Thesis Projects
In all the research areas we can offer Master's and Bachelor's thesis topics. Please get in touch with Prof. Issever(isseverc@hu-berlin.de). Here are some examples of available topics:
Master Thesis Topics:
- Phenomenology studies for diHiggs to 4b sensitivity studies:
In the context of the ERC HiggsSelfCoupling project, we have this phenomenology study that aims to improve the sensitivity of our searches for diHiggs to 4b events and also the measurement of the Higgs self-coupling parameters. In this study, you would work with neural network algorithms and simulated collision events.
- Development of novel flavour tagging techniques using neural network algorithms:
This project would involve working with Prof. Todd Huffman at Oxford University and Dr Spyros Argyropoulos at Freiburg University on novel flavour tagging techniques by modifying or developing a neural network that is used to “tag” high energy jets generated at the Large Hadron Collider in the ATLAS experiment at CERN.
Starting from a framework that contains the information of hit multiplicities in jets, the student would study the impact of additional hit variables (e.g. the probability of the hit to originate from more than one charged particle) on the performance of the ATLAS Deep Learning algorithms for b-tagging. The existing framework needs to be retrained with more simulations, but in addition, we would like the student to extend these “hit-based” additions to the Neural Network to include clusters that appear in new regions of the detector that have not been previously considered, specifically the outer SCT strip tracker and also the pixel disk detectors. We would also like to explore the possibility of using a Graph Neural Network where the pixel position, but also the energy and angle of the highest energy track in the jet provide a kind of “picture” that GNN systems seem particularly suited to recognize as a pattern. This last project extension depends upon whether the appropriate framework can be established and how quickly the first parts of the project progress.
Since this project will be in collaboration with colleagues in the UK the student should be fluent in English. Experience in programming is also desirable.
- GEANT4 + ALLPIX2 simulations for novel digital calorimetry:
In order to define the performance requirements of future sensor designs for digital calorimetry we need to have a robust simulation framework of both single DECAL/ MALTA sensors but also of the MALTA telescope at the SPS CERN facility. The simulation software will meaningfully contribute to the DRD6 collaboration in terms of the development of new tools. The simulation results will be validated against test beam data in order to yield a complete experimental study.
- Construction of a high energy cosmic ray telescope with MALTA2 planes:
High energy beams are the most convenient testing venues for particle detectors. Often times they are overbooked or prohibitively expensive. One can however use the natural abundance of cosmic muons that penetrate through Earth's atmosphere as a primary particle source. As such, a miniaturized high energy particle telescope can be designed as a table-top laboratory experiment. The thesis work will require the development of a compact particle telescope that allows for the testing of different sensors.
- GEANT4 simulations of Compton Cameras for medical imaging applications:
This task is related to the development of a compact and light-weight diagnostic tool for medical imaging applications. Compton cameras provide a very good energy and position resolution for such applications. We want to optimize our sensor design with the help of GEANT4 simulations.
This task requires good knowledge of C++ object oriented programming.
- Measurement of pion exchange processes in proton-proton and proton-Oxygen collisions at the LHC:
Until now, the accuracy of the state-of-the-art modelling of strong interaction processes at high energies and low momentum transfer is very limited. During their measurements in run 2, the LHCf collaboration found indications of proton-proton scattering through the exchange of a pion, leading to the transformation of one of the protons into a neutron and the other proton to dissociate into hadrons. This process so far has been unaccounted for in the currently available event generators. In run 3, LHCf was able to gather more than twice the data than it did in run 2. With this data and together with information on activity in the central pseudorapidity range from the ATLAS detector, the presence of a pion exchange process in proton-proton could be confirmed. Furthermore, the possibility of measuring scattering processes through pion exchange in the upcoming proton-Oxygen collision run at the LHC could be investigated.
