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Arreglo EAS-UAP para el Estudio de Rayos Cósmicos alrededor de 10 15 eV

Arreglo EAS-UAP para el Estudio de Rayos Cósmicos alrededor de 10 15 eV. Humberto, Salazar, Oscar Martínez, César Alvarez, L. Villaseñor * + Estudiantes del Grupo de la FCFM-BUAP

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Arreglo EAS-UAP para el Estudio de Rayos Cósmicos alrededor de 10 15 eV

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  1. Arreglo EAS-UAP para el Estudio de Rayos Cósmicos alrededor de 1015 eV Humberto, Salazar, Oscar Martínez, César Alvarez, L. Villaseñor* + Estudiantes del Grupo de la FCFM-BUAP Facultad de Físico-Matemáticas, Benemérita Universidad Autónoma de Puebla, Apartado Postal 1364, Puebla, Pue., 72000, México *On leave of absence from Institute of Physics and Mathematics, University of Michoacan, Morelia, Mich., 58040, México Coloquio del Grupo de Altas Energías CINVESTAV-IPN D.F. Sept. 20, 2005

  2. At an energy of approximately3 PeVthe spectral index steepens (“knee”). • To understand thereason for the knee, one must understand thesource, acceleration mechanism, and propagationof cosmic rays. • First-order Fermiaccelerationhas a cutoff energy (protons to 1014 eV and Iron to 3 x 1015 eV) • Observing the mass composition of cosmicrays at the knee therefore provides an importantclue to the origin of cosmic rays.

  3. Source • Supernova shock-wave Fermiacceleration is correct + Unknown mechanism i.e., rotating compact magnetic objects (neutron stars or black holes) at higher energies = kink due to overlap between the two mechanisms with progressive change in chemical composition as the knee is approached. Propagation • Smooth energy distribution up to the highest cosmic-ray energies with unknown loss mechanism beginning at about 1015 eV. • Measuring the chemical composition of the cosmic rays at 1015 eV cantest the different explanations.

  4. PMT Electron tubes 9353 K EAS Array • Area: 4000 m^2 • 10 Liquid Ssintillator Detectors (Bicron BC-517H) • 4 Water Cherenkov Detectors PMT EMI 9030 A

  5. 2200m a.s.l., 800 g/cm2. Located at Campus Universidad Autonoma de Puebla • Hybrid: Liquid Scintillator Detectors and water Cherenkov Detectors • Energy range 10^14- 10^16 eV

  6. Trigger: Coincidence of 3-4 central detectors (40mx40m) NIM y CAMAC. DAQ System • Use digital Osciloscopes • as ADCs. • Rate: 80 eventos/h

  7. Calibration DAQ System • Rate: 250 events/m2/s

  8. Use CAMAC scalers to measure rates of single partícles on each detector. Day-night variations <10% Monitoring s/mean around 3%

  9. Calibration

  10. ~74 pe

  11. LabView based DAS

  12. MPV of EM peak = 0.12 VEM i.e. around 29 MeV, i.e., dominated By knock-on + decay electrons

  13. Stopping muon at 0.1 VEM Decay electron at 0.17 VEM = 41 MeV Crossing muon at 1 VEM Alarcón M. et al., NIM A 420 [1-2], 39-47 (1999).

  14. Muon/EM Separation Muons deposit 240 MeV in 1.20m high water and only 26 MeV in 13 cm high liquid, while electrons deposit all of their energy i.e., around 10 MeV. Therefore for 10 Mev electrons we expect: Mu/EM=24 for Cherenkov Mu/EM=2.6 for Liq. Scint. Cherenkov Liquid Scint

  15. Arrival direction sinq sinf = d/c(t2-t1) Data Analysis

  16. Angular distribution inferred directly from the relative arrival times of shower front in good agreement with the literature: cosp sen 

  17. Lateral Distribution Functions Data Analysis The shower core is located as the center of gravity. • Energy Determination EAS-TOP, Astrop. Phys, 10(1999)1-9

  18. Ne, obtained for vertical showers. The fitted curve is Ik (Ne/Nek)-g, gives g=2.44±0.13 which corresponds to a spectral index of the enerfy distributions of g=2.6

  19. Muon/EM Separation Muons deposit 240 MeV in 1.20m high water and only 26 MeV in 13 cm high liquid, while electrons deposit all of their energy i.e., around 10 MeV. Therefore for 10 Mev electrons we expect: Mu/EM=24 for Cherenkov Mu/EM=2.6 for Liq. Scint. Cherenkov Liquid Scint

  20. Mass CompositionHybrid Array Solution:

  21. Iterations Start with Ne=82,300 Nmu = 32700 E0 = 233 TeV Iterations End with Ne=68000 Nmu = 18200 E0 = 196 TeV

  22. Mass CompositionNon-Hybrid Array Do a three parameter fit to :

  23. Two Identical types of Cherenkov Detectors one filled with 1.20 m of water and the other with 0.60 m, i.e., VEMC’=0.5VEMC Mass CompositionNon-Hybrid but Composite Array i.e., do independent fits of rEM and rmuon to NKG and Greissen LDF, respectively, where:

  24. Conclusions We have checked the stability and performed the calibration of the detectors. We have measured and analyzed the arrival direction of showers. We determine the energy of the primary by measuring the total number of charged particles obtaining by integration of the fitted LDF. Study of Muon/Electromagnetic ratio is underway:

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