At large zenith angles the slant atmospheric depth to the ground level
is sufficient to absorb the early part of the shower that follows from
the standard cascading interactions, both of electromagnetic and hadronic type.
Nucleon induced showers are initiated at the top of the atmosphere.
For very inclined showe only muons
in showers survive. The fronts of deeply penetrating muon
showers have only a small longitudinal extension, which leads to short
detector signals. “Old” showers generate short traces of very similar shapes
at all core distances.
Inclined showers mainly composed of muons, allow a direct measurement of
the muon content at ground level and as a consequence, they
can be used to study mass composition and to test high-energy hadronic
interaction models. The Pierre Auger Observatory is particularly well suited
for the detection of inclined showers because the water Cherenkov tanks used
for the surface detector act like volume detectors.
The standard data acquisition system quantizing the analog signals in ADCs,
according to the ``Golden rules'', is equipped with the anti-aliasing filter
with the cut-off Nyquist frequency. However, very short pulses, typical for
very inclined showers, are significantly suppressed by the anti-aliasing
filter and their amplitude may be not enough to generate the 3-fold
The paper presents the theoretical analyses of the anti-aliasing Auger
filter response as well analyses of measured Auger data. We conclude that
for a detection of non-standard rare events maybe it is worth considering
non-standard approach and resign with the standard Golden rules.
|Institute||University of Lodz|