Atmospheric gamma-ray observation with the BETS detectorfor calibrating atmospheric neutrino flux calculations

TL;DR

This study measures atmospheric gamma-rays at high altitudes to evaluate and improve nuclear interaction models, which are crucial for accurate atmospheric neutrino flux calculations.

Contribution

It provides empirical gamma-ray data at balloon altitudes and mountain levels to test and compare nuclear interaction models used in neutrino flux predictions.

Findings

Lund Fritiof1.6 model poorly fits observed data.

Lund Fritiof7.02 and dpmjet3.03 models agree better with observations.

Results aid in refining atmospheric neutrino flux calculations.

Abstract

We observed atmospheric gamma-rays around 10 GeV at balloon altitudes (15~25 km) and at a mountain (2770 m a.s.l). The observed results were compared with Monte Carlo calculations to find that an interaction model (Lund Fritiof1.6) used in an old neutrino flux calculation was not good enough for describing the observed values. In stead, we found that two other nuclear interaction models, Lund Fritiof7.02 and dpmjet3.03, gave much better agreement with the observations. Our data will serve for examining nuclear interaction models and for deriving a reliable absolute atmospheric neutrino flux in the GeV region.