PhD ceremony Mr. E.D. Fraenkel: From radio pulse to elusive particle

PhD ceremony: Mr. E.D. Fraenkel

Dissertation: From radio pulse to elusive particle

Promotor(s): prof. A.M. van den Berg, prof. O. Scholten

Faculty: Mathematics and Natural Sciences

Cosmic rays are mysterious and very energetic particles from space. There is much to be learnt about the origin and nature of these elusive particles. When a cosmic ray hits the earth's atmosphere this creates a cascade of millions to billions of secondary particles: an air shower. This air shower travels towards the earth's surface and is detected the Pierre Auger Observatory in Argentina. This observatory consists of a 1600 particle detectors which are spread out over an area as large as Washington.

Recently, the Pierre Auger Collaboration has developed an additional technique to measure cosmic rays by using radio antennas. The antennas measure radio pulses which are created by these air showers.

The work focuses on the detection techniques and tackles some technical problems involving the detection of these pulses. Detection is difficult because the pulses are very short-lived and barely register above the galactic background noise. The situation is exacerbated by the effects of human made radio interference. A novel method based on linear prediction is developed to filter out (some of) the human made background noise. It turns out that the method based on linear prediction is especially useful for applications in real-time data taking in the embedded software of the radio detectors.

Additionally, two physical processes involved in the creation of these pulses are identified and disentangled by comparing the first measurements with simulations from six different software packages. This brings us closer to a deeper understanding of the physics of radio emissions from cosmic-ray-induced air-showers.