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posted by Fnord666 on Tuesday March 10 2020, @07:10AM   Printer-friendly
from the I-thought-it-was-seven dept.

Argonne's pioneering user facility to add magic number factory:

One of the big questions in physics and chemistry is, how were the heavy elements from iron to uranium created? The Argonne Tandem Linac Accelerator System (ATLAS) at the U.S. Department of Energy's (DOE) Argonne National Laboratory is being upgraded with new capabilities to help find the answer to that question and many others.

[...] Since its inception, ATLAS has brought together the world's leading scientists and engineers to solve some of the most complex scientific problems in nuclear physics and astrophysics. In particular, it has been instrumental in determining properties of atomic nuclei, the core of matter and the fuel of stars.

The forthcoming N = 126 factory will be generating beams of atomic nuclei with a "magic number" of neutrons, 126. As Savard explains, "Physics has seven magic numbers: 2, 8, 20, 28, 50, 82 and 126. Atomic nuclei with these numbers of neutrons or protons are exceptionally stable. This stability makes them ideal for research purposes in general."

Scientists at ATLAS will be generating N = 126 nuclei to test a reigning theory of astrophysics—that the rapid capture of neutrons during the explosion and collapse of massive stars and the collision of neutron stars is responsible for the formation of about half the heavy elements from iron through uranium.

The N = 126 factory will be accelerating a beam composed of a xenon isotope with 82 neutrons into a target composed of a platinum isotope with 120 neutrons. The resulting collisions will transfer neutrons from the xenon beam into a platinum target, yielding isotopes with 126 neutrons and close to that amount. The very heavy neutron-rich isotopes are directed to experimental stations for study.

"The planned studies at ATLAS will provide the first data on neutron-rich isotopes with around 126 neutrons and should play a critical role in understanding the formation of heavy elements, the last stage in the evolution of stars," said Savard. "These and other studies will keep ATLAS at the frontier of science."

G. Savard et al, The N = 126 factory: A new facility to produce very heavy neutron-rich isotopes, Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms (2019). DOI: 10.1016/j.nimb.2019.05.024

A.A. Valverde et al. A cooler-buncher for the N=126 factory at Argonne National Laboratory, Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms (2019). DOI: 10.1016/j.nimb.2019.04.070


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  • (Score: 4, Interesting) by stormwyrm on Tuesday March 10 2020, @02:49PM (1 child)

    by stormwyrm (717) on Tuesday March 10 2020, @02:49PM (#969066) Journal
    Neutron stars have been observed colliding with each other [soylentnews.org], with explosive results. The process often results in a small black hole remnant, but most of the rest of the fragments of neutron star matter are blasted away to become very heavy atomic nuclei. These neutron star collisions and resultant "kilonovae" seem to be the primary process by which elements much heavier than iron, such as gold, uranium, etc., are produced. I believe this is what they are referring to with the phrase "collision of neutron stars". It's not the capture of external neutrons by a neutron star, but what occurs in the explosive collisions of neutron stars with each other. Free neutrons are thought to be produced by the process in great abundance, to be captured by larger fragments to produce heavy elements. This was for a long time only a hypothetical process until such an event was finally observed directly in 2017, thanks to LIGO.
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  • (Score: 2) by FatPhil on Wednesday March 11 2020, @12:08AM

    by FatPhil (863) <pc-soylentNO@SPAMasdf.fi> on Wednesday March 11 2020, @12:08AM (#969352) Homepage
    The process that takes nothing but neutrons, and which produces matching pairs of protons and electrons stably bound to the remaining neutrons, really shouldn't be called "neutron capture", given that it's neutron decay.
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