UNDERGROUND MUON HALL

150 (200 since 2012) plastic scintillators (1×1×0.05 m³, muon carpet) disposed under 2500 g/cm² of rock at the center of EAS ground-based array to detect shower muon component with energy more than Eμ ≥ (4.5 GeV)/cosθ. The expected accuracies of EAS truncated muon size reconstruction (ΔNμ /Nμ) within Rμ<50 m radius from EAS core, are about 20-35% for the shower muon size range 105≲Nμ≲103 respectively. Muon carpet allows to select the high energy (Eγ≳1014 eV) gamma showers (using no-muon signal events), the multicore EAS muon events originated from hard jet productions at E₀≳1016 eV, and to improve the efficiency of EAS inverse problem solution for the reconstruction of primary nuclei energy spectra in the knee region,    .


UNDERGROUND MUON HALL
(Muon Carpet)

    The right panel represents the layout of 150 plastic (1×1×0.05) m³ scintillators deployed in the horizontal plane of Underground Muon Hall for 2003-2011 (hollow square symbols) along with additional 50 scintillators (cross-filled square symbols) after GAMMA array upgrading in 2012. Cross symbol on the center of detector layout is the origin (x₀=0, y₀=0) of GAMMA array coordinate system in the XY plane. Detected muon energy threshold is Eμ≳ (4.5 GeV)/cosθ.
    The enlarged shower muon detection area in the Underground Muon Hall of the GAMMA array improved the primary nuclei resolutions for the reconstruction of energy spectra for primary H, He, O, Fe nuclei and the discrimination of ultra-high energy primary γ-ray initiated showers detected by the GAMMA array. The last results and preliminary shower muon truncated size spectra are presented below,

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CURRENT RESEARCH (2015)

arXiv:1405.5472, Physical Review D 89, 123003 (2014)

SHOWER SPECTRA FOR SEC(Θ) < 1.6


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RESULTS FOR 2007-2009

  • Romen M. Martirosov, Samvel V. Ter-Antonyan, Anatoly D. Erlykin, Alexandr P. Garyaka, Natalya M. Nikolskaya, Yves A. Gallant and Lawrence W. Jones, "Galactic diffuse gamma-ray flux at the energy about 175 TeV", arXiv:0905.3593, Proceedings of 31-th International Cosmic Ray Conference, Lodz, Poland (2009).

  • A.P. Garyaka, R.M. Martirosov, S.V. Ter-Antonyan, A.D. Erlykin, N. Nikolskaya, Y.A. Gallant, L. Jones, and J. Procureur, "All-particle primary energy spectrum in the 3-200 PeV energy range" Journal of Physics G: Nuclear and Particle Physics, 35 (2008) 115201. available from: http://stacks.iop.org/0954-3899/35/115201 or arXiv:0808.1421.

  • A.P. Garyaka, R.M. Martirosov, S.V. Ter-Antonyan, N. Nikolskaya, Y.A. Gallant, L. Jones, J. Procureur, "Rigidity-dependent cosmic ray energy spectra in the knee region obtained with the GAMMA experiment". Astroparticle Physics, Volume 28, issue 2 (2007) p. 169 / available from: arXiv:0704.3200.

    • PRELIMINARY DATA (2005)

  • S.V. Ter-Antonyan, R.M. Martirosov, A.P. Garyaka, V. Eganov, N. Nikolskaya, T. Episkoposyan, J. Procureur, Y. Gallant, L. Jones: "Primary Energy Spectra and Elemental Composition. GAMMA Experiment". astro-ph/0506588 (2005).

  • S.V. Ter-Antonyan, Y.A. Gallant, A.P. Garyaka, L.W. Jones, R.M.Martirosov, N.M. Nikolskaya, J. Procureur: "All-particle primary energy spectrum in the knee region" Proceedings of 29th ICRC, Pune, India, (2005)     .

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First Results (GAMMA-2004)

GAMMA data:
Detected EAS muon truncated size spectra at different EAS sizes and different interaction models (presented to GAMMA workshop 2004).

The "strange" behavior of Ne-Nm plot at Nch>107 (workshop GAMMA).

Example of the multicore EAS event detected by GAMMA underground muon scintillator carpet. 

According to the quark-parton model of particle production with large transverse momenta in hadron interactions, the events with large p⊥ are due to hard scattering of quark-parton (gluons) which then are hadronized in the form of jets. It follows from the dynamics of these processes that the jets produced by spectator quarks are located on the interaction axis, and the other two jets (or a jet and gamma-quanta) generated from the hard collision of quarks (or a quark with gluon) emit under large transverse momenta. If the jet longitudinal momentum xjet > 0.05, and the transverse momentum p⊥ >>1 GeV/c, then at the energy of collision ~1015 eV if a cosmic ray nucleon with an air atom nucleus, the hadronized hard jet from the fragmentation region will be a source of a subcore of EAS whose major core is produced by a jet of spectator quarks.
Presented event corresponds to primary energy E₀≃7×1016 eV, xjet ~ 0.05 and p⊥≳20 GeV  (Samvel Ter-Antonyan Workshop GAMMA2004).