Synonymer & Information om | Engelska ordet R-PROCESS

Exempel på hur man kan använda R-PROCESS i en mening

• In nuclear astrophysics, the rapid neutron-capture process, also known as the r-process, is a set of nuclear reactions that is responsible for the creation of approximately half of the atomic nuclei heavier than iron, the "heavy elements", with the other half produced by the p-process and s-process.
• The r-process dominates in environments with higher fluxes of free neutrons; it produces heavier elements and more neutron-rich isotopes than the s-process.
• This led to the original idea for the production of p-nuclei: free protons (the nuclei of hydrogen atoms are present in stellar plasmas) should be captured on heavy nuclei (seed nuclei) also already present in the stellar plasma (previously produced in the s-process and/or r-process).
• Heavier nuclides may be created instantaneously by physical processes, both natural (via the r-process) and artificial, though rapidly decay to more stable nuclides.
• Compared to other ultra-metal-poor, r-process enriched stars (as CS22892-052, BD +17° 3248, HE 1523-0901) CS31082-001 has higher abundances of the actinides (Th, U), but a surprisingly low Pb abundance.
• 6 million years – orders of magnitude longer than that of any known isotope beyond curium, and long enough to study as a possible extinct radionuclide that would be produced by the r-process.
• Comparing the observed abundances for a stable element such as europium (Z=63) and the radioactive element thorium (Z=90) to calculated abundances of an r-process in a type II supernova explosion (as from the universities at Mainz and Basel groups of Karl-Ludwig Kratz and Friedrich-Karl Thielemann) have allowed observers to determine the age of this star to be about 13 billion years.
• The University of Mainz and University of Basel groups of Karl-Ludwig Kratz and Friedrich-Karl Thielemann performed a comparison between the observed abundances for the stable element europium (Z=63) and the radioactive elements thorium (Z=90) and uranium (Z=92) to the calculated abundances of an r-process in a Type II supernova explosion.
• The nuclear structure data are also applied by Kratz to nucleosynthesis, especially the astrophysical r-process.
• It is a nucleosynthesis process and, along with the s-process and the r-process, may be responsible for the generation of many of the heavy elements present in the universe.
• CEMP-no – (celestial object) Carbon-enhanced metal-poor star with no enhancement of elements produced by the r-process or s-process nucleosynthesis.
• This suggests that most nickel is produced in supernovas in the r-process of neutron capture from nickel-56 immediately after the core-collapse, with any nickel-56 that escapes the supernova explosion rapidly decaying to cobalt-56 and then stable iron-56.
• 6, while the proportions of strontium, yttrium, zirconium, barium and the lanthanide elements suggest that the s-process has made no contribution to the material present in the star: in HD 122563, all these elements are products of the r-process instead.
• These stable even-proton odd-neutron nuclides tend to be uncommon by abundance in nature, generally because, to form and enter into primordial abundance, they must have escaped capturing neutrons to form yet other stable even-even isotopes, during both the s-process and r-process of neutron capture, during nucleosynthesis in stars.
• These mergers are thought to produce gamma-ray bursts and emit bright electromagnetic radiation, called "kilonovae", due to the radioactive decay of heavy r-process nuclei that are produced and ejected fairly isotropically during the merger process.
• Later, with collaborators, he demonstrated decompressing neutron-star matter from both neutron star-black holes and neutron star-neutron star mergers would form a natural r-process that would match observed patterns.

Förberedelsen av sidan tog: 346,85 ms.