Neutrinos and Heavy-Element Nucleosynthesis

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Neutrinos and Heavy-Element Nucleosynthesis

• Brad Meyer
• Clemson University

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Neutrinos do two things

• Change nucleons
• Nu n ? p e-
• Antinu p ? n e
• Spall nucleons
• Nu (Z,A) ? (Z,A-1) n
• Nu (Z,A) ? (Z-1,A-1) p

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Alpha-Effect I

• Fuller and Meyer 1995
• Neutrino captures during buildup of 4He
• Can drastically increase Ye gtreduce efficacy of
  the r-process

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Meyer, McLaughlin, and Fuller 1998
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Alpha Effect II

• Meyer 1995
• Spall ps from 4He late in expansion
• These protons form 3H
• 3H 4He ? 7Li ? Heavy nucleireduce neutron to
  seed ratio

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Meyer 1995
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Spallation in the r-Process

• Once the r-process has finished, neutrinos spall
  off neutrons
• Tends to smooth out the abundances but also fills
  in gaps that should be present in the abundance
  distribution

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Meyer et al. 1992
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Neutrino Capture on All Species
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Capture on Z lt 40
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Conclusions

• Neutrinos can play a significant role in
  heavy-element nucleosynthesis in changing
  nucleons and redistributing them
• We understand most of the likely effects of
  neutrinos during nucleosynthesis
• We now need to understanding the setting of these
  effectsI.e. Understand supernovae.