No muon excess in EAS at 100 PeV: results of EAS-MSU experiment - PowerPoint PPT Presentation

No muon excess in EAS at 100 PeV: results of EAS-MSU experiment Mikhail Kuznetsov In collaboration with S. Troitsky, G. Rubtsov, I. Karpikov (INR RAS) Yu. Fomin, N. Kalmykov, G. Kulikov and V. Sulakov (SINP MSU) Astropart.Phys. 92, 1 (2017) ICRC-2017, Busan, July 2017 Mikhail Kuznetsov No muon excess in EAS at 100 PeV: results of EAS-MSU experiment

Outline Motivation: study of muons in extensive air showers (EAS) The EAS-MSU experiment The method of muon excess description Results & Conclusions Mikhail Kuznetsov No muon excess in EAS at 100 PeV: results of EAS-MSU experiment

Motivation: study of muons in EAS Muon content of EAS as a tool for study the hadronic interactions at high energies. At highest energies ( E CR > 10 19 eV ) the presence of “muon excess” is well established. The cosmic-ray energy ∼ 10 19 eV correspond to ∼ 100 TeV LHC energy. The “muon excess” is the overabundance of muons in a real EAS comparing to high-energy hadronic models predictions. Published results for EAS muon content in various parameter regions Experiment X , E , eV E µ , r / r 0 θ µ excess g/cm 2 GeV 10 17 − 10 18 HiRes-MIA 860 � 0 . 85 � 10 N/A yes � 10 19 PAO 880 � 1 � 10 70 ◦ yes � 10 19 Yakutsk 1020 � 1 � 10 45 ◦ yes 10 15 − 10 17 13 ◦ mean IceTop 680 � 0 . 2 � 3 no For TA muon results see R. Takeishi poster on 18.07 Mikhail Kuznetsov No muon excess in EAS at 100 PeV: results of EAS-MSU experiment

EAS-MSU experiment 60 ○ ● 40 ○ ● ○ ● ○ ○ 20 ■ ■ ■ ■ ■ ■ ■ ○ ○ ○ ■ ■ ■ ○ ○ ○ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Y,m ■ ● ● ■ ■ 0 ■ ● ■ ■ ■ ○ ○ ● ■ ■ ● ○ ○ ■ ■ ○ ○ ○ ■ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ - 20 ○ ○ ○ ○ ● ● ○ - 40 ○ ● - 60 - 60 - 40 - 20 0 20 40 60 X, m 77 surface detectors with Geiger counters, 29 scintillators for timing Effective for EAS with ∼ 0 . 5 km 2 area 10 15 . 5 � E primary � 10 17 . 75 eV Underground muon detector ( E µ ≥ 10 GeV) ∼ 1500 days of operation (1982-1990) Total ∼ 10 6 EASes detected Mikhail Kuznetsov No muon excess in EAS at 100 PeV: results of EAS-MSU experiment

Monte-Carlo & reconstruction I Full Monte-Carlo simulation Yu. Fomin et al., JINST 11, T08005 (2016) CORSIKA (p + Fe primaries) + EGS4 + Fluka + QGSJetII 10 15 . 5 ≤ E primary ≤ 10 17 . 75 eV , dN dE ∼ E − 3 . 1 avg. of PDG 2014 spectra ⇓ C ++ code simulating the facility ⇓ Reconstruction with the same code as for data Mikhail Kuznetsov No muon excess in EAS at 100 PeV: results of EAS-MSU experiment

Monte-Carlo & reconstruction I Full Monte-Carlo simulation Yu. Fomin et al., JINST 11, T08005 (2016) CORSIKA (p + Fe primaries) + EGS4 + Fluka + QGSJetII 10 15 . 5 ≤ E primary ≤ 10 17 . 75 eV , dN dE ∼ E − 3 . 1 avg. of PDG 2014 spectra ⇓ C ++ code simulating the facility ⇓ Reconstruction with the same code as for data SD reconstruction parameters N e — number of charged particles All particle lateral distribution function S — shower age parameter (LDF) � � ( S + α ( r / r 0 ) − 2) θ, φ — shower zenith and ⇒ r ρ ( S , r ) ∼ N e · × r 0 azimuthal angle � � ( S + α ( r / r 0 ) − 4 . 5) r r 0 + 1 R — shower core distance from the array center r 0 ≃ 80 m — is the Moliere radius Mikhail Kuznetsov No muon excess in EAS at 100 PeV: results of EAS-MSU experiment

