Comparison of UHE Composition Measurements by Fly's Eye, HiRes-prototype/MIA and Stereo HiRes Experiments

TL;DR

This paper compares ultra-high-energy cosmic ray composition measurements from three air-fluorescence experiments, finding that systematic shifts reconcile their results and allow combined analysis across a broad energy range.

Contribution

It demonstrates that applying a systematic shift aligns data from different experiments, enabling a unified interpretation of UHE cosmic ray composition.

Findings

Systematic shift of 13 g/cm^3 aligns datasets

Combined dataset covers energies from 10^17 to 10^20 eV

Results suggest consistent composition measurements across experiments

Abstract

We compare the elongation rate and Xmax distributions for three air-fluorescence experiments: Stereo Fly's Eye, HiRes/MIA, and HiRes. A shift of 13 gm/cm^3 of the stereo Fly's Eye data, well within the quoted systematic errors, brings the elongation rates and the Xmax distributions of all three experiments into reasonable agreement. We explore the implications of this combined dataset ranging from 10^17 eV to near 10^20 eV.