Transcript Slide 1
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 (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) 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 Experiment X (g cm-2) CASA-MIA BLANCA 870 Scintillators Ne Nm Cerenkov Light Xmax HEGRA 790 Scintillators Ne Cerenkov Light Ng Xmax EAS-TOP 810 Scintillators Ne Streamer Tubes Nm (Em>1 GeV) Nh Cerenkov Light Ng KASCADE 1020 Scintillators Ne Nm (Em>230 MeV) Calorimetr Nh Eh MWPC Nm (Em>2400 MeV) TIBET ASg 606 Scintillators Ne Emulsion g-families TUNKA 25 950 Cerenkov Light Ng Xmax The spectra of all the components of EAS show the “Knee”: Ne, Nm, SEh KASCADE SEh Nm Ne EAS-TOP 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 Eknee Z or Eknee 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 Em shower Macro EAS TOP Tibet ASg experiment 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 events 1996-1999 data 177 events H Spectrum Tibet ASg 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 1016 – 1018 eV energy range KASCADE-Grande ICETOP/ICECUBE 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-Grande Experiment @ FZK Karlsruhe KASCADE N (> 1018 eV) ~ 250 events (3 y data taking) KASCADE e/g + m detectors Grande array 37 Scintillator stations (10 m2 each) Total Surface 0.5 km2 First results from the KASCADE-Grande Experiment Study of systematics still to be improved!!!!!! All angular bins show the same energy spectrum Unfolding analysis from 2 dimensional spectra is possible 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 ASg) • 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 (sinel, K, m......)