status of cosmic rays physics at the knee andrea chiavassa università and infn torino now 2006...
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Status of Cosmic Rays Physics at the Knee
Andrea ChiavassaUniversità and INFN Torino
NOW 2006Otranto 9-16 September 2006
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1 particle m-2 s-1
Knee1 particle m-2 year-1
Ankle1 particle km-2 year-1
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Hypotesis on the origin of the Knee
• Reach of maximum energy at the acceleration in Galactic Sources? SNR (Eknee Z)
Cannonball (Eknee A)• Diffusion: Escape of particles from
Galactic Magnetic fields? (Eknee Z) • Unknown effects of interaction in the
development of Extensive Air Showers? (Eknee A)
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Measurement that can separate different hypotesis
• Chemical Composition of CR• Anisotropy• Single Element Spectra
EAS Experiments• Measurements of different components of EAS to determine: Energy, Mass, Arrival Direction
• High Statistics • Data Interpretation strictly connected with MC
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Experiment X (g cm-2)
CASA-MIA
BLANCA
870 Scintillators Ne NCerenkov Light Xmax
HEGRA 790 Scintillators Ne
Cerenkov Light N Xmax
EAS-TOP 810 Scintillators Ne
Streamer Tubes N>1 GeV Nh
Cerenkov Light N
KASCADE 1020 Scintillators Ne N (E>230 MeV)
Calorimetr Nh Eh
MWPC N (E>2400 MeV)
TIBET AS 606 Scintillators Ne
Emulsion -families
TUNKA 25 950 Cerenkov Light N Xmax
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The spectra of all the components of EAS show the “Knee”: Ne, N, Eh
KASCADE
EAS-TOP
N
Ne
Eh
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Spectra of “light” and “heavy” elements of Cosmic Rays
KASCADEOnly the spectrum obtained using “electron rich” events shows the change of slope
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Energy Spectrum of Single Elements
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Spectra of light elements show the kneePosition of the knee vary with primary elemental groupEknee Z or Eknee A ??Knee of heavy elements out of the experimental range
Risulats depend heavily on the interaction model used.
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MACRO EAS-TOPL = p + HeH = Mg + Fe
Macro EAS TOP
Em shower
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4300 m a.s.l. 606 g cm-2
221 counters (15m grid)+ emulsion chambers (80 m2)+ burst detector (80 m2 below EC)
Simulations show that detector is almost blind to heavy fragments
MC assumes knee at E=1.5•1014•Z (below energy range of experiment)
Neural Nets analysis allow to select H or HE events1996-1999 data177 events
Tibet AS experiment
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H SpectrumTibet AS data agree with:RUNJOBKASCADE (Sibyll)
HE Spectrum =“HE+H”-”H”Agree with RUNJOBLower than:JACEE, KASCADE
Conclusion: Composition already heavy at the knee
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Future evolutions from measurements in the 1016 – 1018 eV energy range
If : Ek,Z = Z * Ek,1
SEARCH FOR IRON “KNEE” AT ~ 1017 eV
PRIMARY COMPOSITION
STUDY OF C.R. INTERACTIONS AT UHE TRANSITION GALACTIC – EXTRAGALACTIC C.R.?
KASCADE-GrandeICETOP/ICECUBE
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KASCADE-Grande Experiment @ FZK KarlsruheKASCADE-Grande Experiment @ FZK Karlsruhe
KASCADE
KASCADE e/ detectors Grande array37 Scintillator stations (10 m2 each)Total Surface 0.5 km2
N (> 1018 eV) ~ 250 events(3 y data taking)
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First results from the KASCADE-Grande Experiment
Unfolding analysis from 2 dimensional spectra is possible
All angular bins show the same energy spectrum
Study of systematics still to be improved!!!!!!
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Main Results & Future Developments
1015 eV < E < 1018 eV• Knee observed in the spectra of all EAS components• Knee caused by light elements (don’t forget Tibet AS)
• Primary chemical composition evolves, above the knee, towards heavier elements
• Still differences in the results obtained at different altitudes and with different techniques better understanding of primary interactions!!! (LHC!)
• Anisotropy
• Future Developments: – Search for the “knee” of heavy elements– Detailed study of the 1016 – 1018 eV energy range– Interaction Models (inel, K, ......)