Atmospheric Calorimetry above 10$^{19}$ eV: Shooting Lasers at the Pierre Auger Cosmic-Ray Observatory

TL;DR

This paper discusses the use of calibrated pulsed UV lasers as test-beams to simulate ultra-high energy cosmic rays for atmospheric calorimetry at the Pierre Auger Observatory, aiding energy response understanding.

Contribution

It introduces laser-based test-beams to calibrate and understand the energy response of the observatory at extreme cosmic-ray energies.

Findings

Laser test-beams effectively simulate cosmic-ray air-shower signatures.

Calibration improves energy measurement accuracy for ultra-high energy cosmic rays.

Results support the observatory's capability to study cosmic-ray propagation and origins.

Abstract

The Pierre Auger Cosmic-Ray Observatory uses the earth's atmosphere as a calorimeter to measure extensive air-showers created by particles of astrophysical origin. Some of these particles carry joules of energy. At these extreme energies, test beams are not available in the conventional sense. Yet understanding the energy response of the observatory is important. For example, the propagation distance of the highest energy cosmic-rays through the cosmic microwave background radiation (CMBR) is predicted to be strong function of energy. This paper will discuss recently reported results from the observatory and the use of calibrated pulsed UV laser "test-beams" that simulate the optical signatures of ultra-high energy cosmic rays. The status of the much larger 200,000 km$^3$ companion detector planned for the northern hemisphere will also be outlined.