Electromagnetic shower measurements with the upgraded Pierre Auger Observatory
IDPASC Portugal - PHD Programme 2017
2017 / 2018
Instituto Superior Técnico
Laboratório de Instrumentação e Física Experimental de Partículas
The Pierre Auger Observatory is the largest hybrid detector for the highest energy cosmic rays, above 1 EeV. The particle showers created by interactions in the atmosphere are imaged by fluorescence telescopes and sampled in an array of ground detectors covering 3000 km2, in Argentina. The telescopes measure the excitation of atmospheric molecules by electrons and photons, while the current surface detectors have also added sensitivity to muons. The combined interpretation of the results indicates there is a problem in the shower simulation models, based on extrapolation of the particle interactions as measured in accelerators at lower energies. The Observatory is being upgraded with new detectors, to measure separately the electromagnetic and the muonic shower components at ground. In a small part of the array, RPCs (developed by LIP) will be installed under the existing stations, to isolate the muons. On the other hand, scintillator detectors – less sensitive to muons – will be placed above all the stations of the array. Scintillators are used as the sole ground detector type in Telescope Array (TA), a similar observatory operating in the northern hemisphere. Even before the installation of the new detectors, statistical separation of these two components can be attempted by analysing their different average patterns at ground. This can be a first step for preparing the adaptation of the existing event reconstruction tools for a stand-alone analysis of the electromagnetic component from the new scintillator detectors data. Having an analysis chain which is independent of the full Auger surface detector reconstruction – and more similar to that of TA – will be a very important step to cross-check and validate the component separation of individual showers, which is the main goal of the full Auger upgrade.