r-process


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r-process

A rapid process of nucleosynthesis that is thought to occur when there is a very high flux of neutrons, as in certain supernova explosions. All nuclei with a mass number greater than bismuth–209 (see s-process) and all neutron-rich isotopes heavier than iron have been produced by the r-process. The process involves the capture by a nucleus of two or more neutrons in quick succession. The nucleus will then undergo chains of beta decay, this beta-particle (electron) emission having been suppressed during the rapid capture process. The decay product will be a stable neutron-rich nucleus. Many heavy nuclei can be produced both by the r- and the s-process.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006

r-process

[′är ‚prä·səs]
(nuclear physics)
The synthesis of elements and nuclides in supernovas through rapid captures of neutrons in a matter of seconds, followed by beta decay.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
The observation settles a riddle that has puzzled scientists for more than 60 years: where do gold, platinum, uranium, and other heavy elements, known as r-process elements, come from?
Fowler, but heavier elements required a different thermonuclear chemistry called r-process and lots of free neutrons floating around.
The researchers hope that they might be able to detect the imploding neutron stars as kilonovae, or explosions much dimmer than supernovae that could hint to this so-called r-process formation.
Many of the universe's heaviest elements form primarily through the r-process, a chain of reactions through which atomic nuclei climb the periodic table, swallowing up neutrons and decaying radioactively.
For 50 years, astronomers and nuclear physicists have modeled this rapid process, named the r-process, in order to unravel the cosmic history of the elements.
There's no time for stabilizing beta decays during this rapid neutron capture, or r-process. Only later, after the neutron flood subsides and the material spreads out a bit, will very heavy, unstable atoms have the opportunity to decay into stable isotopes.
Poster topics include the magnesium abundance in 52 B stars, an infrared survey of neutron capture elements in planetary nebulae, new r-process enhanced stars found in the HK-II survey, and the origin of sulfur.
Astronomers believe most of these "r-process elements"-elements much heavier than iron-were created, either in the aftermath of the collapse of massive stars and the associated supernova explosions, or in the merging of binary neutron star systems.
Both elements arise in the r-process, which occurs in supernovae and neutron-star mergers when neutrons bombard nuclei rapidly to create small quantities of heavy elements.