description: First detections of gravitational waves (GWs) by LIGO/Virgo collaboration opened a new window on the Universe. Following this ground-breaking achievement, GW community proposed a third-generation underground detector called the Einstein Telescope, which will have an order of magnitude better sensitivity than current detectors. This means that it would be able to probe three orders of magnitude greater volume of the Universe leading to an unprecedented statistics of GW sources originating at high redshifts. Moreover, there are advanced actions toward launching space-borne detectors LISA and DECIGO probing GW spectrum at low frequencies inaccessible from the ground. Their reach will be even bigger than the ET. Such concerted multifrequency coverage will elevate GW physics from weekly or monthly detections to a high-statistics era allowing high-precision astronomy and confronting the General Theory of Relativity with a plethora of experimental tests. Based on the Monte Carlo simulations of realistic forecasts of future GW data, the sucessful applicant will study the following issues: i) cosmological tests based on standard sirens using only observables obtainable from GW signals alone (i.e. without knowing the redshift of the source, but knowing its luminosity distance), ii) observational signatures of gravitational lensing of GW signals at low frequencies, iii) joint multifrequency observations of inspiralling binaries from the space and from the ground and their potential to directly probe the expansion of the Universe and testing theories violating Lorentz invariance.
    • Funding: NCBJ Fellowship
  3. Integrated risk assessment for combined nuclear and chemical facilities
    • Supervisor: prof. dr hab. Mariusz Dąbrowski
    • Description: This project concerns the most demanding problems on risk assessment for the chemical installations coupled with High or Very High Temperature Reactors (HTR/VHTR) optimized to the process heat production. Replacement of the coal or gas boilers by HTRs within the chemical plants requires, among others, considering the interactions between nuclear and non-nuclear parts of the installation, combined together in one complex system. Independently developed risk models for chemical and nuclear parts of such facilities would not describe properly the real state of the whole system and thus need to be integrated. The aim of the PhD work is to develop the overall risk assessment framework for combined nuclear and chemical facilities by taking into account the events posing a challenge for safety of the nuclear installation after failure of one or more chemical systems and vice versa. Within this framework there is a need for identification of the critical elements, the failure of which could lead to severe accidents as well as the accident sequences. Significant improvement of the current status of knowledge is expected in characterization of the risk associated with the physical phenomena and chemical processes applied in one part of the system (chemical or nuclear) in the context of fragility of the other one. This includes also proposition of the risk metrics for such installation. The framework for an integrated risk assessment will also provide methods for assessing the risks associated with external hazards as the potential threats for one or both (nuclear and chemical) parts of the installation. The project might be developed in collaboration with Japan Atomic Energy Agency (JAEA) operating the High Temperature Test Reactor (HTTR).
    • Funding: PhD4Gen project
  4. Nuclear Fuel Cycle studies of nuclear reactor fleet consisting of LWRs, HTGRs and other advanced reactors – development of the Nuclear Fuel Cycle Simulator – FANCSEE
    • Supervisor: prof dr hab. Wacław Gudowski
    • Description: In order to study material flow, material inventory, radioactivity and radiotoxicity of the final wastes in a nuclear power program it is obligatory to have a reliable and validated tool performing all necessary simulations. This PhD project is focused on development of an existing Nuclear Fuel Cycle Simulator FANCSEE which enables such simulations, but still requires a significant development. A candidate for such PhD project should have advanced skills in C++ programming and having good understanding of reactor physics and nuclear technology. Finally this simulator will be used for studying different scenarios of nuclear program development in Poland and other countries in order to optimize the costs of the back-end of the nuclear fuel cycle.
    • Funding: PhD4Gen project
  5. Multi-Physics Uncertainty Analysis of High Temperature Gas Cooled Reactor
    • Supervisor: prof dr hab. Tomasz Kozłowski
    • Description: The development of the High Temperature Gas Cooled Reactors (HTGRs) requires verification of HTGR design and safety features with reliable high fidelity physics models and robust, efficient, and accurate codes. The predictive capability of coupled neutronics/thermal-hydraulics simulations for reactor design and safety analysis can be assessed with sensitivity analysis (SA) and uncertainty analysis (UA) methods. Uncertainty originates from errors in physical data, manufacturing uncertainties, and modelling and computational algorithms. SA is helpful to partition the prediction uncertainty to various contributing sources of uncertainty and error. SA and UA is required to address cost, safety, and licensing needs and should be applied to all aspects of reactor multi-physics simulation. Current SA and UA rely either on derivative based methods, stochastic sampling methods, or on generalized perturbation theory to obtain sensitivity coefficients. The proposed project will develop and new hybrid multi-physics uncertainty method to quantify the impact of different sources of uncertainties on the design and safety parameters of HTGRs. Only a parallel effort in advanced simulation and in nuclear data improvement will be able to provide designers with more general and well-validated calculation tools to meet design target accuracies.
