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Determination of the CR’s light component at energies <100 TeV Beatrice Panico Young Researchers Meeting, Rome 09/02/2010
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Index Scientific goal ARGO-YBJ experiment Cosmic rays The analisys A simple exercise Conclusions Beatrice Panico
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The physic Fe COSMIC RAYS H He CNO NeMgSi “ Light Component ” P spectrum – Well known He spectrum - Uncertainties Beatrice Panico
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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
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Beatrice Panico Where they come from? 1.Primary cosmic rays 2.Secondary cosmic rays The cosmic rays
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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
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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
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Beatrice Panico ARGO-YBJ
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Beatrice Panico ARGO-YBJ
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Beatrice Panico 5800 m 2 154 Cluster 12 RPC10 Pad 8 Strip ARGO-YBJ
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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
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Experimental data Determination of the rate measured in YBJ Meteo Data Atmospheric pressure Internal temperature Beatrice Panico
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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
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Beatrice Panico Maximum Likelihood Method Eventi hit > 500 Area = 861 m 2 La selezione del core
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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°]
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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
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Experimental data Integral Rate (2.48 ± 0.03)*N (-1.31 ± 0.01) Beatrice Panico
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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
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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
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Beatrice Panico Wiebel-Sooth et al. Simulated data Determination of the rate
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Simulated data Composition of showers Beatrice Panico
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Results 500 Agreement <20% With core selection
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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
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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
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