1. TAUP Conference, Sendai 11- 15 September 2007 1 The primary spectrum in the transition region between direct and indirect measurements (10 TeV – 10 PeV) M. Bertaina a,*, G. Battistoni b, S. Muraro b, G. Navarra a, A. Stamerra c a) Universita’ di Torino and INFN Torino, Italy b) Universita’ di Milano and INFN Milano, Italy c) Universita’ di Siena and INFN Pisa, Italy * At present JSPS fellow at RIKEN, Japan

2. 2 The basic question: Based on the experimental data collected so far from ‘direct’ and indirect experiments, is it possible to extract the primary spectrum of the different components? The main request: The proposed solution should be compatible with the majority of the experimental data, if possible, obtained using different techniques and observables, sensitive to different primary particles and characteristics of their cascades in air.

3. 3 The ‘all particle’ spectrum 10TeV10PeV Overlapping region

4. 4 Techniques ‘Direct’ measurements (balloons): Emulsion Chambers (JACEE & RUNJOB) 10 TeV - ~500 TeV Calorimeters (ATIC & CREAM) 50 GeV – 200 TeV Good charge resolution but low statistics Sensitive to the first interaction of the primary particle Indirect measurements (EAS arrays): Electromagnetic component (scintillators) > 100 TeV Muons (tracking detectors, scintillators) > MeV/GeV (surface), TeV (underground) Hadrons (calorimeters) > 500 GeV Cherenkov light (telescopes) > 15 TeV High statistics Energy and composition extracted from comparison with simulations

5. 5 RUNJOB Emulsion chamber on balloon diffuser ( ～ 4cm) target ( ～ 10cm) thin EC( ～ 5c.u.) spacer ( ～ 20cm) A = 0.4 m 2 ; obs time: 1437.5 h, exposure 575 m 2 h

6. 6 Atic-2 20 days Antarctica flight Exp. about 0.3 of RUNJOB BGO calorimeter: 1.15 int New calorimeters ATIC

7. 7 Measurement Techniques of Air Showers

8. 8 Nucl. Instr. Meth. A513 (2003) 490 PROTON PRIMARY PROTON FLUX FROM HADRON FLUX DATA KASCADE CALORIMETER 500 GeV – 1 PeV KASCADE

9. 9 He & CNO (80 – 250 TeV) from Cherenkov light & HE muons: EAS-TOP & MACRO Astrop. Phys., 21 (2004) 223 Proc. 28 th ICRC, 1 (2003) 115 Proc. 29 th ICRC, HE11 (2005) 101 Total exposure 20,000 h m 2 sr x 15 of direct exp.

10. 10 MACRO and EAS-TOP are separated by 1100 - 1300 m of rock corresponding to a threshold E   1.3 - 1.6 TeV. MACRO (as a  detector): - EAS from primaries with E n > 1.3 TeV/n - EAS geometry through the  track (~20 m uncertainty). EAS-TOP (Cherenkov detector): total energy through the amplitude of the detected Cherenkov light signal. Energy uncertainties: 28% stat.+ syst He + CNO

11. 11 KEY POINT OF THE ANALYSIS Beams are well defined: p at E o < 50 TeV p+He at 50 < E o < 100 TeV p+He+CNO at E o > 100 TeV E ≈ 80 TeV N  p ≈ N  He E ≈ 250 Tev N  p ≈ N  He ≈ N  CNO Same efficiency (inside 15%) in TeV  production. Relative abundances are not distorted Primary Energy (TeV) 80 TeV 250 TeV Our simulation agrees with Forti et al., Phys rev. D 42, 3668 (1990) using: E ,th = 1.6 TeV and  = 35 o

12. 12 Cherenkov light: H.E.S.S. Iron: 15 – 150 TeV

13. 13 EAS-TOP KASCADE Ne – N  (GeV) E = 1 - 30 PeV Ne – N  (TeV) E = 1 - 30 PeV

14. 14 KASCADE: energy spectra of single mass groups unfolding Searched: E and A of the Cosmic Ray Particles Given: N e and N  for each single event  solve the inverse problem with y=(N e,N  tr ) and x=(E,A) Measurement: KASCADE array data 900 days; 0-18 o zenith angle 0-91m core distance lg N e > 4.8; lg N  tr > 3.6  685868 events

15. 15 HEMAS:  0 = (5.0±0.1) cm -2 s -1 sr -1 GeV  p -1 A,  p = 2.79±0.04 SIBYLL:  0 = (4.1±0.1) cm -2 s -1 sr -1 GeV  p -1 A,  p = 2.77±0.05 MACRO (E  >1.3 TeV) The most exploited technique in the past (MUTRON, Alkoffer, etc…) The muon spectrum --> All nucleon spectrum MACRO Coll., Phys. Rev. D, Vol. 52 p.3793 (1995) AMANDA (E  >300 GeV) AMANDA Coll., 28 th ICRC, HE 2.1 p.1211 (2003)  0,H = (0.106±0.007) m -2 s -1 sr -1 TeV -1,  H = 2.70±0.02

16. 16 G. Battistoni et al 29th ICRC 6, 309 (2005) The new FLUKA Code

17. 17 L3 and Fluka: agree < 10% S. Muraro, Ph.D. Thesis, 2006 Univ. Milano  FLUKA sim. L3 data Vertical flux L3+Cosmics

18. 18 L3 and Fluka: agree < 10%  FLUKA sim. L3 data Inclined flux (  =53  -58  ) S. Muraro, Ph.D. Thesis, 2006 Univ. Milano

19. 19 Primary Spectrum Example: proton and helium component AMS-BESS fit 2001 Modified NASA spectrum [ G.D.Badhwar and P.M.O'Neill, Adv. Space Res. Vol.17, No. 2 (1996) 7. ] (proton and helium only) to take into account AMS 1998 and BESS data. Include Solar Modulation model  Date dependent S. Muraro

20. 20 Atmospheric muons at mountain altitude We compared FLUKA simulations with the experimental data of atmospheric muons taken at the top of Mt. Norikura, Japan, with the BESS detector. 2770 m above sea level (11.2 GV). The energy range for muons extends up to 100 GeV.

21. 21 BESS 99 @ Mt. Norikura BESS 99 @ Mt. Norikura Phys. Lett. B 564 (2003), 8 – 20 cone of ~11 o -- Geomagnetic Cut-off: 11.2 GV ++ 2,700 m asl Looks better at higher energies S. Muraro  FLUKA sim. BESS data

22. 22 All particle spectrum  ~2.6

23. 23 The Proton Spectrum Nice agreement among all techniques  p ~2.7

24. 24 The Helium Spectrum Some discrepancies, but high He flux is preferred  He ~2.55

25. 25 The CNO spectrum At PeV energies the spectrum is divided only in 3-5 mass groups, therefore, fluxes might be slightly overestimated. Direct measurements report often C+O  CNO ~2.55

26. 26 The Iron Spectrum CAUTION: the definition of Fe group depends on the experiment  Fe ~2.55  Fe ~2.65

27. 27 A plausible answer from the data….  =2.65