arXiv:1102.4858v1 [nucl-th] 23 Feb 2011
11B and Constraints on Neutrino Oscillations and Spectra from
Sam M. Austin,1, 2, ∗Alexander Heger,3and Clarisse Tur1
1National Superconducting Cyclotron Laboratory,
1 Cyclotron, Michigan State University, East Lansing, MI 48824-1321
Joint Institute for Nuclear Astrophysics
2Department of Physics and Astronomy,
Michigan State University, East Lansing Michigan 48824
3School of Physics and Astronomy, University of Minnesota,
Twin Cities, Minneapolis, MN 55455-0149
Joint Institute for Nuclear Astrophysics†
(Dated: February 25, 2011)
We have studied the sensitivity to variations in the triple alpha and12C(α,γ)16O reaction rates, of
the yield of the neutrino process isotopes7Li,11B,19F,138La, and180Ta in core collapse supernovae.
Compared to solar abundances, less than 15% of7Li, about 25-80% of19F, and about half of138La 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 total11B yield, however, may eventually provide constraints on supernova neutrino spectra.
PACS numbers: 26.30.Jk, 26.50.+x, 14.60.Pq
About 1058neutrinos are emitted during a typical core collapse supernova explosion.
For some time it has been known (see  for a detailed history) that interactions of these
neutrinos with the stellar envelope can produce certain rare nuclei in abundances close to
those observed in nature. These nuclei, called here the neutrino nuclei, include7Li,11B,19F,
138La, and180Ta [1, 2].
It was pointed out  that the production of some of the180Ta and most of the138La by
the neutrino process was sensitive to the electron neutrino temperatures, and might serve to
probe the value of the neutrino oscillation parameter sin22θ13. Recently, [3–5] showed that
the yields of7Li and11B in supernova explosions are also sensitive to sin22θ13and to whether
the neutrino mass hierarchy is normal or inverted. In both cases, this sensitivity arises
because neutrino oscillations can change the neutrino spectra produced during core collapse
supernovae, increasing the average energies of the νeand ¯ νeand affecting the synthesis of the
neutrino nuclei. Since two of the main goals of neutrino physics  are to determine better
the value of sin22θ13and the nature of the mass hierarchy, the possibility that the observed
abundances of the neutrino nuclei might constrain these quantities is of great interest.
Their use for this purpose depends, however, on the robustness of the stellar yield pre-
dictions. Studies of the dependence of nucleosynthesis on the helium burning reaction rates
have shown [7, 8] that both the yields of the more abundant nuclides and stellar structure
are significantly affected. Since the neutrino nuclei result from neutrino induced spallation of
abundant progenitor nuclei, their production depends on the abundances of these nuclei and
on their location within the star, and thereby on the rates of the helium burning reactions.
In this paper, we examine the changes in the production of7Li,11B,19F,138La, and180Ta
caused by changes in the astrophysical helium burning rates within their uncertainty limits,
and compare the yield changes of7Li, and11B, with the predicted [3–5] effects of oscillations.
We then discuss how, and whether, the neutrino process nuclei can be used to constrain
the neutrino spectra from supernovae. We find that the constraints provided by neutrino
process nucleosynthesis are interesting but not yet definitive. Because of the great interest
in these issues it appears that a major effort to sharpen these constraints is warranted; a
discussion of important measurements and calculations is given below.
We used the KEPLER code [9–12] to model the evolution of 15, 20, and 25 solar mass
stars from central hydrogen burning up to core-collapse; a piston placed at the base of the
oxygen shell was then used to simulate the explosion. Following  we assumed a total
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