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

• A.Chilingarian, G.Hovsepyan
• Cosmic Ray Division, Alikhanyan Physics
  Institute, Armenia.

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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
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• 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
  gt105

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is the normalization factor (Hayakawa, 1969,
Aseykin , 1979 )?
rm 118 m
event Ne, S, X0,Y0, T, f

• angular accuracy not worse
• than 1.50 for zenith ?, and for the azimuth
  ones ?f 50
• for the showers within 150 lt ? lt 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.
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From 1997 to 2004 1.2 107 shower triggers
were registered. The total
exposition time was 1.42108 s. Installation
Stability of the operation time.
additional restrictions on the EAS triggers Ne
10 5, 0.3 lt s lt 1.7, ? 46.8 o, X0, Y0 ?
Seff reduce the total number of events by
an order of magnitude to a value of 1.3 106.
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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
?21138 g/cm2, for KASCADE data ?19713 g/cm2
and by joint analyses - ?19414 g/cm2. The
difference of spectral indexes before and after
knee is equal ?? - 0.450.06 EAS
size spectra approximated by
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L D F

• The comparison the experimentally obtained LDF
  functions to the theoretical ones
• CORSIKA 562 (QGSJet01, NKG mode) was used,
• for H, He, O, Si, Fe primaries
  106 events and E0105Gev for each of them
  generated
• we assume the following mass composition and
  energy spectra of the primary galactic cosmic
  rays (so called normal mass composition)
  (35H, 25He, 14O, 15 Si, 10 Fe)
• knee position E knee Z E0, E0 3 10
  15 eV, Z is the primary nuclei charge
• energy spectra index ? 1 -2.7 before knee
  and, ?2 -3.1 after knee for all nuclei.

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The dependence of the measured age parameter on
shower size in comparison to several models of
primary flux composition is presented To outline
the boundaries of the extreme cases we use pure
proton and pure iron nuclei fluxes. More
realistic assumptions about energy dependence of
the primary composition are between these extreme
assumptions

• 1. Rigidity dependent normal composition with
  knee position at E knee Z 3 10 15 eV
• 2. The same as in point 1, but with fixed knee
  position at E knee 3 10 15 eV for each group
  of nuclei
• 3. "Heavy " composition (5 P, 5 He, 10 O, 10
  Si, 70 Fe), knee position at E knee Z 3
  1015 eV.
• For all 3 models the energy spectra index ? 1
  -2.7 before knee and, ?2 -3.1 after knee
  for all nuclei. The first model (normal
  composition) fits experimental data quite well,
  (the value of the test equals ?2 1.23). At the
  same time we can exclude the options 2 (?2 8.8)
  and 3 ( ?2 31.1 ).

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Primary CR simulation by CORSIKA
(562,QGSJet01,NKG mode) code was done. For H,
He, O, Si, Fe primaries 106 events and E0105
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 (pHe ) and heavy (SiFe)
  induced showers, versus primary energy shower
  selection criteria Ne105, ?30o (closed symbols
  ), Ne105, 30o?45o (open symbols)

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Primary light component (pHe) measured by the
MAKET-ANI detector with comparison to the
results from KASCADE, EAS-TOP, HEGRA,
EAS-TOPMACRO, 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.
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The energy spectrum of the heavy nuclei group
measured by the MAKET-ANI detector along with
spectra from KASCADE , EAS-TOPMACRO and ATIC-2 .
The solid line is a power function
approximations
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SPECTRUM OF COSMIC RAYS, PRODUCED IN SUPERNOVA
REMNANTSE.G. Berezhko, H.J.Völk April 16,
2007
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Conclusions.

• From 1997 up to the end of 2004 the MAKET ANI
  experiment has taken data with exposition time of
  1.42108 s. The total number of the registered
  shower events was 1.2107. A smaller sample of
  the data (1.3106 ) with Ne 105 and ? 46.80
  was used for the in-depth analysis of the LDF and
  size spectra. By 7.2105 near the vertical (?
  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 21138 g/cm2.

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• The difference of the power low spectra
  before and after the knee is constant with high
  precision ?? 0.45 0.06.
• The estimated energy spectrum of the light
  mass group of nuclei shows a very sharp knee ??
  0.9, compared to ?? 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 !