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| Author(s): |
Luiz Augusto Stuani Pereira
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Instituto de Física Gleb Wataghin |
| Defense date: | 2018-09-19 |
| Examining board members: |
Anderson Campos Fauth;
Carola Dobrigkeit Chinellato;
Edmilson José Tonelli Manganote;
Hélio Nogima;
Marcelo Augusto Leigui de Oliveira
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| Advisor: | Anderson Campos Fauth |
| Abstract | |
In the search for understanding the formation and development of the Universe, the cosmic ray detection plays a key role. Especially at ultra-high energies, its origin is scarcely known. The detection of ultra high energy cosmic rays may reveal a still unknown nature of forces in the Universe. Higher energy muons can provide information about the processes involved in the development of extensive air showers. Since this component is coupled with the hadronic component, it immediately provides crucial information about the properties of the primary cosmic rays. Thus, muons can be used to study the chemical composition of primary particles as their multiplicity depends on the atomic number of the primary particle. In this thesis, the feasibility of cosmic ray mass composition measurements is studied using the hybrid detector array with surface detectors (SD), muon detectors (MD), fluorescence detectors (FD) and radio detectors (RD) of the Pierre Auger Observatory. A detailed study of the mass discrimination power for simulated showers induced by proton and iron is presented using the muon density reconstructed at different distances from the shower axis (300 - 1000 m). The mass separation power is analysed by combining the reconstructed muon density with the SD energy (primary energy measured with the surface detectors), the RD energy (radiation energy emitted by the electromagnetic component of the air shower which is detected by radio antennas) and the FD energy (fluorescence energy emitted by atmospheric nitrogen molecules). These analyses are performed to investigate which distance from the shower axis and which energy estimator gives the best mass separation. As a result, the ratio between the muon density reconstructed at 500 m and the FD energy features the best mass separation for proton and iron-induced showers. Moreover, the combined muon density with different energy estimators achieves a higher mass separation than Xmax and it increases with increasing primary energy. Finally, the measurement of the mass sensitive observables derived from the combined analysis of the muon signal with different energy estimators shows a composition compatible with the measurements of the Xmax for the spectrum region where the transition from Galactic to extragalactic cosmic ray occurs (AU) | |
| FAPESP's process: | 13/23074-0 - Muons in high energy cosmic ray air showers |
| Grantee: | Luiz Augusto Stuani Pereira |
| Support Opportunities: | Scholarships in Brazil - Doctorate |