    • Funding: PhD4Gen project
  6. Deep and machine learning methods for searching for optical counterparts to gravitational wave events
    • Supervisor: prof. dr hab. Andrzej Królak
    • Auxiliary supervisor: dr Adam Zadrożny
    • Description: One of the hottest topics in today’s astronomy is searching and analyzing optical counterparts to gravitational wave events. Still there is only one such event observed, which is GW170817 / AT 2017gfo. It was observed during LIGO-Virgo Observing Run O2, which lasted 6 months and had one event that might plausibly produce optical counterpart. During O3 the third observing run there were more than 10 event that might have optical counterpart, but yet none was found. In order to make search more successful in upcoming LIGO-Virgo O4 science run (2022+) we would like to develop a strain of machine learning/deep learning methods for optical follow-up. The developed methods would be tested on TOROS collaboration telescopes during LIGO-Virgo O4 Observing Run. There is a possibility to expand scope of the project to electromagnetic data from POLAR-2 and LSST.
    • Funding: NCBJ Fellowship
  7. New samples for the analysis of neutrino oscillations in the T2K experiment
    • Supervisor: dr hab. Justyna Łagoda
    • Description: T2K is an experiment searching for neutrino oscillations and measuring cross-sections of neutrino interactions. The upgrade of T2K experiment includes changes in the Far Detector (Super-Kamiokande) and its calibration and reconstruction which allow to improve the detector performance and allow to better study the neutrino oscillations, aiming for observation of the CP violation for neutrinos. The student will work on the search and definition of the new samples of neutrino interactions for the oscillation analysis taking into account the present upgrades of the experiment. The candidate will collaborate with an international team of physicists; will present his/her work at local meetings in Poland and at collaboration meetings in Japan. It is possible to stay for training period in Japan during the doctoral studies.
    • Funding: NCN grant
  8. Study of neutrino interactions on correlated nucleon pairs in the T2K experiment
    • Supervisor: dr hab. Justyna Łagoda
    • Auxiliary supervisor: dr Joanna Zalipska
    • Description: T2K is an experiment searching for neutrino oscillations and measuring cross-sections of neutrino interactions. This project will be focused on investigations of interactions with correlated nucleon pairs, which are still not well known. The candidate will work on the analysis using (anti)neutrino data collected by the near detector of the T2K experiment and will contribute to work dedicated to the upgrade of that detector. The upgrade of the near detector is planned to be finalized in 2021. The student will contribute to the understanding of detection of low momentum particles. The candidate will collaborate with an international team of physicists; will present his/her work at local meetings in Poland and at collaboration meetings in Japan. It is possible to stay for training period in Japan during the doctoral studies.
    • Funding: NCBJ Fellowship
  9. Technical safety-related assessment of transmutation plant with liquid fuel (DFR)
    • Supervisor: prof. dr hab. Rafael Macian-Juan
    • Description: In the framework of this PhD work, safety-critical issues on the transient and accident behavior of transmutation plants are being examined in detail with the aid of the DFR system code(s) developed at TUM and NCBJ.  Based on event trees that take into account all significant component failures, transient analyzes, including startup and shutdown simulations and stability analyzes are performed, including consideration of the mechanical integrity of the component materials as a result of abnormal occurrence or accidents, i.e. possible (component) consequential damages of abnormal occurrence or accidents are to be estimated. The aim is to prove that the plant fulfills all safety requirements that are set within the scope of the licensing procedure. The work within the PhD project will be carried out in the following four steps.
      1. Compilation of the principles of safety design of the MSR/DFRs. Development of event trees, which are the basis for the transient analyzes to be carried out in the next work step.
      2. Performing transient analyzes based on the event trees in 1. These are simulations with the calculation codes provided by TUM/NCBJ.
