Look inside the boraxino detector. Credit: Boraxino Collaboration
Neutrinos Yield First Experimental Proof of Catalyzed Fusion Dominance in Many Stars
An international team of 100 Boraxino collaborators, including particle physicist Andrea Poker from Amherst University in Massachusetts, reports Nature This week we are looking for neutrinos directly from the Sun, which is the first time that our Sun has a carbon-nitrogen-oxygen (CNO) fusion cycle.
Pokar explains that the CNO cycle is an impressive source of energy that powers stars heavier than the Sun, but has never been able to find one directly in any star, Pokar explains.
For most of their lives, stars combine hydrogen with helium to obtain energy, he adds. In stars like our Sun or lighter, this is mostly caused by ‘proton-proton’ chains. However, many stars are heavier and hotter than our Sun, and their composition contains heavier elements than helium, known as quality metallurgy. The 1930s prediction that the CNO-cycle would be predominant in heavy stars.
The neutrinos emitted as part of these processes provide scientific signatures that can distinguish scientists from the ‘CNO-cycle’ to the ‘proton-proton chain’. The shout points out, “The confirmation of CNO burning in our sun, where it works at only one percent, strengthens our confidence that we understand how the stars work.”
The boraxino detector is located deep in the foothills of the Pennina in central Italy at INFN’s laboratory Nazionale del Gran Sasso. When neutrinos collide with electrons in a 300 ton ultra-pure organic scintillator, they detect neutrinos as the light emitted. Credit: Boraxino Collaboration
In addition, CNO neutrinos can help solve important open questions of stellar physics, he adds. That is, how the Sun’s central metal, just from the core, can be determined by the CNO neutrino rate, is related to the metal elsewhere in the star. Conventional models have run into trouble – the solution of the surface metal by spectroscopy, the different method, does not agree with the measurements of the sub-surface metal inferred from the observations of heliosisology g.
Poker says the neutrino is actually the only direct probe that contains the main body of stars, including the Sun, but it is very difficult to measure. About 420 billion of them hit every square inch of the Earth’s surface every second, though almost all of them pass without communication. Scientists can only detect them using very large detectors with exceptionally low background radiation levels.
The boraxino detector is deep at the bottom of the mountain of En Penina in central Italy at INFN’s laboratory Nazionale del Gran Sasso. When neutrinos collide with electrons in a 300 ton ultra-pure organic scintillator, they detect neutrinos as the light emitted. Its great depth, size and precision make boraxino a unique detector for this type of science, with low-background radiation in its class alone, says Poker. The project was started in the early 1990s by a group of physicists at the University of Milan led by Gianpaio Bellini, Frank Laprais in Princeton and Raju Raghavan at the end of Bell Labs.
Until its latest investigation, components of the ‘proton-proton’ solar neutrino flux were successfully measured in collaboration with Boraxino, helped improve the neutrino flavor-c silage parameters and, most effectively, also measured the first step of the cycle: very low power pp. ‘ Neutrinos, Poker recalls.
His researchers dreamed of expanding the field of science to look at CNO neutrinos – especially in the low-background narrow descriptive field, but the prize seemed out of reach. However, research groups at Princeton, Virginia Tech and Yumas Amherst believe that CNO neutrinos can evolve to detect excellent detector stability using even more refining steps and methods.
Thanks to a series of moves over the years and to identify and stabilize in the background, U.S. scientists and full collaboration have been successful. “In addition to showing CNO neutrinos which is the topic of this week Nature The article is now likely to help solve the metal problem, ”says Pokar.
Prior to the discovery of CNO Neutrinos, Labore had scheduled Boraxino to be operational by 2020. But, the data used in the analysis Nature Scientists have continued to collect data as central purity has improved, creating a new result on the metal, which is a real possibility, Poker says. Data collection could expand until 2021 because logistics and permitting requirements, while ongoing, are negligible and time consuming. “Every extra day helps,” he comments.
Ponker has been with the project since his undergraduate school days at Princeton in a group led by Frank Capraprice, where he worked on a nylon shipbuilding, construction and fluid handling system. He later worked with his students at UMS Amherst on data analysis and, more recently, techniques to characterize the background for CNO neutrino measurements.
Reference: Boraxino Collaboration, 25 November 2020 “Experimental Evidence of Neutrinos Produced in the CNO Fusion Cycle in the Sun” Nature.
DOI: 10.1038 / s41586-020-2934-0
The work was supported in the US by the National Science Foundation. Boraxino is an international collaboration funded by the Nuclear Physics Institute (INFN) for the Italian national organization, and also by funding agencies from Germany, Russia and Poland.
