Precise Measurement of the Absolute Yield of Fluorescence Photons in Atmospheric Gases

Understand

We have performed a measurement of the absolute yield of fluorescence photons at the Fermilab Test Beam.

• A systematic uncertainty at 5% level was achieved by the use of Cherenkov radiation as a reference calibration light source.
• A cross-check was performed by an independent calibration using a laser light source.
• A significant improvement on the energy scale uncertainty of Ultra-High Energy Cosmic Rays is expected.