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T: Fachverband Teilchenphysik
T 28: Kosmische Strahlung 1
T 28.6: Talk
Monday, March 24, 2014, 18:05–18:20, P5
Sensitivity of the correlation between the depth of shower maximum and the signal in ground stations to the cosmic ray composition — •Alexey Yushkov and Markus Risse for the Pierre Auger collaboration — University of Siegen, Siegen, Germany
Determination of the mass composition of ultra-high energy cosmic rays is a priority objective for the running extensive air shower (EAS) experiments. Results on the primary composition based on analysis of mass sensitive characteristics of EAS, like depth of the shower maximum Xmax or signal in ground stations S, strongly depend on the choice of hadronic interaction models and are affected by experimental systematic errors. In this paper we investigate what can be learned from the statistical correlation factor r between the depth of shower maximum and the signal in water Cherenkov tanks, when these observables are measured simultaneously with fluorescence and surface detectors. We use a ranking (non-parametric) correlation coefficient r that is independent of systematic uncertainties of the absolute scales of both S and Xmax. For realistic detector simulations we find that r can provide a robust statistically significant measure of the spread of masses in the primary beam irrespectively of the hadronic interaction model used. The conclusions on the purity of the primary beam can serve for cross-checks with the results on mass composition obtained with other techniques and for testing of astrophysical scenarios.
Gefördert durch die BMBF-Verbundforschung Astroteilchenphysik.