11B and constraints on neutrino oscillations and spectra from neutrino nucleosynthesis.

National Superconducting Cyclotron Laboratory and Joint Institute for Nuclear Astrophysics, 1 Cyclotron, Michigan State University, East Lansing, Michigan 48824-1321, USA.
Physical Review Letters (Impact Factor: 7.73). 04/2011; 106(15):152501. DOI: 10.1103/PhysRevLett.106.152501
Source: PubMed

ABSTRACT We study the sensitivity to variations in the triple-alpha and 12C(α,γ)16O reaction rates, of the yield of the neutrino-process isotopes 7Li, 11B, 19F, 138La, and 180Ta in core-collapse supernovae. Compared to solar abundances, less than 15% of 7Li, about 25%-80% of 19F, and about half of 138La is produced in these stars. Over a range of ±2σ for each helium-burning rate, 11B is overproduced and the yield varies by an amount larger than the variation caused by the effects of neutrino oscillations. The total 11B yield, however, may eventually provide constraints on supernova neutrino spectra.

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    ABSTRACT: We present two new primary mechanisms for the synthesis of the rare nucleus 9Be, both triggered by ν-induced production of 3H followed by 4He(3H,γ)7Li in the He shells of core-collapse supernovae. For progenitors of ∼8M⊙, 7Li(3H,n0)9Be occurs during the rapid expansion of the shocked He shell. Alternatively, for ultra-metal-poor progenitors of ∼11–15M⊙, 7Li(n,γ)8Li(n,γ)9Li(e-ν̅ e)9Be occurs with neutrons produced by 4He(ν̅ e,e+n)3H, assuming a hard effective ν̅ e spectrum from oscillations (which also leads to heavy element production through rapid neutron capture) and a weak explosion (so the 9Be survives shock passage). We discuss the associated production of 7Li and 11B, noting patterns in LiBeB production that might distinguish the new mechanisms from others.
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    ABSTRACT: We study the nuclear weak response in light-to-heavy mass nuclei and calculate neutrino-nucleus cross sections. We apply these cross sections to the explosive nucleosynthesis in core-collapse supernovae and find that several isotopes of rare elements 7Li, 11B, 138La, 180Ta and several others are predominantly produced by the neutrino-process nucleosynthesis. We discuss how to determine the suitable neutrino spectra of three different flavors and their anti-particles in order to explain the observed solar system abundances of these isotopes, combined with Galactic chemical evolution of the light nuclei and the heavy r-process elements. Light-mass nuclei like 7Li and 11B, which are produced in outer He-layer, are strongly affected by the neutrino flavor oscillation due to the MSW (Mikheyev-Smirnov-Wolfenstein) effect, while heavy-mass nuclei like 138La, 180Ta and r-process elements, which are produced in the inner O-Ne-Mg layer or the atmosphere of proto-neutron star, are likely to be free from the MSW effect. Using such a different nature of the neutrino-process nucleosynthesis, we study the neutrino oscillation effects on their abundances, and propose a new novel method to determine the unknown neutrino oscillation parameters, θ13 and mass hierarchy, simultaneously. There is recent evidence that some SiC X grains from the Murchison meteorite may contain supernova-produced neutrino-process 11B and 7Li encapsulated in the grains. Combining the recent experimental constraints on θ13, we show that although the uncertainties are still large, our method hints at a marginal preference for an inverted neutrino mass hierarchy for the first time.
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    ABSTRACT: A review of evidence on the properties of the A=11A=11 nuclei, with emphasis on material leading to information about the structure of the A=11A=11 systems.
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