Determination of the CR’s light component at energies <100 TeV

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

4. The light component Supernova Remnants N49 Grande Nube di Magellano RUNJOB Beatrice Panico

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

6. CR’s spectrum knee 106-107 GeV γ is constant at2.7 ankle109-1010 GeV Between the knee and the ankle γ=3.0 γ raggiunge 3.15 Beatrice Panico

7. 102 104 106 108 1010 GeV How detect them? For each energy … A different method Balloons ~m2 ARGO ~ 5800 m2 EAS array or fluorescence technique >103 m2 Beatrice Panico

8. ARGO-YBJ Beatrice Panico

9. ARGO-YBJ 5800 m2 12 RPC 10 Pad 8 Strip 154 Cluster Beatrice Panico

10. The method COMPARE THE EXPERIMENTAL DATA WITH THE SIMULATED ONES Experimental Data • Determination of the rate measured in YBJ • Normalize this value to the atmospheric pressure • Selection of events June 2008 – July 2008 About 15 ∙109 Events Beatrice Panico

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

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

13. La selezione del core Maximum Likelihood Method Eventi hit > 500 Area = 861 m2 Beatrice Panico

14. Experimental data Determination of the rate measured in YBJ [0°,90°] Beatrice Panico

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

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

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

18. Simulated data Determination of the effective area Beatrice Panico

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

20. Simulated data Composition of showers Beatrice Panico

21. Results 500 With core selection Agreement <20% Beatrice Panico

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

23. Conclusions • The experimental strip multiplicity distribution is in good agreement with the expected one calculated using Wiebel-Sooth et al. composition model • 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 • The alfa spectrum may be determined with precision <20% • 1 year of data • More corrections • Different adronic code Beatrice Panico