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Creation of heavy elements: r and s process

  1. May 25, 2005 #1
    Hi, i'm studying my astronomy course at the moment and i have question about the r- and s-process. As I understand it, in the r-process, the time between capturing two neutrons is shorter than the averge beta decay half life, right? So i'm guessing there have to be a lot of neutrons around for the r process to take place. But where do all these neutrons come from?
  2. jcsd
  3. May 25, 2005 #2


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    It is mostly ionized H atoms, simply protons, among free electrons (=plasma) that gets the stars going in the core. See mainly pages 3-5 of this link:

    http://www.genesismission.org/educate/scimodule/SunandSolar/Final%20Linked%20SSW/6AppendicesCari/a.pdf [Broken]
    Last edited by a moderator: May 2, 2017
  4. May 29, 2005 #3


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    Neutrons can come from certain fusion reactions of light isotopes, and from spallation reactions in the heavier nuclides.

    See also - https://www.physicsforums.com/showpost.php?p=506354&postcount=7, which mentions reactions concerning production of superheavy elements.
    Last edited: May 29, 2005
  5. May 29, 2005 #4


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    Welcome to Physics Forums, Gideon!

    Others have already answered your question, in one sense; perhaps (however) you meant something like 'in what environments are such floods of neutrons likely to occur?'

    Supernovae, of the core collapse kind - can you now find out why such environments are expected to be so 'neutron-rich'?
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