Karlsruhe School of Elementary Particle and Astroparticle Physics: Science and Technology (KSETA)

Steffen Hahn

PhD (DDAp, Helmholtz International Research School) student at KIT (IKP, Pierre Auger)


Institute IKP
Group Pierre Auger
Supervisors Prof. Dr. Ralph Engel (KIT), Dr. Markus Roth (KIT), Prof. Dr. Brian Wundheiler (ITEDA)
Location Campus North, Building: 425, Room: 102
Contact steffen.hahn(#)kit.edu


PhD topic

Title (preliminary): Muon signal estimation and determination of primary particle mass of cosmic rays from data obtained by the upgraded Pierre Auger Observatory using deep neural networks

In recent years, the application of neural networks has made it possible to solve many interesting and hard problems in various fields of research. One of the most prominent examples showing this was the decisive victory of AlphaGo against the human world elite in the ancient game of Go. Especially, since at this time, there was no game engine near the level of the Go grandmasters. Being used as analysis tool for the board positions exhibits the capability of neural networks in the area of pattern recognition at a better-than-human level. Furthermore, not only in classification problems, but also in regression problems they show promising results if many network layers are used (deep). Therefore, it is reasonable to use this powerful tool in physics. For the last couple of years people tried to find a robust way of extracting the signal generated by muons in the suface detectors of the Pierre Auger observatory. Attaining a better knowledge of this quantity could simplify the inference of the primary particle mass of the corresponding cosmic shower. This in turn could potentially enable us to understand the muon excess found in the data of Pierre Auger. The design, application, and inference out of a deep learning approach is the main topic of this thesis.

Research interests (general)

  • astropaticle physics
  • machine learning
  • cosmology


Title (year) Supervisors
Modifizierte Quasiteilchen-Phasenrückgewinnung für verrauschte (in vivo) Datensätze und tomografische Rekonstruktionen (2015) Prof. Dr. Tilo Baumbach, PD Dr. Ralf Hofmann
The postulate that the CMB is a thermal SU(2) Yang-Mills plasma and implications thereof for the cosmological model (2018) Prof. Dr. Thomas Schwetz-Mangold, PD Dr. Ralf Hofmann

Participation and teaching

Experiments, Conferences, ...

Event Date
Start in die Lehre 10/2012
Experiment LS/2350, ID 19, European Synchrotron Radiation Facility (ESRF) 11/2014
Inhouse beamtime, ID 19, ESRF 04/2015
Experiment LS/2395, ID 19, ESRF 06/2015
Advanced Summer School on Reconstruction Methods in Tomography (MART-3D) 09/2016
5th Winter Workshop on Non-Perturbative Quantum Field Theory (WWNPQFT) 03/2017
Experiment MA-3473, ID 19, ESRF 07/2017

Teaching and assistance

Name Type Time
Höhere Mathematik I - Biologie und Chemie Tutorial WS 12/13
Stützkurs Felder Tutorial SS 13
Praktikum klassische Physik I Tutorial WS 13/14
Praktikum klassische Physik II Tutorial SS 14
Praktikum klassische Physik I Tutorial WS 14/15
Moderne Experimentalphysik 1 Tutorial SS 15
Wissenschaftliche Hilfskraft: IPS Assistance 12/16--03/18


Hofmann, R., Schober, A., Hahn, S., Moosmann, J., Kashef, J., Hertel, M., Weinhardt, V., Hänschke, D., Helfen, L., Salazar, I. A. S., et al. (2016). Gauging low-dose x-ray phase-contrast imaging at a single and large propagation distance. Optics express, 24(4):4331--4348.

Hahn, S., Müller, Y., Hofmann, R., Moosmann, J., Öktem, O., Helfen, L., Guigay, J.-P., van de Kamp, T., and Baumbach, T. (2016). Spectral transfer from phase to intensity in fresnel diffraction. Physical Review A, 93(5):053834.

Cecilia, A., Baecker, A., Hamann, E., Rack, A., van de Kamp, T., Gruhl, F., Hofmann, R., Moosmann, J., Hahn, S., Kashef, J., et al. (2017). Optimizing structural and mechanical properties of cryogel scaffolds for use in prostate cancer cell culturing. Materials Science and Engineering: C, 71:465--472.

Trost, F., Hahn, S., Müller, Y., Gasilov, S., Hofmann, R., and Baumbach, T. (2017). Fresnel diffractograms from pure-phase wave fields under perfect spatio-temporal coherence: Non-linear/non-local aspects and far-field behavior. Scientific reports, 7(1):17706.

Hahn, S. and Hofmann, R. (2017b). SU(2)cmb at high redshifts and the value of H0. Monthly Notices of the Royal Astronomical Society, 469(1):1233--1245.

Hahn, S. and Hofmann, R. (2017a). Cosmic microwave background as a thermal gas of SU(2) photons: Implications for the high-cosmological model and the value of H0. Advances in High Energy Physics, 2017.

Hahn, S. and Hofmann, R. (2018). Exact determination of asymptotic cmb temperature-redshift relation. Modern Physics Letters A, 33(05):1850029.

Hahn, S., Hofmann, R., and Kramer, D. (2018). Su (2) cmb and the cosmological model: angular power spectra. Monthly Notices of the Royal Astronomical Society, 482(4):4290--4302.

This part was generated by bibtex2html 1.98.