Status of Cosmic Rays Physics at the Knee Andrea Chiavassa Università and INFN Torino NOW 2006 Otranto 9-16 September 2006

1 particle m -2 s -1 Knee 1 particle m -2 year -1 Ankle 1 particle km -2 year -1

Hypotesis on the origin of the Knee Reach of maximum energy at the acceleration in Galactic Sources? SNR  (E knee  Z) Cannonball  (E knee  A) Diffusion: Escape of particles from Galactic Magnetic fields? (E knee  Z) Unknown effects of interaction in the development of Extensive Air Showers? (E knee  A)

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 

ExperimentX (g cm -2 ) CASA-MIA BLANCA 870 Scintillators Ne N  Cerenkov Light X max HEGRA790Scintillators Ne Cerenkov Light N  X max EAS-TOP810Scintillators Ne Streamer Tubes N  >1 GeV  N h Cerenkov Light N  KASCADE1020 Scintillators Ne N  (E  >230 MeV) Calorimetr N h E h MWPC N  (E  >2400 MeV) TIBET AS  606Scintillators Ne Emulsion  -families TUNKA 25950Cerenkov Light N  X max

The spectra of all the components of EAS show the “Knee”: Ne, N ,  E h KASCADE EAS-TOP NN Ne EhEh

Spectra of “light” and “heavy” elements of Cosmic Rays KASCADE Only the spectrum obtained using “electron rich” events shows the change of slope

Energy Spectrum of Single Elements

Spectra of light elements show the knee Position of the knee vary with primary elemental group E knee  Z or E knee  A ?? Knee of heavy elements out of the experimental range Risulats depend heavily on the interaction model used.

MACRO EAS-TOP L = p + He H = Mg + Fe Macro EAS TOP Em shower

4300 m a.s.l. 606 g cm counters (15m grid) + emulsion chambers (80 m 2 ) + burst detector (80 m 2 below EC) Simulations show that detector is almost blind to heavy fragments MC assumes knee at E= Z (below energy range of experiment) Neural Nets analysis allow to select H or HE events data 177 events Tibet AS  experiment

H Spectrum Tibet AS  data agree with: RUNJOB KASCADE (Sibyll) HE Spectrum =“HE+H”-”H” Agree with RUNJOB Lower than:JACEE, KASCADE Conclusion: Composition already heavy at the knee

Future evolutions from measurements in the – eV energy range If : E k,Z = Z * E k,1 SEARCH FOR IRON “KNEE” AT ~ eV PRIMARY COMPOSITION STUDY OF C.R. INTERACTIONS AT UHE TRANSITION GALACTIC – EXTRAGALACTIC C.R.? KASCADE-Grande ICETOP/ICECUBE

KASCADE-Grande FZK Karlsruhe KASCADE KASCADE e/  detectorsGrande array 37 Scintillator stations (10 m 2 each) Total Surface 0.5 km 2 N (> eV) ~ 250 events (3 y data taking)

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!!!!!!

Main Results & Future Developments eV < E < 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 – eV energy range –Interaction Models (  inel, K, ......)