Term
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Definition
Fragmentation of heavier nuclei by cosmic-ray bombardment
Accounts for abundance of elements not synthesised in
thermonuclear reactions.
Explains existence and low abundance of some elements
e.g. 6Li, 7Li, 9Be, 10B, 11B |
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Term
| p-process (proton capture) |
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Definition
Occur in supernova
Makes small contribution to elemental abundance for elements synthesised
by the s- or r-processes
Explains existence and low abundance of some elements
e.g.190Pt or 168Yb |
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Term
| r-process (rapid neutron addition) |
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Definition
Timescale 0.01 – 10s
Lots of neutrons added to nuclei unstable
Rapid - decay : 8-10 - emissions cascade to the next stable isotope
-->Increased abundance peaks at 80, 30 and 194 as 8-10 mass units
below nuclides associated with the s process. |
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Term
| s-process (slow neutron addition) |
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Definition
Timescale 102 – 105 years
Collision of nucleus with neutron heavier nucleus
Unstable nuclei formed decay by electron emission (-)
-->formation of elements of mass 63-209 and non -process nuclei
in 23-46 range |
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Term
| Neutron capture cross-section |
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Definition
| Build-up of certain isotopes e.g. 138Ba, 218Pb, 209Bi |
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Term
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Definition
s-process (slow neutron addition)--->Occurs in red giants
r-process (rapid neutron addition)--->Occurs in supernovae |
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Term
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Definition
Supernova
Violent explosion during supernova – massive release of energy
Interconversions between nuclei, free protons and free neutrons
Explains abundance of Ti to Cu |
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