gamma-Families with Halos Observed by X-ray Emulsion Chamber in EAS and the Estimate of the p+He Fraction in Primary Cosmic Rays at E0 = 1-100 PeV

TL;DR

This study analyzes gamma-families with halos observed via X-ray emulsion chambers to estimate the p+He fraction in primary cosmic rays, revealing a consistently mixed composition across 1-100 PeV energies.

Contribution

It provides the first detailed analysis of halo events in gamma-families and estimates the p+He fraction in cosmic rays at PeV energies using X-ray emulsion chambers.

Findings

The halo nature aligns with the standard nuclear interaction model.

The primary cosmic ray composition remains mixed from 1 to 100 PeV.

The p+He fraction was quantitatively estimated in this energy range.

Abstract

The experimental gamma-families in which events called "halos" were detected using X-ray emulsion chambers (XRECs) of the PAMIR experiment are described. The halo nature is explained within the standard model of nuclear interactions. Based on events with halo, the fraction of p+He in primary cosmic rays (PCR) was estimated. It is shown that the PCR mass composition remains mixed in the range E0 = 1-100 PeV.