Origin of gamma-ray families accompanied by halos and detected in experiments with x-ray emulsion chambers

TL;DR

This paper explains the origin of gamma-ray families with halos observed in XREC experiments, showing they are mainly produced by protons and helium nuclei, and proposes using halos to estimate cosmic ray composition.

Contribution

It provides a detailed explanation of halos in gamma-ray families and demonstrates their use in estimating the primary cosmic ray composition.

Findings

Over 96% of halos are produced by protons and helium nuclei.

Simulation results match experimental properties of halos.

Halos can be used to estimate the fraction of protons and helium in cosmic rays.

Abstract

The phenomenon of gamma-ray families featuring halos that is observed in an experiment with x-ray emulsion chambers (XREC) in the Pamir experiment and in other XREC experiments is explained. The experimental properties of halos are analyzed via a comparison with the results of their simulation. It is shown that gamma-ray families featuring halos are predominantly produced (more than 96 % of them) by protons and heliumnuclei. This makes it possible to employ the experimental properties of halos to estimate the fraction of protons and helium nuclei in the mass composition of primary cosmic radiation.