Antenna devices and measurement of radio emission from cosmic ray induced air showers at the Pierre Auger Observatory

摘要

Radio detection of air showers originating from ultra-high energy cosmic rays is considered world wide as a candidate technique for the next generation of Earth bound cosmic ray observatories. In the research and development of this technique major challenges concern the antenna sensor, signal processing, triggering and data interpretation. In this thesis we present hardware and software developments, central simulations studies, theoretical calculations, calibrations and data analysis for the overall development of two engineering radio arrays at the Pierre Auger Observatory with special emphasis on the antenna sensor. The transient nature of the air shower signal requires a detailed description of the antenna to allow for a calibrated measurement of the incident signal. We identify the vector effective length as suitable quantity to perform the calculation of the antenna response to transient signals including multiple reflections, interference and polarization effects. We present our research and development including the calibration of the antenna which is used in the current setup of Auger Engineering Radio Array (AERA). Using air shower data from a pioneering radio detector installation we study the lateral fall-off of the radio signal with increasing distance to the air shower axis. Furthermore, we study the data that is recorded during the start up phase of AERA. We characterize major sources of transient signals in the vicinity of AERA in three-dimensional space. We introduce a method for the rejection of background signals which results in an efficient selection of air showers from the AERA data set. Finally, we evaluate candidate antennas for the next setup phase of AERA regarding their response characteristics to transient waveforms. Using comparative measurements of the variation of galactic radio signals performed at the Nançay Radio Observatory we discriminate the candidate antennas with respect to an optimal noise performance.