| Title | Weighing in on the Origin of Heavy Elements | |
| Date | Saturday April 04 2020, @08:39AM | |
| Author | martyb | |
| Topic | ||
| from the Absolutely-smashing-discovery! dept. | ||
Arthur T Knackerbracket has found the following story:
A long-held mystery in the field of nuclear physics is why the universe is composed of the specific materials we see around us. In other words, why is it made of "this" stuff and not other stuff?
Specifically of interest are the physical processes responsible for producing heavy elements -- like gold, platinum and uranium -- that are thought to happen during neutron star mergers and explosive stellar events.
Scientists from the U.S. Department of Energy's (DOE) Argonne National Laboratory led an international nuclear physics experiment conducted at CERN, the European Organization for Nuclear Research, that utilizes novel techniques developed at Argonne to study the nature and origin of heavy elements in the universe. The study may provide critical insights into the processes that work together to create the exotic nuclei, and it will inform models of stellar events and the early universe.
[...] The nuclear physicists in the collaboration are the first to observe the neutron-shell structure of a nucleus with fewer protons than lead and more than 126 neutrons -- "magic numbers" in the field of nuclear physics.
At these magic numbers, of which 8, 20, 28, 50 and 126 are canonical values, nuclei have enhanced stability, much as the noble gases do with closed electron shells. Nuclei with neutrons above the magic number of 126 are largely unexplored because they are difficult to produce. Knowledge of their behavior is crucial for understanding the rapid neutron-capture process, or r-process, that produces many of the heavy elements in the universe.
[...] This experiment focused on the mercury isotope 207Hg. The study of 207Hg could shed light on the properties of its close neighbors, nuclei directly involved in key aspects of the r-process.
"One of the biggest questions of this century has been how the elements formed at the beginning of the universe," said Argonne physicist Ben Kay, the lead scientist on the study. "It's difficult to research because we can't just go dig up a supernova out of the earth, so we have to create these extreme environments and study the reactions that occur in them."
[...] The first analyses of the data from the CERN experiment confirm the theoretical predictions of current nuclear models, and the team plans to study other nuclei in the region of 207Hg using these new capabilities, giving deeper insights into the unknown regions of nuclear physics and the r-process.
Journal Reference:
T. L. Tang, B. P. Kay, C. R. Hoffman, et al. First Exploration of Neutron Shell Structure below Lead and beyond N=126. Physical Review Letters, 2020; 124 (6) DOI: 10.1103/PhysRevLett.124.062502
-- submitted from IRC
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