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Neutrinos and Heavy-Element Nucleosynthesis Brad Meyer Clemson University.

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Presentation on theme: "Neutrinos and Heavy-Element Nucleosynthesis Brad Meyer Clemson University."— Presentation transcript:

1 Neutrinos and Heavy-Element Nucleosynthesis Brad Meyer Clemson University

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3 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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6 Alpha-Effect I Fuller and Meyer 1995 Neutrino captures during buildup of 4 He Can drastically increase Y e =>reduce efficacy of the r-process

7 Meyer, McLaughlin, and Fuller 1998

8 Alpha Effect II Meyer 1995 Spall p’s from 4 He late in expansion These protons form 3 H 3 H + 4 He  7 Li  Heavy nuclei—reduce neutron to seed ratio

9 Meyer 1995

10 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

11 Meyer et al. 1992

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15 Neutrino Capture on All Species SpeciesOverproduction 94 Mo2.9 x Mo2.1 x Se1.9 x Sr1.8 x Mo1.7 x 10 6

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17 Capture on Z < 40 SpeciesOverproduction 74 Se1.8 x Sr1.7 x Zr1.4 x Zr9.6 x Mo7.8 x 10 5

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21 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 effects—I.e. Understand supernovae.


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