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Experimental Seminars in Particle Physics
Borexino and the first direct detection of CNO neutrinos.
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Europe/Zurich
Description
Stars are fueled by nuclear reactions occurring in their core, belonging to the so-called proton-proton chain and the CNO cycle. In massive stars (approximately 1.3 more massive than our Sun) the CNO cycle is dominant, while in lighter stars (including our Sun) the proton-proton chain prevails.
Borexino has been taking data for over 13 years under the Gran Sasso mountain with the goal of detecting neutrinos emitted in the nuclear reactions occuring in the core of our Sun.
Neutrinos are elusive particles and in this seminar I will discuss the details of how it is possible to detect them and even distinguish from which reaction they come from. During its long life Borexino has succeded to directly measure solar neutrinos from all the reactions belonging to the proton-proton chain in the Sun. Recently, Borexino has also announced the first observation of neutrinos emitted by the CNO reactions in the Sun’s core: this is a breakthrough in astrophysics, since it provides the first direct experimental evidence of the most important mechanism of energy production in the Universe.
The story of how we were able to measure the faint CNO signal coming from our Star by keeping as stable as possible the temperature of our detector is an interesting one and I will try to tell it underlining the main issues and obstacles we had to overcome.
