Pierre Auger Observatory

Azimuthal asymmetry in the risetime of the surface detector signals of the Pierre Auger Observatory

Billions of subatomic particles can be created in cosmic-ray induced air showers. They travel at nearly the speed of light through the atmosphere, and eventually through the surface detector water tanks of the Pierre Auger Observatory, deployed over 3000 km2 of the Argentine pampas. Because of their relativistic speed, when propagating in the water they generate a flash of so-called Cherenkov light, the same phenomenon that causes the bluish glow in a water pool of radioactive material. The light flash is faint and requires specialized electronic light sensors (photomultiplier tubes) that can detect the intensity of the light and its time structure. For example the "risetime" is measured: this is the time that it takes for the light generated to go from 10% to 50% of the total in the overall Cherenkov flash. This time is very short, of the order of a few hundred nanoseconds, thus the need for the specialized photomultiplier sensors.

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How airplanes were used for nanosecond-level time calibration of the Auger Engineering Radio Array

The Auger Engineering Radio Array (AERA) measures radio properties of cosmic-ray induced air showers within the Pierre Auger Observatory. The analysis of the radio data requires a very precise time-synchronisation between the individual radio detector stations. The GPS-clocks built into the AERA stations only provide a resolution of about 10 ns, whereas 1-2 ns is needed.

For this purpose, we conceived and installed a reference transmitter ("beacon") whose signals are recorded within the AERA data stream. Based upon these measurements the timing of each station is adjusted. But how can we independently check if this technique really achieves the precision we need?

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AugerPrime Press Release

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AugerPrime Symposium

Celebrating 15 years of achievements and signature ceremony of a new International Agreement for the next 10 years

The Pierre Auger Observatory is the world’s leading science project for the exploration of cosmic rays. More than 500 scientists from 16 countries have been working together since 1998 in the Province of Mendoza, Argentina, to elucidate the origin and properties of the most energetic particles in the Universe, coming to us from the far reaches of the cosmos. The Pierre Auger Observatory measures gigantic showers of relativistic particles that are the result of collisions between the very rare, highest-energy cosmic rays and atomic nuclei of the atmosphere. Properties of such air showers are used to infer the energy, direction, and mass of the cosmic particles.

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