Nikhef researcher Harm Schoorlemmer receives ERC Consolidator grant

4 December 2024

The European Research Council (ERC) has awarded its 2024 Consolidator Grants to 328 researchers across Europe. These grants, totalling €678 million, aim to support outstanding scientists and scholars as they establish their independent research teams and develop their most promising scientific ideas.

Nikhef researcher Harm Schoorlemmer (cosmic rays/Auger group) has received one of the grants (3 million euros) for his proposal called ‘Air shower interferometry to advance astroparticle physics’. Schoorlemmer: “I am very grateful to the ERC for awarding me the grant. The core of the research is to improve observations of particle avalanches caused by cosmic rays. We do this by applying interferometric techniques to the radio emission emitted by these avalanches. To make a broad impact in astroparticle physics, we are going to apply this technique at the ‘Pierre Auger Observatory’ and the ‘Southern Wide-field Gamma-ray Observatory’. I look forward to what we will learn about the most energetic particles in the universe.”

The ERC, set up by the European Union in 2007, is the premier European funding organisation for excellent frontier research. It funds creative researchers of any nationality and age, to run projects based across Europe. The ERC offers four core grant schemes: Starting Grants, Consolidator Grants, Advanced Grants and Synergy Grants.

Source: ERC

The proposal that Schoorlemmer that earned him the grant:
The universe hosts a population of subatomic particles with astonishingly high kinetic energies, so-called cosmic rays. Where and how they obtain this energy is unknown. These particles initiate cascades of particles in the atmosphere called air showers. The particle interactions within air showers are not fully understood and probe a regime not easily accessible by particle accelerator experiments.
I developed a new technique that applies interferometry on the radio emission from air showers. It improves the reconstruction accuracy of air shower properties and hence allows for better determination of the features of cosmic particles. The largest facility for ultra-high-energy cosmic ray detection, the Pierre Auger Observatory, is upgrading its infrastructure to include 1660 radio antennas. This CoG facilitates the interferometric technique for the upgrade by deploying an accurate synchronisation system. The Southern Wide-view Gamma-ray Observatory is a next-generation facility, starting construction in 2026. This CoG augments it with 800 antennas to perform interferometry on air showers.
By improving the air shower reconstruction of these facilities, we aim to extend their capabilities to address major open questions in astroparticle physics. Specifically, the combination of particle detection and interferometry is used to reach these objectives:
       Determine which particles contribute to the cosmic-ray flux at the highest energies, by measuring air shower depth.
       Accurately measure the hadronic interactions in air showers, by simultaneously detailed observations of the muon and electromagnetic components of air showers. The same technique is applied over a wide cosmic-ray energy range. 
       Observe astrophysical photons with energies above 1015 eV, to identify the most extreme particle accelerators in our galaxy.
This CoG pioneers the interferometric air shower reconstruction on a large scale and will pave the way for its use in future projects.