Progress towards a cross-callibration of the Auger and Telescope Array Fluorescence telescope via an air-borne light source

THE PIERRE AUGER COLLABORATION.; S. J. SCIUTTO

Conferencia; 33rd International Cosmic Ray Conference; 2013

The composition of cosmic rays at the highest energies is one of the most important problems inUHE cosmic ray physics. Recent results using fluorescence and hybrid fluorescence/surface array detectors(HiRes/Telescope Array/Auger) appear to lead to inconsistent conclusions. Comparison is not straightforwardbecause of different acceptance and resolution of the various experiments. Here we take a 4-component mixtureof protons, helium, nitrogen, and iron that varies with energy in such a way that it reproduces the Auger Xmaxdata (Auger Xmax data as obtained with hybrid measurements). We use this mix to simulate air showers in the TAaperture. These events are then passed through the TA detector simulation and reconstructed using TA hybridmethods and cuts. In this paper we describe the method and present the results of the simulations. The results showthat the hXmaxi for the Auger mix composition would be observed by TA hybrid (after full event reconstruction)with a bias of 5:20:4 g/cm2, and the pure proton coposition will be observe with a bias of 11:50:9 g/cm2.The difference in the expected hXmaxi (reconstructed by TA-hybrid) between the pure proton and the Auger mixcompositions is 20 g/cm2 at 1019 eV, and the present study shows that, given the number of events generated, theTelescope Array would be able to distinguish between these two compositions with a confidence level better than4 sigmas.