Atridis Presentation Patra.ppt by xiaopangnv

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									Atmospheric shower simulation
   studies with CORSIKA


             ARISTOTLE UNIVERSITY OF THESSALONIKI

                        Physics Department




                         Atreidis George
High energy gamma ray astronomy at 100 GeV - 100 TeV


                                         High energy gamma rays photons.


                                         Coming from a distant source
                                          outside the Earth.

                                         Energies beyond those achievable
                                          in man-made accelerators.



    When a VHE gamma-ray enters the Earth's atmosphere, it generates an
     atmospheric shower.



       secondary charged particles             Cherenkov light
            Detection – Air showers
                    interaction




                   atmospheric
                      shower




                                          air shower
                                      telescopes (AST)



Cherenkov
 photons
    Atmospheric shower simulation with Corsika

   Primary particle – gamma ray photon.
   Three sets of showers. Every set consists of 10 showers.
   The primary particle energy is.


                       First set           10 TeV
                      Second set           40 TeV
                       Third set           70 TeV



   Zenith angle  20 deg.
   Azimuth angle  from -180 to 180 deg.
   Observation level  110m above sea level.
   The results are average values for each set of shower.
                           Coordinate system in Corsika

       The coordinates in CORSIKA are defined with respect to a Cartesian
        coordinate system.



 The positive x-axis points to the
  magnetic North.


 The positive y-axis points to
  the West.


 The z axis points upwards.



 The origin is located at sea level.
                                                        Θ  Zenith angle.

                                                        Φ  Azimuth angle.
                                                     Gamma particles distribution

                                                              Gamma particles distribution

                                      2,00E+04


                                      1,60E+04
              No of gamma particles




                                      1,20E+04


                                      8,00E+03


                                      4,00E+03


                                      0,00E+00
                                                 0      200           400            600      800     1000
                                                                            Depth (g/cm**2)

                                                                                10 TeV



      Starting point.
The top of the atmosphere.                                   Shower maximum
                                                          at a depth of 420 g/cm2.                    Observation level.
                                                                                                    110 m above sea level.
                                       Gamma particles distribution
                                                Gamma particles distribution


                        1,20E+05
No of gamma particles




                        8,00E+04



                        4,00E+04



                        0,00E+00
                                   0      200           400            600            800   1000
                                                              Depth (g/cm**2)

                                                         10 TeV   40 TeV     70 TeV



                               Big primary energy  more gamma particles.

                                        Shower maximum  goes deeper.
                                        Positrons distribution

                                           Positrons distribution

                  20000


                  16000
No of positrons




                  12000


                  8000


                  4000


                     0
                          0       200          400            600            800   1000
                                                     Depth (g/cm**2)

                                               10 TeV     40 TeV    70 TeV



                               Big primary energy  more positrons.

                                 Shower maximum  goes deeper.
                                     Electrons distribution

                                          Electrons distribution

                  25000


                  20000
No of electrons




                  15000


                  10000


                  5000


                     0
                          0        200       400            600            800   1000
                                                   Depth (g/cm**2)

                                              10 TeV   40 TeV     70 TeV




                               Big primary energy  more electrons.

                                 Shower maximum  goes deeper.
                                                     Lateral electron density
                                                                                              at observation level

                                                                   Lateral electron density
   for the three
primary energies
                                      8,00E-05
                                                                                    the density is
                   Electron density




                                      6,00E-05                                   reduced about 80%

                                      4,00E-05


                                      2,00E-05


                                      0,00E+00
                                                 0    500   1000    1500    2000    2500   3000      3500   4000   4500   5000
                                                                           Distance from core (cm)

                                                                        10 TeV       40 TeV       70 TeV




                                                       at a distance of 14 m from the core
                              Shower energy distribution
                                 Longitudinal energy distribution

               1,25E+04


               1,00E+04
Energy (GeV)




               7,50E+03


               5,00E+03


               2,50E+03


               0,00E+00
                          0     200        400           600        800   1000
                                                 Depth g/cm**2

                                                      10 TeV



      Continuing reduction in the shower energy.

