The Institute of Corpuscular Physics (IFIC), at the UV Science Park, is leading an experiment that sheds new light on the formation of chemical elements such as zirconium or molybdenum, with important industrial applications. New measurements show that these elements could be formed in extreme phenomena of the cosmos up to 70% higher than previously thought
An international team led by the Institute of Corpuscular Physics (IFIC), which is located in the scientific-academic area of the Science Park of the University of Valencia, as well as being a joint center of the CSIC and the University of Valencia, has achieved a milestone in the exploration of the origin of matter in the universe. For the first time, this team has measured the decay properties of 37 extremely rare and fleeting atomic nuclei, which exist only for fractions of a second and are not naturally found on Earth. The work, published in the prestigious journal Physical Review Letters, provides new information to decipher one of the great enigmas of modern physics: How are heavier elements than iron formed?
The answer to this puzzle points to extreme phenomena such as neutron star fusion, and the new work of IFIC provides crucial data for developing models that describe this process. The 37 atomic nuclei studied are located in an unexplored region near nickel-78, a key element for understanding the structure of heavy atomic nuclei. The lightest elements in the universe, such as hydrogen and helium, formed just after the Big Bang. But the heavier elements such as silver, gold or uranium did so in much more extreme scenarios like supernova explosions or neutron star fusing.
The universe as a great factory of elements
These phenomena are very difficult to detect and study experimentally. A turning point came in 2017, when the LIGO and VIRGO experiments first detected gravitational waves resulting from a fusion of two neutron stars, which generate explosions called kilonovas. As they directed their telescopes to the region of sky indicated, the astronomers observed a light signal whose behaviour was in line with the theory: the radioactive decay of newly formed heavy elements fed that light. Subsequent analyses identified elements such as strontium, yttrium and zirconium. For the first time, the synthesis of heavy elements in a cosmic event was observed 'live'.
The problem is that many of the atomic nuclei involved in these processes do not exist stably on Earth and last only a fraction of a second, so they have never been able to study... so far. The international scientific team led by IFIC’s Gamma and Neutron Spectroscopy Group has made a significant breakthrough: it has been able to measure, for the first time, fundamental properties of 37 very exotic atomic nuclei, which make it possible to predict more precisely how heavier elements than iron such as yttrium, zirconium, niobium or molybdenum are formed, with important industrial applications.
"The evolution of the abundance of chemical elements in the universe is indeed complex, with a variety of processes contributing to the end result. Combining astronomical observations, nuclear physics experiments and astrophysical models we are closer to solving the puzzle", José Luis Taín, IFIC researcher leading the experiment
The finding combines the production capacity of exotic nuclei from the RIKEN-Centre’s Radioactive Beam FacilityNishina, in Japan, with the high efficiency of a neutron detector developed by the IFIC research group and the Polytechnic University of Catalunya. Other teams from the Technical University of Darmstadt (Germany) and the University of Valencia collaborate in nucleosynthesis calculations, element formation.
Production of up to 70% more elements than previously thought
The results of the work, recently published in Physical Review Letters, show that the process of synthesis and dispersion of heavy elements, powered by neutrino wind, produces the nuclei measured in this work and occurs in the short time before the system collapses into a black hole. The use of new nuclear data shows a significant increase in the production of the elements identified in the 2017 event compared to previous estimates. The new measurements show that these elements could be formed in a greater quantity than previously thought, about 50% to 70% more than thought.
Álvaro Tolosa Delgado, first author of the paper and currently a CERN researcher, comments that "there was a previous opinion that the properties of the nuclei we studied would have little impact on abundances. This is contradicted by our work, which points to the need to extend such measures to other nuclei". For his part, José Luis Taín, IFIC researcher who leads the experiment, points out: "the evolution of the abundance of chemical elements in the universe is really complex, with a variety of processes contributing to the final result. Combining astronomical observations, nuclear physics experiments and astrophysical models brings us closer to solving the puzzle".
Source: Delegation CSIC Comunitat Valenciana
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