      3. Critical analysis of the simulation results from 2. and estimation of possible consequential damages.
      4. Development of a clear presentation of the safety characteristics and comparison of the different reactor variants.
    • Funding: PhD4Gen project
  10. HELP to find Hot DOGs
    • Supervisor: dr hab. Katarzyna Małek
    • Description: The most luminous infrared galaxies in the universe are thought to be massive galaxies with intense star formation during a key stage in their evolution. They are also extremely dust-obscured which means that these objects are very bright in the IR but typically faint at UV/optical wavelengths. There are several populations of galaxies that are known to be in such stages, and one of them is the population of Hot Dust-Obscured Galaxies (Hot DOGs). Hot DOGs are characterized by very red mid-IR colours and by hot dust temperatures (T>60 K). In this topic of the PhD thesis, we plan to apply machine learning techniques to classify and select possible Hot DOGs in the Herschel Extragalactic Legacy Survey (HELP) covering ~1300 deg2 area on the Sky. In the next step, a careful analysis of the IR images can help to clean the sample to prepare it for the final study of those extreme sources at different redshift ranges.
    • Funding: NCBJ Fellowship
  11. Novel Research with Short-lived Atomic Nuclei
    • Supervisor: prof. dr hab. Zygmunt Patyk
    • Auxiliary supervisor: dr Volha Charviakova
    • Description: A successful candidate could perform unique research with short-lived nuclei to contribute to a better understanding of the strong and weak interaction and the origin of the chemical elements in the Universe. The discovery of new isotopes and the measurements of their properties will be a central effort. The experiments will be mainly performed at FAIR-GSI in Darmstadt, Germany, where Poland is a member state since the foundation.
    • Funding: NCBJ Fellowship
  12. Machine learning techniques for present day and future big cosmological surveys
    • Supervisor: dr hab. Agnieszka Pollo
    • Description: Machine learning techniques are now becoming more and more popular in astronomy, being applied to various tasks, from classification or clustering of data to regression-based parameter reconstruction or deep learning based image analyses. With increasingly rising sizes of sky surveys, application of automated techniques is no more a matter of choice but necessity. The successful candidate will develop and apply machine learning methods for reconstruction of galaxy properties and cosmological studies from present-day and future big sky surveys, with the aim to prepare a methodology for the coming data from big sky surveys, including the Large Synoptic Survey Telescope.
    • Funding: NCBJ Fellowship
  13. Data analysis for the new ultra-high energy cosmic ray observatories
    • Supervisor: prof. dr hab. Maria Szeptycka
    • Auxiliary supervisor: Dr Kenji Shinozaki
    • Description: Ultra-high energy cosmic rays, UHECRs, having 10<sup>20</sup> eV energies are the most energetic messengers ever observed in the history of astroparticle physics. Where and how they are produced have remained unknown since their discovery at Volcano Ranch in the 1960s. Due to their extremely low fluxes, these rare cosmic rays are only observable by detecting the subsequent process air shower phenomenon that is initiated by the UHECRs incident on the atmosphere. Key parameters of UHECRs such energies and arrival direction are indirectly determined by analysing this phenomenon. The successful candidate will collaborate in the JEM-EUSO programme. It aims at realising the future experiments in the satellite orbits to more efficiently observe UHECRs. For the future experiments in space, we will face distinctively different observation conditions from the ground-based observatories. The topic of this work will be solving a specific problem. For example, the intrinsic brightness of the atmosphere, the clouds, and human activities act as variable background noise. Characterisation of such noises and implementation into simulations are a mandatory requirement for the data analysis of the future experiment. The programme has conducted a few pathfinder experiments to acquire the data on the ground, on the balloons, and recently on the International Space Station and upgraded pathfinders are also planned. Together with simulation studies, this work also includes the analysis for the science data from the pathfinders with possible use of the data obtained by the other UHECR experiments.
