1. Determination of the CR’s light component at energies <100 TeV Beatrice Panico Young Researchers Meeting, Rome 09/02/2010

2. Index Scientific goal ARGO-YBJ experiment Cosmic rays The analisys A simple exercise Conclusions Beatrice Panico

3. The physic Fe COSMIC RAYS H He CNO NeMgSi “ Light Component ” P spectrum – Well known He spectrum - Uncertainties Beatrice Panico

4. The light component Supernova Remnants N49 Grande Nube di Magellano Energy (TeV) J p (E)/J α (E) JACEERUNJOB 101.041.62 1000.791.73 10000.601.86 RUNJOB

5. Beatrice Panico Where they come from? 1.Primary cosmic rays 2.Secondary cosmic rays The cosmic rays

6. Beatrice Panico CR’s spectrum knee 10 6 -10 7 GeV γ is constant at 2.7 ankle 10 9 -10 10 GeV Between the knee and the ankle γ = 3.0 γ raggiunge 3.15

7. Beatrice Panico For each energy … A different method ARGO ~ 5800 m 2 How detect them? EAS array or fluorescence technique >10 3 m 2 10 2 10 4 10 6 10 810 GeV Balloons ~m 2

8. Beatrice Panico ARGO-YBJ

9. Beatrice Panico ARGO-YBJ

10. Beatrice Panico 5800 m 2 154 Cluster 12 RPC10 Pad 8 Strip ARGO-YBJ

11. The method COMPARE THE EXPERIMENTAL DATA WITH THE SIMULATED ONES June 2008 – July 2008 About 15 ∙10 9 Events 1)Determination of the rate measured in YBJ 2)Normalize this value to the atmospheric pressure 3)Selection of events Experimental Data Beatrice Panico

12. Experimental data Determination of the rate measured in YBJ Meteo Data Atmospheric pressure Internal temperature Beatrice Panico

13. Experimental data Determination of the rate measured in YBJ N-tupla Time of the event Number of strips fired after the noise filter The recostructed angle The recostructed core Beatrice Panico YBJ DATA MEDEA++ - Class of strip multiplicity - Class of recostructed angle - Time interval  t=360 s

14. Beatrice Panico Maximum Likelihood Method Eventi hit > 500 Area = 861 m 2 La selezione del core

15. Beatrice Panico StripIndice Strip [100,158] [158,251] [251,398] [398,630] [630,1000] [1000,1500] [1500,2511] [2511,3981] [3981,6301] [6301,10000] [10000,15849] 126 200 316 501 794 1259 1995 3162 5012 7943 12589 Experimental data Determination of the rate measured in YBJ [0°,90°]

16. Beatrice Panico Rate of events for vertical CR (0°-15°) and for each class of multiplicity Experimental data Determination of the rate measured in YBJ

17. Experimental data Integral Rate (2.48 ± 0.03)*N (-1.31 ± 0.01) Beatrice Panico

18. The method COMPARE THE EXPERIMENTAL DATA WITH THE SIMULATED ONES 1)Simulation Code: Corsika (QSJ jet + Fluka) + ArgoG Vers. 1.4 + Medea 2)Simulation of EAS generated by different primaries 3)Determination of effective area 4)Determination of the rate Experimental Data Simulated Data Beatrice Panico

19. RUNJOB J(E)= k E -γ [(m 2 s srGeV) -1 ] JACEE J(E)= k E -γ [(m 2 s srGeV) -1 ] WS J(E)= k E -γ [(m 2 s srGeV) -1 ] Protoni (2.26 ± 0.13) 10 4 E -(2.78±0.05) (2.79 ± 0.77) 10 4 E -(2.80±0.04) (2.35 ± 0.08) 10 4 E -(2.77±0.02) He (1.84 ± 0.14) 10 4 E -(2.81±0.05) (8.85 ± 0.68) 10 3 E -(2.68±0.05) (5.98 ± 0.17) 10 3 E -(2.64±0.02) CNO (3.94 ± 0.55) 10 3 E -(2.70±0.04) (2.20 ± 0.63) 10 2 E -(2.40±0.09) (2.93 ± 0.61) 10 3 E -(2.67±0.02) Fe (0.93 ± 0.08) 10 3 E -(2.57±0.03) (1.36 ± 0.82) 10 2 E -(2.41±0.22) (1.12 ± 0.11) 10 2 E -(2.60±0.09) Simulated data Determination of the effective area

20. Beatrice Panico Wiebel-Sooth et al. Simulated data Determination of the rate

21. Simulated data Composition of showers Beatrice Panico

22. Results 500 Agreement <20% With core selection

23. A simple application Experimental Data (All particle) Experimental Data (only for He) Subtract the p and heavy contributes estimated from model The error of slope is about 1% The error of intercept is about 10% Respect to Wiebel-Sooth the mean difference is 20% For instance if we use Wiebel-Sooth model Beatrice Panico

24. Conclusions 1.The experimental strip multiplicity distribution is in good agreement with the expected one calculated using Wiebel-Sooth et al. composition model 2.Selecting quasi vertical showers with core located on a fiducial area inside the ARGO central carpet, a sample of events mainly induced by proton and helium primaries may be obtained 3.The alfa spectrum may be determined with precision <20% Beatrice Panico 1.1 year of data 2.More corrections 3.Different adronic code