Bachelor Thesis Topics
- Preparatory studies on proton-oxygen collisions at the LHC:
One of the most important sources of uncertainties in studying cosmic rays with Cherenkov telescopes is the modelling of hadronic interactions of an incoming cosmic particle and an atomic nucleus in Earth's atmosphere. In the upcoming Run 3 of the LHC, a unique opportunity presents itself to explore exactly those interactions under laboratory conditions by studying collisions of protons and Oxygen nuclei with the help of the ATLAS detector and other detectors in the forward region of ATLAS. The goal of this Bachelor project will be to study adequate observables with which individual hadronic processes can be separated and isolated from background processes. This should enable us to measure the cross sections of those processes and the energy spectra of the created particles, as soon as the p-O collision data have been taken at the end of Run 3. Moreover, the detector positions in the forward region and the beam optics of the LHC should be optimized for such a measurement.
- Measurement of Bremsstrahlung in highly energetic proton-proton collisions at the LHC:
Bremsstrahlung, i.e. the spontaneous emission of a photon by one (or both) of the beam protons either before of after the collision of two protons has never been measured so far at energies as high as can be reached at the LHC. The process would leave a very clear signature of two forward protons and one (or two) forward photons (i.e. at high pseudorapidities) and no activity in the central region (at low pseudorapidities). Recently, data was taken during a special run at the LHC, in which simultaneous information could be gathered from forward neutral calorimeters (LHCf and ATLAS-ZDC), forward proton trackers (AFP) as well as the ATLAS detector. A feasibility study could be conducted to explore the potential of this data to measure Bremsstrahlung for the first time at such high energies. For this, the acceptances of the individual detectors for this process have to be determined as well as their combined acceptance. Furthermore, potential background sources have to be studied.
- Literature review on the feasibility of quantum dots as an alternative for calorimetry:
An emerging technology in the world of instrumentation for particle physics are quantum dots. As the requirements for future collider experiments become more stringent, a push towards novel technologies/ materials is important. This project includes the familiarization with the concept and principles of quantum dot materials. Furthermore, an extensive literature survey will be performed in order to generate a report on the feasibility of quantum dots for calorimetry applications.
- Development of a cooling system for a laser set-up:
Laser testing of silicon Monolithic Active Pixel Sensors (MAPS) is a light-weight and cheap alternative to test beam measurements. The testing of irradiated sensors with a laser set-up will provide us with important device characterization. The operation of irradiated sensors requires a low temperature (-20C) and a low humidity (<5%) in order to maintain a low dew point. The thesis work requires the development of a cooling and humidity control system for the enclosed laser box.
This task requires familiarization with Computer Aided Design (CAD) tools.
- Study of the limitations of the MALTA2 tracking sensor for calorimetry applications:
Silicon sensor redesign is often a costly and time intensive procedure. We would like to understand the limitations of a sensor designed for efficient high energy particle tracking when employed in a digital calorimetry applications. The thesis work will involve several experiments with a laser set-up with the aim of characterizing the particle counting saturation.
- Scintillator and Silicon PhotoMultiplier characterization:
This task involves the testing of several scintillation crystals together with Hamamatsu Silicon PhotoMultipliers (SiPMs). The energy resolution of different crystals will be measured with the help of calibration radioactive sources in order to validate supplier requirements. Additional experiments with LEDs and lasers will be employed on several SiPMS to measure inter-channel variances.
This task requires programming skills for data analysis (either in python or ROOT).
PhD Thesis Topics
Current and Former Thesis Projects
- Lucian Fasselt M.Sc.
Characterization of the DECAL sensor - a CMOS MAPS prototype for digital electromagnetic calorimetry and tracking (1/2023)
- Anne-Kathrin Westen M.Sc.
Investigation of new hit-based quantities in high energy trackless b-quark tagging with a Neural Network in the ATLAS experiment (10/2022)
- Tim Schwägerl M.Sc.
A pattern recognition algorithm for Noisy Intermediate-Scale Quantum devices (5/2022)
- Marie Luise Sturm B.Sc.
Dependence of the sensor characteristics of the DECAL Chip on the bias voltage (3/2023)