Ultra-high-energy cosmic rays are the most energetic particles known in nature, but scientists still do not know exactly where they come from or what they are made of. When these particles enter Earth’s atmosphere, they produce vast cascades of secondary particles, accompanied by brief radio signals that can be detected by antennas on the ground.
This thesis investigates how these radio signals can be combined to study cosmic rays more precisely. I developed and tested methods to synchronise antennas with extremely high timing accuracy and applied radio interferometry, a technique that combines signals from multiple antennas to produce a clearer reconstruction.
The results show that radio interferometry can improve the reconstruction of very inclined particle showers at the upgraded Pierre Auger Observatory in Argentina. By providing more detailed information about how these showers develop in the atmosphere, this work will help scientists determine the composition of ultra-high-energy cosmic rays and ultimately better understand the nature and origins of the Universe’s most energetic particles.
Anthony Bwembya was born in Lusaka, Zambia, where an early fascination with energetic particles and scientific instruments set the course for his career. He studied Physics at the University of Zambia, then earned a master's degree in Nuclear Physics and Technology at the National Research Nuclear University MEPhI in Moscow.In 2021, he began doctoral research at Radboud University as part of the international Pierre Auger Collaboration, focusing on estimating the mass composition of cosmic rays from their radio signals. His work spanned precision timing, detector calibration and monitoring, radio signal processing, and field measurements at the Pierre Auger Observatory in Argentina. Along the way, he developed methods enabling radio antennas to reconstruct cosmic-ray particle showers, including the first successful interferometric reconstruction of a very inclined air shower using the observatory's upgraded radio detector.