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

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

Parsimonious estimation of signal detection models from confidence ratings

Signal detection theory (SDT) is used to quantify people's ability and bias in discriminating stimuli. The ability to detect a stimulus is often measured through confidence ratings. In SDT models, the use of confidence ratings necessitates the estimation of confidence category thresholds, a requirement that can easily result in models that are overly complex. As a parsimonious alternative, we propose a threshold SDT model that estimates these category thresholds using only two parameters. We fit the model to data from Pratte et al. (Journal of Experimental Psychology: Learning, Memory, and Cognition, 36, 224-232 2010) and illustrate its benefits over previous threshold SDT models

Is conscious processing required for long-term memory?

Models of memory (including those of the SAM-REM variety) are generally based on the assumption that storage of information in long-term memory is a function of the amount of elaborative processing given to the processed information. Here we explore the limits of such an assumption by examining the long-term effects of information that has only been processed at a subliminal level. We conclude that even subliminally presented information is stored to some extent and will lead to small but consistent effects in indirect memory tests but not on direct memory tests. To have an effect on a direct memory test, the information has to be clearly seen (as in the RSVP experiments discussed in this chapter) although here again, attentive processing does not appear to be required