Measurement of the proton air cross section using hybrid data of the Pierre Auger Observatory [Elektronische Ressource] / von Ralf Matthias Ulrich

Measurementoftheproton-aircrosssectionusinghybriddataofthePierreAugerObservatoryZurErlangungdesakademischenGradeseinesDOKTORSDERNATURWISSENSCHAFTENvonderFakulta¨tfu¨rPhysikderUniversita¨t(TH)KarlsruhegenehmigteDISSERTATIONvonDipl.-Phys. RalfMatthiasUlrichausBasel(Schweiz)Tagdermu¨ndlichenPru¨fung: 21.12.2007Referent: Prof. J.Blu¨merKorreferent: Prof. G.QuastALT XEAbstractThe subject of this thesis is the measurement of the proton-air cross section at ultra highenergy with hybrid data of the Pierre Auger Observatory. Based on a critical review of theshortcomings of previous air shower measurements, a new analysis method is developed.Thisanalysis methodtakesintoaccount themostimportantandrelevantexperimentalandair shower physics effects. The impact of a changed cross section extrapolation on the re-sulting air shower development is considered in addition to its more obvious effect on thedistributionofshowerstartingpoints. Furthermore,detectoracceptanceeffectsareexplicitlyincludedinthereconstructionansatz,whichallowsustousealmostthecompletedatasetintheanalysis. Systematicuncertaintiesontheresultingcrosssectionsarethoroughlystudiedand quantified. Assuming a proton dominated composition, the analysis is applied to hy-briddataofthePierreAugerObservatory. Theobtainedcrosssectionis,withinthestatisticalandsystematicuncertainties,inagreementwithpredictionsfromhadronicinteractionmod-18.4elsupto10 eV.Athigherenergiestheresultingcrosssectionincreasesrapidly.