They reproduce at CERN a key reaction in the evolution of the galaxy and solar system.
A team led by the Institute of Corpuscular Physics (St.IFIC), mixed center CSIC and the University of Valencia, managed to recreate in the laboratory CERN key nuclear reaction in Switzerland understand the origin and evolution of our galaxy and solar system.
In a work published in Physical Review Letters details how lead-204 is formed, an isotope that explains evolution of the chemical composition of our galaxy since the formation of the first starsabout twelve billion years ago. The production of this isotope in red giant stars also allows us to date the first solid materials created in the Solar System and is used to determine their age.
The amount of lead-204 (Pb204) produced in red giant stars has not yet been accurately quantified. due to ignorance of the nuclear reaction occurring in the isotope of the chemical element preceding itThallium-204 (Tl204). This isotope is radioactive and lasts an average of 3.78 years before decaying. Therefore, it is extremely difficult to produce a sample of this material for experiments.
Reaction of a neutron beam to an isotope
Now a research team from IFIC and the Polytechnic University of Catalonia (UPC), thanks to collaboration with the Paul-Scherrer Institute in Switzerland and with high flow reactor from Grenoble at the Institut Laue-Langevin in France, managed to produce a sample of thallium-204 large enough to work with it at the n_TOF neutron experiments laboratory at CERN, located in Geneva (Switzerland).
After synthesizing and characterizing this sample, the research team first measured the reaction of a neutron beam to this isotope. They then ran calculations with astrophysics experts as part of NuGrid, an international collaboration that develops tools for large-scale simulations of nucleosynthesis with applications in nuclear physics.
The results made it possible for the first time to accurately determine the amount of lead-204 produced in AGB red giant stars. Stars of this type play a fundamental role in evolution of the chemical composition of elements present in our galaxy and solar system and is responsible for the creation of half of the elements heavier than iron existing in nature. The life cycle of these stars constantly contributes chemical enrichment galaxies in the Universe.
Meteorites with the chemical composition of the Solar System
“The result shows excellent agreement with lead-204 measured in Iwuna-type carbonaceous chondrites (CI), meteorites that preserve the chemistry of the solar system,” he explains. Caesar DomingoCSIC researcher leading research at IFIC. “There would be no need to resort to alternative hypotheses for Pb204 nucleosynthesis, such as supernovae or possible fractionation mechanisms that may have occurred in the early Solar System,” he points out.
“While this experiment represents significant progress, we need new revolutionary ideas to be able to access many more nuclei of great interest like this one in the laboratory, but which are found in explosive stellar environments such as supernovae or binary neutrons.” star systems.” , the researcher concludes.
Link:
Casanovas-Hoste et al. (n_TOF Collaboration). “Shedding light on the origin of 204Pb, the heaviest isotope available only from Solar System processes.” Physics Rev. Lett..