      Energy loss  energy deposit into air.
                                         Energy deposit into air

                                   Energy deposit (primary particle 70 TeV)

               2000
                                                                            ionization
                                                                          energy deposit
               1600
                           cut energy for
Energy (GeV)




                          gamma particles                                    cut energy for
               1200
                            (0.15GeV)                                     electrons – positrons
                                                                               (0.15 GeV)
               800


               400


                 0
                      0            200         400            600               800        1000
                                                     Depth (g/cm**2)

                                               gammas     e+-ioniz     e+-cut
Number of charged particles at observation level
               Observation level 110 m above sea level

              Number of electrons - positrons at observation level

300


250
                                                        Ne>Np

200


150

100

50

 0
               1                             2                             3

                       Energy (TeV)   No of electrons    No of positrons



      More primary energy  more particles at observation level.
Locations of Cherenkov detectors in the simulation




        Number of Cherenkov detectors in x direction10
        Number of Cherenkov detectors in y direction 8
          Distance of detectors in x direction1200 cm
         Distance of detectors in y direction 1500 cm

          Length of the detector in x direction 80 cm

          Length of the detector in y direction 50 cm.
            Production of Cherenkov photons per 20g/cm2

                                                      Production of Cherenkov photons per 20 g/cm**2)

                                       1,60E+08

                                                                                        More Cherenkov photons
             No of Cherenkov photons




                                       1,20E+08                                         at the shower maximum.

                                       8,00E+07


                                       4,00E+07


                                       0,00E+00
                                                  0        200        400            600          800    1000      1200
                                                                              Depth (g/cm**2)

                                                                            Primary particle 70 TeV


      Starting point.                                                                                     Observation level.
The top of the atmosphere.                                                                              110 m above sea level.
                                          Total production of Cherenkov photons

                                                Cherenkov photons distribution

                           3,00E+09
 No of Cherenkov photons




                           2,00E+09

                                                                                                    observation
                                                                                                       level
                           1,00E+09




                           0,00E+00
                                      0       200       400        600          800   1000   1200
                                                              Depth (g/cm**2)

                                                          10 TeV   40 TeV   70 TeV


 The Cherenkov photons generated at all depths reach the observation level.

 At great depths the number of Cherenkov photons created are small, so the total
number tends to become stable.
                              Increase Cherenkov photons with energy
            • Number of Cherenkov photons arriving at the observation level.
                                                Total Cherenkov photons - energy

                            3,00E+09
  No of Cherenkov photons




                            2,00E+09




                            1,00E+09




                            0,00E+00
                                       0   10       20      30       40         50   60   70   80
                                                           Primary particle energy

                                                                    Cherenkov



 The increase in the Cherenkov photons in connection with the energy
 of the primary particle is almost linear.
Experiments in High Energy Gamma Ray Astronomy
       Telescope arrays for the detection of Cherenkov light


                                       H.E.S.S. experiment
                        Located in Namibia, near the Gamsberg mountain.
                              Energies from 100GeV to 100TeV.



                                       MAGIC experiment
                         Located in La Palma, one of the Canarian islands.
                                        Energies >100GeV.

                                        Mirror surface 236m2.


                                       VERITAS experiment
                            Located in southern Arizona of the USA.

                                 Energies from 50GeV to 50TeV.

                              An array of four 12m optical reflectors.
             New Experiment - CTA

                                           Location
                                      Not yet determined.

                                     Three telescope types
                         Four 24 m telescopes with 5o field-of-view.
                    23 telescopes of 12 m diameter with 8o field-of-view.

                   32 telescopes of 7 m diameter with a 10o field-of-view.

                                      Telescopes distribution
         The telescopes are distributed over 3 km2 on the ground.

 The effective collection area of the array is considerably larger than this at
  energies beyond 10 TeV.

                                    Cost

Array layout has a nominal construction cost of 80 M€ and meets the
 main design goals of CTA.
                                Conclusions

                  The high-energy range above 10TeV

For very high primary particle energy ~100TeV the maximum of the shower
goes deeper and the Cherenkov light reaches its ultimate intensity at about
800 g/cm2 or ~2 km in altitude.
                                      So




The observation level                                   The detectors should be
  should be lower.                                       extended more widely.

                           Two implementation options




   either a large number                                or a smaller number
    of small telescopes                                 of larger telescopes
Thank you for your time

								
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