    • Funding: NCBJ Fellowship
  14. Study of Vector Boson Scattering in the same-sign WW process at the CMS experiment
    • Supervisor: dr hab. Michał Szleper
    • Description: Vector Boson Scattering (VBS) processes belong to the most important tests of the Standard Model of particle physics.  They probe Higgs couplings to vector bosons W and Z, as well as triple and quartic couplings between bosons themselves.  In addition, scattering of longitudinally polarized vector bosons provides a direct glimpse of the mechanism of electroweak symmetry breaking.  In recent years the CMS and ATLAS experiments at CERN have observed for the first time the VBS processes at a level roughly consistent with Standard Model expectations, but more data is crucial in order to place better limits on Beyond Standard Model physics.  The successful applicant will participate in the analysis of the same-sign WW scattering channel in the leptonic W decay mode from CMS data collected during LHC Run 3.  He/she is expected to fully implement and develop the “clipping” technique to derive limits interpretable in the language of Effective Field Theories and to develop techniques to tag W/Z polarizations.  The project will also involve technical work on the CMS muon trigger system as part of the Warsaw CMS group activities.
    • Funding: NCBJ Fellowship
  15. 3D structure of proton in Quantum Chromodynamics
    • Supervisor: dr hab. Jakub Wagner
    • Description: Despite the great success in describing strong interactions within the framework of quantum chromodynamics, it is still not clear how quarks and gluons are bound inside the hadronic states, even in the simplest case of proton and neutron.During the past few decades the main effort to solve this problem mostly focused on the inclusive scattering, where properties of only some of the final state particles are measured. Lately, experiments with exclusive scattering, where all of the final state particles are identified, have attracted a lot of attention. Description of exclusive processes in terms of Generalized Parton Distribution allows in particular for the hadron tomography, i.e. the three-dimensional imaging of their structure. Nowadays, after exploratory experiments and almost 20 years of theoretical effort, measurements of exclusive processes are among the main goals of new generation experiments carried out at JLab (Hall-A, CLAS), CERN (COMPASS) and BNL (STAR, new Electron Ion Collider). A PhD student involved in this project will work on the theoretical description of exclusive processes, and on the extraction of properties of hadrons from published experimental data. Successful candidate will collaborate with an international team of physicists from Poland, France (IPNO, CEA Saclay, Ecole Polytechnique) and USA (JLAB, BNL). An experience with quantum field theory and basic programming skills will be an advantage.
    • Funding: NCBJ Fellowship
  16. Search for hadron exotic states at LHCb experiment at CERN
    • Supervisor: prof. dr hab. Wojciech Wiślicki
    • Auxiliary supervisor: dr Dmytro Melnychuk
    • Description: From the very beginning of the research in hadron physics the attention was focused on hadrons with properties that look unusual in contrast to the rest of the spectrum. Such hadrons are called exotic, however the concept of exotic is changing with time. Nowadays, to exotic hadrons the states different from conventional meson and baryons are assigned, such as tetraquarks and pentaquarks. In recent years more than twenty states with charm and beauty quarks not fitting into conventional description has been found and labeled as X, Y, Z, P. Among them there are several candidates for tetraquark and pentaquark states. LHCb experiment at CERN contributed significantly to observation and interpretation of these states and the search is ongoing with already collected data and with data which collection is going to resume from 2021 with much higher intensity and better accuracy. The PhD project concerns the search for new and interpretation of the nature of already observed exotic hadrons.
    • Funding: NCBJ Fellowship
  17. A roadmap for a CP violation signal in hyperon decays
    • Supervisor: dr hab. Andrzej Kupść
    • Description:  Violation of the charge parity (CP) symmetry is closely related to the baryon-antibaryon asymmetry puzzle and  may be harbinger of the physics beyond the standard model (SM). The Standard Model (SM) of particle physics predicts a tiny amount of CP violation exists but it is not sufficient to explain the overwhelming excess of the matter in the universe. The crucial property of baryons is their fractional spin, a quantum property which allows the ground state baryons to have two polarization states. Here, we plan to use a novel method to study CP symmetry for baryons containing strange quark, where the violation was never observed. The method uses baryon-antibaryon pairs produced in an electron-positron annihilations at the Beijing Electron Positron Collider (BEPCII). The spins of the baryons from such annihilations are correlated and polarized as recently observed for the first time.  Within the PhD project this novel method for the CP tests will be further developed to be used at BESIII and at the foreseen in the nearest future experimental facilities. The feasibility studies will use already collected BESIII data from J/psi resonance decays into baryon-antibaryon pair. The project includes participation in the BESIII experiment and a scholarship at Uppsala University.
    • Funding: NCN PRELUDIUM BIS