Comment on Japanese Detection of Air Fluorescence Light from a Cosmic Ray Shower in 1969

TL;DR

This paper reviews and confirms the 1969 claim of detecting a high-energy cosmic ray air shower via fluorescence light, highlighting its significance as the first such observation and its influence on future experiments.

Contribution

It re-evaluates a historic 1969 detection claim, affirming its validity and emphasizing its foundational role in cosmic ray research.

Findings

Likely observation of fluorescence light in 1969 confirming the first cosmic ray air shower detection.

The 1969 work influenced modern cosmic ray experiments like Pierre Auger Observatory.

Supports the historical significance of early fluorescence detection efforts.

Abstract

We examine the claim made by Hara et al. in 1969 of the observation of a 10^19 eV cosmic ray extensive air shower using the air fluorescence technique. We find that it is likely that fluorescence light was observed, confirming this as the first such observation. The work of Hara et al. and their friendly competitors at Cornell University paved the way for modern experiments like the Pierre Auger Observatory and the Telescope Array.