Monte-Carlo & reconstruction II Selection cuts 1 σ accuracy of the reconstruction for N e > 2 · 10 7 ( E MC � 10 16 . 5 eV for p / Fe mix ∆ ψ < 1 . 1 ◦ — arrival direction p-primaries) R < 240 m ∆ R < 5 . 7 m — axis position θ < 30 ◦ ∆ N e / N e < 0 . 17 — number of charged particles 0 . 3 < S < 1 . 8 The efficiency is � 95% Total exposure is 7 . 7 × 10 6 km s sr , 809 events selected Primary energy reconstruction 8.8 × × × × × + × × × × × × + × × × × × × + × × + × × × × × × × × × × + + + × × + × × + + × × × × × × + + + × × × × × × × × × × × × × × × + + + + + + × × × × + × × + + + + × + × + + 8.6 × × × × × × + × × × + + × + + + × + + + + + × × × × × × × × × × × × × × × + + + × × × × × × × × × × + + + + + + + + + + + + + + + + + + × × × × × × × × × × × + × + + + + For best fit p / Fe mix: × × × × × × × × × + + + + + + + + + + + + + + + + + × × × × × × × × × × × × × × × × × × × × × × × × × × × × × × + × × × × × + × × × × × × × × × × × × × × × × × × × × × × × × × × × + × × × + + + × × × × × × × × × × × × + × + + + + × × × × × × × × + + + + 8.4 × × × × × × × × × × × × × × + + × × × × × + × × × + + + + × × × + + + + + × × × × × × × × × × × × × × × × × × × × × × × × + + + + + + + + + + × × × + × × + × × × × × × × × × × × × × × × × + + + + × + × × × × + × × + × + × × × × × × × + × × × + × × × × + + × × + + + + + log( E / GeV ) = 0 . 65 + log 10 N e × × × × × + + + + + + + log 10 E / GeV × × × × × × × × × × × × ×× × × × × × × × × × × × × × + + × + + × + + + + + + + + + + + + + + + + × × × + × + × × × + + + × × × + + × × × × + × + × + + + + + + + + + + + + × × × × × × × × × × × × × × × × × × × × + × × + + + + + × + × + + + 8.2 + × × × × × + + + + + + + + + + + × × × × + + + × × × × × + × + + + + + + + × × × × × × ×× × × × × × × + + + + + + + + × × × × × × × + × × × + + + + + + × + + × × × × × × × × + × × + × + + + × × × × × × × × × × × × × × × × × × × × × × × × × × + + × × × + + + + + + + + + + + + + + + × × × × + × × × × × × × × × × × × × + × × × × × + + + + + + + + + + + + + + + + + × × × × + × × × × × + × + × × + × × × × × × × + × × × × × + + + × + + + + + + + + ⇓ × × × × × × × × × × × × × × × × × × × × × × × × × × × × × × × × × × × × × + × + + + + + + + + + + + + + + + + + + + + + + + + + × × × × × × × × × + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + × × × × × × + × + × + + × × × + + × + + 8.0 × × × + + + + + + + + + + + + + + + × + + + × × × + + × + + + + + + + + × × × + + + + + + + + + + + + + + + + + + + + + + ++ + + + + + + + + + + + + + + + + + ++ + + + + + + + + + + + ∆ E / E < 0 . 41 (1 σ ) + + + + + + + + + + + + 7.8 + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 7.6 + + + + + + 7.4 7.6 7.8 8.0 8.2 8.4 log 10 ( N e ) Mikhail Kuznetsov No muon excess in EAS at 100 PeV: results of EAS-MSU experiment

Monte–Carlo: SD chemical composition Chemical composition from the fit of SD data over LDF S -parameter. � � ( S + α ( r / r 0 ) − 2) � � ( S + α ( r / r 0 ) − 4 . 5) r r ρ ( S , r ) ∼ N e · r 0 + 1 × r 0 Data vs. MC p and MC Fe Data fitted with MC p/Fe mix 400 500 400 300 numberof events numberof events 300 200 200 100 100 0 0 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 0.5 1.0 1.5 S S N p N Fe N p + N Fe = 43% , N p + N Fe = 57% Cf. the results of other experiments. KASCADE-Grande: 41% p , 59% Fe . Tunka-133: 49% p , 51% Fe . Mikhail Kuznetsov No muon excess in EAS at 100 PeV: results of EAS-MSU experiment