The Borexino cooperation, in which likewise researchers from TU Dresden are included, has actually prospered after more than 80 years in experimentally verifying the Bethe-Weizsäcker cycle.
Stars produce their energy through nuclear combination by transforming hydrogen into helium — a procedure understood to scientists as “hydrogen burning.” There are 2 methods of performing this combination response: on the one hand, the so-called pp cycle (proton-proton response) and the Bethe Weizsäcker cycle (likewise called the CNO cycle, stemmed from the components carbon (C), nitrogen (N) and oxygen (O)) on the other hand.
The pp cycle is the primary energy source in our Sun, just about 1.6 per mil of its energy originates from the CNO cycle. However, the Standard Solar Model (SSM) anticipates that the CNO cycle is most likely the primary response in much bigger stars. As early as the 1930s, the cycle was in theory anticipated by the physicists Hans Bethe and Carl Friedrich von Weizsäcker and consequently called after these 2 gentlemen. While the pp cycle might currently be experimentally shown in 1992 at the GALLEX experiment, likewise in the Gran Sasso massif, the speculative evidence of the CNO cycle has up until now not achieved success.
Both the pp cycle and the CNO cycle produce many neutrinos — extremely light and electrically neutral primary particles. The reality that neutrinos barely engage with other matter permits them to leave the interior of the sun at nearly the speed of light and to carry the details about their origin to earth unrestricted. Here the ghost particles run out than to be caught. This is a rather complicated endeavor, which is just possible in a couple of massive experiments worldwide, considering that neutrinos appear as little flashes of light in a big tank filled with a mix of water, mineral oil, and other compounds, likewise called scintillator. The assessment of the determined information is complicated and looks like searching for a needle in a haystack.
Compared to all previous and continuous solar neutrino experiments, Borexino is the very first and just experiment worldwide that has the ability to determine these various elements separately, in genuine time and with a high analytical power. This week, the Borexino research study cooperation had the ability to reveal an excellent success: In the popular clinical journal Nature, they provide their outcomes on the very first speculative detection of CNO neutrinos — a turning point in neutrino research study.
Dresden physicist Professor Kai Zuber is an enthusiastic neutrino hunter.
He is associated with various experiments worldwide, such as the SNO cooperation in Canada, which was granted the Nobel Prize for its discovery of a neutrino mass. The reality that with Borexino, he and his coworkers Dr. Mikko Meyer and Jan Thurn have actually now prospered in experimentally showing the CNO neutrinos for the very first time is another significant turning point in Zuber’s clinical profession: “Actually, I have now achieved everything I had imagined and hoped for. I (almost) no longer believe in great new discoveries in solar neutrino research for the rest of my lifetime. However, I would like to continue working on the optimization of the experiments, in which the Felsenkeller accelerator here in Dresden plays an extremely important role. For sure, we will be able to have even more precise measurements of the Sun in the future.”
Read Neutrinos Yield First Experimental Evidence of the CNO Energy-Production Mechanism of the Universe for more on this research study.
Reference: “Experimental evidence of neutrinos produced in the CNO fusion cycle in the Sun” by The Borexino Collaboration, 25 November 2020, Nature.