Absolute fluorescence yield is a crucial value used for energy reconstruction by fluorescence detectors of cosmic rays. This paper is presenting a result of ten years of comprehensive studies of the air fluorescence process by the AirFly group. The total uncertainty of the absolute fluorescence yield, which propagates into the uncertainty of the energy reconstruction of high-energy-cosmic-ray detectors, has been lowered from 15% to 4%.
The AIRFLY experimental setup: (1) stainless steel chamber; (2) integrating sphere; (3) top port; (4) plug of exit port; (5) 337 nm interference filter; (6) acceptance apertures; (7) PMT; (8) extension for beam particle path; (9) scintillator disk counter; (10) Cherenkov counter, with acrylic rod and photomultiplier; and (11) veto counters.
Our group has been part of the AirFly collaboration since the beginning, contributing to the simulations, hardware, data taking as well as analysis. The major contribution to this particular paper was the design and preparation of the interaction chamber and of the experimental setup, total Monte Carlo simulation of the experiment, participation in data taking and analysis.