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
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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.
- Commissioning of a laser characterisation system and first studies:
In order to use the laser system, we first need to perform the commissioning: Study how to correctly focus the laser light to hit a specific detector element as well as correlate the time of the laser pulse with the readout of the sensors. After these two aspects have been accomplished the data of the laser light illumination can be used to study the sensor's characteristics.
This task fits best the duration of a master thesis but could be split into multiple tasks for a bachelor thesis.
- Develop simulations of the expected DECAL performance:
In order to understand how we can go from the characterization of single DECAL sensors to a full detector prototype, i.e. a sampling between multiple sensor and absorber layers, an optimization using simulation needs to be performed. This includes the development of the simulation software. Additionally, the simulation should be used to compare the performance between digital and analogue calorimeters.
This task cannot be performed in the time scale of a bachelor thesis. Here, the student would need to collaborate with our UK colleagues.
- 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
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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.
- Further studies on the electronic noise of the sensor:
Electronic noise is one of the crucial items to be understood for using DECAL as a calorimeter. We want to measure extremely soft particles as such particles are created in showers expected from collisions at a high-energy particle collider. In order to measure these soft particles, the electronic noise of the sensor needs to be small. The first studies on this had been performed by a former student, but this issue needs to be studied in greater depth.
- Studies of the temperature dependency of the sensor output:
In previous studies, we found that the sensor’s readout depends on its temperature. As the sensor is an electronic device, its readout creates heat, thus the understanding of the impact of the temperature on the readout is crucial to know. We have a thermal heat camera in our laboratory. This project includes developing a way to read out pictures of the thermal heat camera in a systematic way.
This task fits best the duration of a bachelor thesis. It might require some advanced programming skills to develop the read-out of the pictures of the thermal camera.
- Development of a graphic user interface for easing the operation of the DECAL sensor
This task is aimed at improving the outreach capabilities of the DECAL project. We believe outreach is a very important aspect of science. We perform regular outreach events at HU but also take on interns such as high school students who come to us to understand what researching entails. Currently, the testing of the DECAL sensor can be only performed with some expert knowledge such as a basic understanding in using command line tools and C++. In order to allow these high-school students to experience this type of research, we want to build a graphical user interface that is intuitive.
As this project is not research by itself, it is aimed towards students in the teaching track (Lehramtsstudierende). Please note that this task includes significant programming.
- 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.
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)