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By L.G. Dedenko 1 , A.V. Glushkov 2 ,

Possible composition of the primary particles at ultrahigh energies observed at the Yakutsk array. By L.G. Dedenko 1 , A.V. Glushkov 2 , G.F. Fedorova 1 , S.P. Knurenko 2 , A.K. Makarov 2 , L . T . Makarov 2 , M.I. Pravdin 2 , T.M. Roganova 1 , A.A. Saburov 2 , I.Ye. Sleptzov 2

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By L.G. Dedenko 1 , A.V. Glushkov 2 ,

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  1. Possible composition of the primary particlesat ultrahigh energiesobserved at the Yakutsk array The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  2. By • L.G. Dedenko1, A.V. Glushkov2, • G.F. Fedorova1, S.P. Knurenko2, A.K. Makarov2, L.T. Makarov2, M.I. Pravdin2, T.M. Roganova1, A.A. Saburov2 , I.Ye. Sleptzov2 • 1. M.V. Lomonosov Moscow State University, Faculty of Physics and D.V. Skobeltsin Institute of Nuclear Physics, Moscow, 119992, • Leninskie Gory, Russian Federation • 2. Insitute of cosmic rays and aeronomy. Yakutsk, Russian Federation The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  3. Motivation • Testing the overall CR spectrum formation scenarios The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  4. The “dip” scenario of the overall CR spectrum formation • In the model of uniformly distributed extragalactic sources with a power law spectrum of generation, the proton flux must first decrease (a dip), then increase (a bump) and drop steeply (the GZK effect) [3, 4]. • [3] Berezinsky V S and Grigorieva S I 1988 Astron. Astrophys. 199 1 • [4] Berezinsky V S, Gazizov A Z, Grigorieva S I 2006 Phys. Rev. D 74 043005 The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  5. The “ankle” scenario • In the alternative “ankle” scenario [6] the extragalactic component dominates at energies above 1019 eV. The CR composition in this scenario is considerably • heavier at energies 1018 − 1019 eV • [6] Wibig T and Wolfendale W 2005 J. Phys. G: Nucl. Part. Phys. 31 255 The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  6. The scenario by Berezhko E G • The peak of rather heavy composition is predicted at energies ~ 1017 eV followed by • a sharp decrease of atomic number A within of the energy interval 1017 − 1018 eV. It is regarded as a signature of the transition from galactic to extragalactic CR. • The second peak of heavy elements in the atomic number distribution is predicted at energy ~ 1019 eV. So a profound increase of heavy composition should be observed within the energy interval 1018 − 1019 eV [5]. • [5] Berezhko E G 2009 Astrophys. J. 698 L138 The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  7. Study of composition • Standard approach: • The depth Xmax • of shower maximum • vs. E The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  8. BeforeLHC The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  9. AfterLHC The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  10. 23-d European cosmic ray symposium • Conclusion by T. Pierog, KIT, Karlsruhe, Germany (03.07.2012) • …light composition • is excluded • at high energies… The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  11. Question byAngela Olinte • The UHECR in CERN • Febrary 2012 • do we have pure protons anywhere??? The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  12. We believe the answer is • Yes The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  13. Alternative approach • THE FRACTION OF MUONS α • at 600 m from the shower core: α=sμ(600)/s(600) sμ(600) – a signal in the underground detector s(600) – a signal in the surfacedetector The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  14. Yakutsk array • The Yakutsk array includes • the surface scintillation detectors (SD),detectors of theVavilov-Cherenkovradiation, • underground detectors of muons (UD) • with suggested the threshold energy • ~1 GeV. • It was shown that the less energetic muons may hit the underground detectors. The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  15. Simulations • Simulations of the individual shower developmentin the atmosphere • have been carried out with the help of • the codeCORSIKA-6.616 • [7] Heck D, Knapp J, Capdevielle J-N et al. 1998 CORSIKA: A Monte Carlo Code to Simulate Extensive Air Showers • Report FZKA 6019 Forschungszentrum Karlsruhe The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  16. Simulations • Simulations • in terms of the models QGSJET2 • [8] Ostapchenko S S 2006 Nucl. Phys. Rev. B (Proc. Suppl.) 151 143 • and Gheisha 2002 • [9] Fesefeldt H C 1985 GHEISHA program Technical report PITHA 85-02, III Physikalisches Institut, RWTH Aachen. Physikzentrum • with the weightparameter ε=10-8(thinning). The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  17. Simulations • The program GEANT4 • [10] The GEANT4 Collab. Available from http://geant4.web.cern.ch/geant4/support/gettingstarted.shtml • has been used • to estimate signals • in the scintillation detectors • from electrons, positrons, gammas and muons • in each individual shower. The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  18. Study of the chemical composition • Muon density with energies above 1 GeV • for the primary protons with the energy E: • ρμ(600, >1 GeV)=a·Eb • Decay processes are decreasing for higher energies E. • b<1 The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  19. Study of the chemical composition • Muon density for the primary nuclei • with atomic number A • ρμ(600)=a·Ac·Eb • c>0 (c=1-b) • QGSJET2: b=0.895, c=0.105 • For Fe: • A0.105=1.53 The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  20. Study of the chemical composition • The signals are calibrated • in the surface detectors • s(600)=∆Es(600)/δEs(600) • and in the underground detectors • sμ(600)=∆Eu(600)/δEu(600) • ∆Es(600) and ∆Eu(600) • from the EAS particles • δEs(600) and δEu(600) • from the one vertical