Gamma-ray families with halos: Main characteristics and possibilities of using them to estimate the p+He fraction in the mass composition of cosmic rays at energies 1–100 PeV

A.S Borisov,A.E Morozov,M.G Kogan,R.A Mukhamedshin,G.P Shoziyoev,S.E Pyatovsky,S.B Shaulov,M.D Smirnova,V.G Denisova,V.S Puchkov,Z.M Guseva,E.A Kanevskaya,B Pattison

doi:10.1051/epjconf/201714519008

Abstract

Gamma-ray families with halos: Main characteristics and possibilities of using them to estimate the p+He fraction in the mass composition of cosmic rays at energies 1–100 PeV

Highlights

The X-ray emulsion chamber (XREC) (Pamir) (Fig. 1) represents a solid-state track chamber installed at the Pamirs at an altitude of 4400 m a.s.l
The MC0 model designed for simulation of hadron-hadron and hadron-nucleus interactions in Extensive Air Showers (EAS) reproduces rather well the characteristics of the XREC experimental data and high-xF LHC data
Analysis of XREC (Pamir) experiment results using MC0 and QGSJ models shows that ≥ 90% of the registered events are formed by the proton and helium (p+He) component

Summary

Dependence on E0 of the fraction of γ -ray families with halos

The dominant part of the halo-containing γ -ray families is formed by protons (Fig. 3). Calculations revealed that 83% of all events are produced by primary protons, 13% are produced by helium nuclei and not more than 4% are produced by heavier nuclei This conclusion is almost independent of the model and provides a possibility to estimate the proton fraction in PCR in the range of E0 = 1–100 PeV. MC0-based calculations show that at E0 > 5 PeV the efficiency of formation of the halo-containing γ -ray families by protons is four times higher than by He nuclei (Table 3). This explains the preferential registration with XREC of such γ -ray families produced by protons

Average size of γ -ray families in the XREC experiment

Findings

Conclusions