a chilingarian g hovsepyan cosmic ray division alikhanyan physics institute armenia
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A.Chilingarian, G.Hovsepyan Cosmic Ray Division, Alikhanyan Physics Institute, Armenia. Size and Energy Spectra of incident cosmic radiation obtained by the MAKET - ANI surface array on mountain Aragats. ( Final results from MAKET-ANI detector) ‏.

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a chilingarian g hovsepyan cosmic ray division alikhanyan physics institute armenia
A.Chilingarian, G.Hovsepyan

Cosmic Ray Division, Alikhanyan Physics Institute, Armenia.

Size and Energy Spectra of incident cosmic radiation obtained by the MAKET - ANI surface array on mountain Aragats. (Final results from MAKET-ANI detector)‏

slide2
MAKET-ANI detector designed to measure Extensive Air Showers (EAS) from Primary Cosmic rays (PC) with energies 105 – 108 GeV. Detector position: 3200m above see level on Mt. Aragats, Armenia. Geographic location: 40.5oN, 44.2oE
slide3
Consist – 92 plastic scintillation detector 68 with 1m2 area, and 24 – 0.09 m2.
  • 19 of 1m2 area detectors for fast timing system.
    • Two types triggers are used:
        • for density detectors 7 from 11
        • for fast timing system 4 from 9
  • Effective area for EAS collection ~900m2 for Ne >105
slide4
is the normalization factor (Hayakawa, 1969, Aseykin , 1979 )‏

rm =118 m

event { Ne, S, X0,Y0,Θ, φ}

  • angular accuracy not worse
  • than ~1.50 for zenith θ, and for the azimuth ones Δφ ~ 50
  • for the showers within 150 < θ < 450 .

The reconstructed shower size errors

(including systematic) are less than ~13% at Ne =105 and quickly decrease with the rise of shower size.

The accuracy of the reconstructed EAS core position within the collected area Seff =880m2 is less than 1 m

The errors of reconstructed age para-meter are less than ~9% at Ne =105.

slide5
From 1997 to 2004 ~1.2 ∙ 107 shower triggers were registered. The total exposition time was ~1.42∙108 s. Installation Stability of the operation time.

additional restrictions on the EAS triggers Ne ≥ 10 5, 0.3 < s < 1.7,

θ ≤ 46.8 o, {X0, Y0}  Seff reduce the total number of events by an

order of magnitude to a value of ~ 1.3 ∙ 106.

slide6
MAKET-ANI measured EAS Size Spectra in comparison with KASCADE data .

Both spectra for Sec uniform zenith angles interval are shown..

The line indicate EAS size attenuation versus of slant depth of atmosphere.

The attenuation length by MAKET-ANI data is equal Λ=211±38 g/cm2, for KASCADE data Λ=197±13 g/cm2 and by joint analyses - Λ=194±14 g/cm2.

The difference of spectral indexes before and after knee is equal

Δγ = - 0.45±0.06

EAS size spectra approximated by

slide7
Primary CR simulation by CORSIKA (562,QGSJet01,NKG mode) code was done. For H, He, O, Si, Fe primaries 106 events and E0≥105 GeV for each of them generated . The atmosphere depth is 700g/cm2

Yield function from simulated primaries after:

  • trigger conditions;
  • response function of installation,

is obtained.

The response of the MAKET-ANI detector on simulated “light” (p+He ) and “heavy” (Si+Fe) induced showers,versus primary energy; shower selection criteria: Ne≥105, θ≤30o (closed symbols ), Ne≥105, 30o≤θ≤45o (open symbols)

slide9
Primary light component (p+He) measured by the MAKET-ANI detector with comparison to the results from KASCADE, EAS-TOP, HEGRA, EAS-TOP+MACRO, TIBET and primary protons spectra approximations obtained by the single hadrons fluxes EAS-TOP and KASCADE. (All data based on CORSIKA QGSJet01 version). The direct balloon measurements by ATIC-2 and JACEE at 102 – 105 GeV also presented.
slide10
The energy spectrum of the “heavy” nuclei group measured by the MAKET-ANI detector along with spectra from KASCADE , EAS-TOP+MACRO and ATIC-2 . The solid line is a power function approximations
conclusions
Conclusions.
  • From 1997 up to the end of 2004 the MAKET – ANI experiment has taken data with exposition time of ~1.42∙108 s. The total number of the registered shower events was ~1.2∙107. A smaller sample of the data (~1.3∙106 ) with Ne ≥105 and θ ≤46.80 was used for the in-depth analysis of the LDF and size spectra. By 7.2∙105 near the vertical (θ ≤300) EAS were obtained the energy spectra of light and heavy nuclei groups.
  • The obtained dependence of the shower age on shower size pointed to the weighting of the primary flux mass composition after the knee of the “all particle” spectrum;
  • The size spectra show evidence of a “knee” at shower size ~106 particles. As the zenith angle enlarges, the knee position is moving to smaller sizes, according to the EAS attenuation length =211±38 g/cm2.
slide12
The difference of the power low spectra before and after the knee is constant with high precision Δγ = 0.45 ±0.06.
  • The estimated energy spectrum of the light mass group of nuclei shows a very sharp knee: ∆γ ≈ 0.9, compared to ∆γ ≈ 0.4 for the all-particle energy spectra.
  • The energy spectrum of the heavy mass group of cosmic rays shows no knee in the energy interval of 1015 –1016 eV.
  • The mentioned results are consistent with the nonlinear kinetic theory of CR acceleration in SNR shells

Thank You !

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