Antennas for the detection of radio emission pulses from cosmic-ray induced air showers at the Pierre Auger Observatory

Abstract

The Pierre Auger Observatory is exploring the potential of the radio detection technique to study extensive air showers induced by ultra-high energy cosmic rays. The Auger Engineering Radio Array (AERA) addresses both technological and scientific aspects of the radio technique. A first phase of AERA has been operating since September 2010 with detector stations observing radio signals at frequencies between 30 and 80 MHz. In this paper we present comparative studies to identify and optimize the antenna design for the final configuration of AERA consisting of 160 individual radio detector stations. The transient nature of the air shower signal requires a detailed description of the antenna sensor. As the ultra-wideband reception of pulses is not widely discussed in antenna literature, we review the relevant antenna characteristics and enhance theoretical considerations towards the impulse response of antennas including polarization effects and multiple signal reflections. On the basis of the vector effective length we study the transient response characteristics of three candidate antennas in the time domain. Observing the variation of the continuous galactic background intensity we rank the antennas with respect to the noise level added to the galactic signal.

The Energy Content of Extensive Air Showers in the Radio Frequency Range of 30-80 MHz

“…In this phase, AERA consisted of 24 antenna stations with a spacing of 144 m. The stations are equipped with logarithmic-periodic dipole antennas and measure over a frequency range of 30 to 80 MHz [21]. We use only events that have been measured by the radio and surface detectors in coincidence.…”

“…We correct for the influence of the analog signal chain using the absolute calibration of the AERA station and reconstruct a three-dimensional electric field by using the direction of the shower and applying the simulated antenna response [21]. An example of a reconstructed electric field trace E(t) is shown in Fig.…”

“…The average fit uncertainty of S radio is 46% and reduces to 24% in case of events with five or more stations with signal. The absolute scale uncertainty of the energy estimator is dominated by the absolute scale uncertainty of the antenna response pattern (25%) [21] and the analog signal chain (12%) and amounts to 28%. All uncertainties are added in quadrature.…”

Laboratory tests of two-dimensional wavelet trigger in radio detection of cosmic rays

“…The frequency window for the maximal antenna efficiency is ∼30 -80 MHz [11]. This range is additionally filtered by a band-pass filter.…”

Radio detection of Cosmic Rays with LOFAR

“…An inspiring article, published in 2003 [3] accompanied the renaissance of radio detection of extensive air showers with the ultimate goal to measure the properties of cosmic rays with this technique and the pioneer experiments LOPES [4] and CODALEMA [5] have been initiated. The big success of these pathfinders stimulated further investigations of the radio emission of air showers on larger scales, with installations such as Tunka-Rex [6], AERA at the Pierre Auger Observatory [7,8], and the LOFAR radio telescope. Significant progress has been achieved in the last decade [9] and we now understand the emission processes of the radio waves in the atmosphere.…”