Study of the High Energy Cosmic Rays with the Pierre Auger Observatory

The Pierre Auger Southern Observatory, a hybrid detector for the study of ultrahigh energy cosmic rays (UHECRs), has now been operating for more than five years and has reached completion. This contribution describes the present status and performance of the Observatory, showing the advantages provided by the combined use of two different detection techniques. Selected results are presented with the emphasis given to the measurement of energy spectrum, arrival directions at the highest energies and search for photons as primary particles

SD electronics: simulations on the dynamic range

The surface detector electronics of the Pierre Auger Observatory is characterized by a large dynamic range due to the variation of the signal intensity of the Cherenkov tanks as a function of the distance from the core. In this paper, we present results of simulations and discuss the impact of the dynamic range on the shower reconstruction

The Use of the Signal at an Optimal Distance from the Shower Core as a Surrogate for Shower Size

When analysing data from air-shower arrays, it has become common practice to use the signal at a considerable distance from the shower axis (_opt) as a surrogate for the size of the shower. This signal, (_opt), can then be related to the primary energy in a variety of ways. After a brief review of the reasons behind the introduction of opt laid out in a seminal paper by Hillas in 1969, it will be shown that _opt, is a more effective tool when detectors are laid out on a triangular grid than when detectors are deployed on a square grid. This result may have implications for explaining the differences between the flux observed by the Auger and Telescope collaborations above 10 EeV and should be kept in mind when designing new shower arrays

Design of the photomultiplier bases for the surface detectors of the Pierre Auger Observatory

The design of the photomultiplier bases for the surface detectors of the Pierre Auger Observatory is presented. The bleeder is purely resistive. The base comprises two outputs: one from the anode and another one from the last dynode followed by an amplifier. The charge ratio between the anode and the amplified dynode is around 30. The design ensures a low consumption (less than 100 mu A at 2 kV), a stability of the gain and of the base line during the whole period of measurement (20 mu s per event) and for the whole dynamic range (max. 1 to 3x10^4 in amplitude). First measurement with a prototype base on the Hamamatsu R5912 photomultiplier tube are presented