This title appears in the Scientific Report :
2021
Looking inside the Sun with the Borexino experiment: detection of solar neutrinos from the proton-proton chain and the CNO cycle
Looking inside the Sun with the Borexino experiment: detection of solar neutrinos from the proton-proton chain and the CNO cycle
The Sun is fueled by fusion processes occurring in its core that convert hydrogen into helium. Photons produced in these reactions take an order of billion years to reach the surface. However, there is another byproduct of nuclear fusion: neutrinos. They are light and electrically neutral, and, unli...
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Personal Name(s): | Redchuk, Mariia (Corresponding author) |
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Ludhova, Livia (Thesis advisor) / Stahl, Achim | |
Contributing Institute: |
Experimentelle Hadrondynamik; IKP-2 |
Imprint: |
2020
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Physical Description: |
214 |
Dissertation Note: |
Dissertation, RWTH Aachen, 2020 |
Document Type: |
Dissertation / PhD Thesis |
Research Program: |
Cosmic Matter in the Laboratory |
Publikationsportal JuSER |
The Sun is fueled by fusion processes occurring in its core that convert hydrogen into helium. Photons produced in these reactions take an order of billion years to reach the surface. However, there is another byproduct of nuclear fusion: neutrinos. They are light and electrically neutral, and, unlike photons, escape the Sun in a matter of seconds. These so-called solar neutrinos are the only carriers of real-time information about the core of our Star. We know that at least 99% of solar energy is generated through the proton-proton (pp) fusion chain. One more process through which hydrogen-to-helium fusion may occur is the catalytic carbon-nitrogen-oxygen (CNO) cycle. As it is hypothesized to be the main source of energy in heavier stars, its discovery would carry implications in astrophysics, and provide insights about the chemical composition of the core of the Sun, which is not yet fully understood. Moreover, we can exploit this intense natural beam of neutrinos radiated by the Sun to study the phenomenon of neutrino oscillation, the discovery of which was achieved thanks to solar neutrino data. The Borexino detector was designed with the primary goal of detecting the so-called $^7$Be neutrinos, originating from the pp chain. It is particularly suitable for solar neutrino measurement due to its unprecedented radiopurity and resolution at low energies. After ten years of data taking, the Borexino experiment has comprehensively studied all pp-chain neutrinos, not only fulfilling but even surpassing its purpose. This thesis presents the results and implications of this measurement, as well as the analysis behind it. The next milestone of Borexino was to probe the existence of the CNO cycle in the Sun through the detection of neutrinos produced in it. I will describe my work on the methods of monitoring the evolution of the detector and improving the quality of its data, which was deemed crucial for the CNO neutrino analysis. Concluding my thesis, I will present the analysis methods and preliminary results, which show evidence of the existence of CNO neutrinos. The work described in this thesis and my accomplishments are achieved thanks to the collective effort of the Borexino collaboration. |