muon The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  21. Standard approach of energy estimation at the Yakutsk array • s(600) – the signal at 600 m • in the vertical EAS measured in • VEM’s • (VERTICAL EQUIVALENT MUON) • is used to estimate the energy E of EAS. The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  22. Standard approach of energy estimation at the Yakutsk array • DATA: • 1. The CIC method to estimate s(600) from data for the inclined EAS. • 2. The signal s(600) is calibrated with • help of the Vavilov-Cherenkov radiation • E=(4.6+-1.2)·1017·s(600)0.98, eV The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  23. Standard AGASA approach • Like AGASA: • 1. The CIC method to estimate s(600) from data for the inclined EAS. • 2. Calculation s(600) for EAS with • the energy E: • E=(3+-0.2)∙1017·s(600), eV The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  24. Spectrum • Data: • s(600)= E/((4.6+-1.2)·1017) • Simulation: • s(600)= E/((3.+-0.2)∙1017) • The simulated signal larger! • The fraction α is less! The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  25. Spectrum • Data: • s(600)= E/((4.6+-1.2)·1017) • Simulation: • s(600)= E/((3.+-0.2)∙1017) • The simulated signal larger! • The energy spectra are different • for these approaches. The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  26. Question • Is it possible • to increase the signal s(600) more, • to be able • to decrease the fraction α? The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  27. points ─ Yakutsk data circles ─ Yakutsk (calculation like AGASA) stars ─ PAO The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  28. Answer • In the formula • E=a·1017·s(600) • The coefficient a should be less than 4.6 and higher than 3 (difference by a factor 1.53). • The magnitude a=3 leads to • the maximal signal s(600) and • the minimal value of the muon fraction. The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  29. Results • Results of calculations The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  30. The fraction αof muons in EAS calculated in terms of the QGSJET-II and Gheisha-2002d models for the primary protons (solid line) and the primary iron nuclei (dashed line) and observed at the YaA [11] (dots with error bars) versus the energy E. The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  31. Question • Where are protons? The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  32. Another question Are the models used reliable? The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  33. At energies above 100 GeV • QGSJET2? • Kochanov A A, Sinegovskaya T S, Sinegovsky S I 2008 Astrop. Physics 30 219 Panov A D, Adams J H Jr, Ahn H S et al. 2007 Bull. Russ. Acad. Sci. Phys. 71 494 The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  34. The energy spectrum of vertical muons The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  35. Ratio R1 oftheobservedintensities (Δ − [21], - [22], ● − [23], ■ − [24], ○ − [25], + − [26]) of the vertical muons to the calculated muon intensity in terms of the QGSJET-II model vs. an impulse p of muons (A.Kochanov). The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  36. The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  37. Conclusion • Difference is increasing with the energy E • from 1.5 to 3 • at E=107 GeV. • We adopted the minimal value 1.5 • (A. Kochanov) The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  38. Below 100 GeV • GHEISHA? • Maris I C, Engel R, Arrido X et al. 2009 arXiv: 0907.0409v1 [astro-ph.CO] The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  39. Ratio R2 of muon densities calculated in terms of the FLUCA model to the intensty calculated with the Gheisha-2002d model vs. a distance r from a shower axis (R. Engel). The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  40. Conclusion • GHEISHA • gives the density of muons at 600 m • from the shower core • by a factor f3=1.1 lessthan the FLUKA • (R. Engel) The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  41. Corrected results The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  42. The fraction α of muons corrected due to results of [19, 21-26, 27, 29]. The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  43. Answer • We hope • that protons are observed The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  44. The dependence of the atomic number A on α • lnA= ln(α / αp ) / 0.105 • Here α is a measured value • and • αp is calculated for protons. The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  45. Dependence of the atomic number <ln A> on the energy E for YaA The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  46. CONCLUSION • We hope • that protons are observed in the energy interval • 3·1018 – 1019 eV • The new scenarios of the cosmic ray spectrum formation should be developed The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  47. Conclusions are model dependent • The Coulomb scattering of charged particle (electrons, positrons) • and the pt distribution of hadrons • (for muonscattering) should be taken into account precisely in calculations • of the lateral spread of these particles. The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  48. Acknowledgements. • Moscow authors thank G.T. Zatsepin LSS (grant 871.2012.2 ) for support. • Authors from Yakutsk thank RFBR grant 11-02-12193 ofim and by the state contract 16.518.11.7075 from the Department of science and education of Russian Federation. • for support. The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  49. Thank you for attention The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

  50. Dependence of the atomic number <ln A> on the energy E for various experiments: ● − [12], ■ − [9], □ − [33], ▲− [32]. The 23-European Symposium and the 32 Russian cosmic ray conference 3-7 July Moscow

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