Martin Schimassek

Search for transient sources of low-energy cosmic rays with the Pierre Auger Observatory

The Pierre Auger Observatory was built to measure cosmic rays with the highest energies and has 1660 surface detectors deployed over an area of 3000km2, overlooked by four fluorescence detector sites. Periodically also non-event data are recorded for each of the array stations, which are mainly used for hardware calibration and performance monitoring, but they indirectly carry also information about particles with energies in the MeV to GeV range and can therefore be used for physics analyses aimed at the low-energy part of the spectrum. The sensitivity of such analyses to small changes in rates is due to the large statistics collected by the stations, each having an area of about 10m2. With these data we can observe changes in solar activity and Forbush decreases in the rate of low-energy cosmic rays on the typical time scales of hours to days. On the time scales of seconds we were searching for signals of very high-energy emissions originating from gamma-ray bursts.