Overview
My research focuses on computational methods in astroparticle physics and the detection of high-energy neutrinos and cosmic rays with the IceCube Neutrino Observatory at the South Pole and the Pierre Auger Observatory in Argentina. I am involved in the in-ice radio detection technique which is a promising method to open up a new window to the Universe at ultra-high energies that I recently described in a book chapter for the Encyclopedia of Cosmology. I am an active collaborator of the ARIANNA pathfinder experiment with detector stations on the Ross Ice Shelf and at the South Pole where I made major contributions to detector calibration and data analysis. I actively contribute to the Radio Observatory in Greenland (RNO-G, currently under construction) and member of its executive board. I am part of the leadership team for the future IceCube-Gen2 at the South Pole, the world’s largest facility for astroparticle physics with neutrinos. I am leading the simulation task for designing and optimizing the radio detector layout, and I am the designated lead for the commissioning of the radio array. I developed detector improvements that increase the neutrino detection rate at negligible additional costs and am involved in forecasting the science potential of IceCube-Gen2.
Deep learning techniques have huge potential to advance physics. I am pioneering the use of deep learning for event reconstruction of in-ice radio detector data and to enhance the trigger. I developed a new course on “Application Oriented Deep Learning in Physics” for Ph.D. and advanced undergraduate students that I teach at Uppsala University. I am a member of the MODE collaboration that brings together computer scientists and experimental physics to promote and facilitate end-to-end detector optimizations with deep learning and differential programming (see the white papers of the MODE collaboration). I co-organize the MODE workshop series (Valencia, September 2024). A PostDoc in my group leads the IceCube reconstruction working group.
I initiated and lead the development of the open-source codes NuRadioMC and NuRadioReco. NuRadioMC is the state-of-the-art simulation code for in-ice radio detectors. NuRadioReco is a modular reconstruction framework to facilitate the analysis of radio detector data. Both tools became the de-facto community standard for in-ice radio detectors and are used by all current and future experiments (ARA, ARIANNA, RNO-G, IceCube-Gen2). Both codes are actively developed with a large development team of more than 30 scientists that I coordinate in weekly meetings. An increasing number of studies built upon NuRadioMC/Reco (as of Aug. 2023: 42 journal publications and conference proceedings). To reach the next level of precision, my group studies how birefringence affects the propagation of radio signals in polar ice and I am involved in the CORSIKA8 project for a microscopic shower simulation in inhomogeneous media. My group has recently taken over the coordination of software development.
I developed several new analysis techniques and tested them with in-situ calibration data from test setups at the South Pole and the Ross Ice Shelf, Antarctica. This includes the D’n’R technique to determine the distance to a neutrino interaction and the forward folding technique to recover the signals at small signal-to-noise ratios. The latter is now being used to provide the most precise determination of the direction and polarization of cosmic rays and neutrinos. Using the D’n’R technique, my group developed an in-situ calibration system for the ice properties to reduce systematic uncertainties of the neutrino direction and energy.
From 2012 – 2017, I was a member of the Pierre Auger Collaboration, which operates the world’s largest observatory for cosmic rays in Argentina. I made major contributions that allowed the radio technique to mature into a competitive alternative to existing approaches. I contributed to the deployment and calibration of the radio array and presented results on behalf of the Pierre Auger Collaboration at four international conferences. I measured the radiation energy in the radio signal of extensive air showers, where I developed the reconstruction technique, conducted the measurement, and developed the phenomenology to use it as a universal estimator of cosmic-ray energy. This a cornerstone of the Auger Prime upgrade of the Pierre Auger Observatory to measure the chemical composition of cosmic rays.