10 research outputs found
CN-Cycle Solar Neutrinos and Sun's Primordial Core Metalicity
We argue that it may be possible to exploit neutrinos from the CN cycle and
pp chain to determine the primordial solar core abundances of C and N at an
interesting level of precision. Such a measurement would allow a comparison of
the Sun's deep interior composition with it surface, testing a key assumption
of the standard solar model (SSM), a homogeneous zero-age Sun. It would also
provide a cross-check on recent photospheric abundance determinations that have
altered the once excellent agreement between the SSM and helioseismology. As
further motivation, we discuss a speculative possibility in which photospheric
abundance/helioseismology puzzle is connected with the solar-system metal
differentiation that accompanied formation of the gaseous giant planets.
The theoretical relationship between core C and N and the 13N and 15O solar
neutrino fluxes can be made more precise (and more general) by making use of
the Super-Kamiokande and SNO 8B neutrino capture rates, which calibrate the
temperature of the solar core. The primordial C and N abundances can then be
obtained from these neutrino fluxes and from a product of nuclear rates, with
little residual solar model dependence. We describe some of the recent
experimental advances that could allow this comparison to be made
(theoretically) at about the 9% level, and note that this uncertainty may be
reduced further due to ongoing work on the S-factor for 14N(p,gamma). The
envisioned measurement might be possible in deep, large-volume detectors using
organic scintillator, e.g., Borexino or SNO+Comment: 33 pages, 4 figure
Prospects for studying the solar CNO cycle by means of a lithium neutrino detector
Lithium detectors have a high sensitivity to CNO neutrinos from the Sun. The
present experimental data and prospects for future experiments on the detection
of CNO neutrinos are discussed. A nonstationary case is considered when the
flux of 13N neutrinos is higher than the standard solar model predicts due to
the influx of fresh material from the peripheral layers to the solar core.Comment: 12 pages, 5 figures, a thoroughly revised version, reported at
International Symposium "Physics of Massive Neutrinos" at MILOS (Greece)
19-23 May 200
Using the standard solar model to constrain solar composition and nuclear reaction S factors
While standard solar model (SSM) predictions depend on approximately 20 input parameters, SSM neutrino flux predictions are strongly correlated with a single model output parameter, the core temperature T-c. Consequently, one can extract physics from solar neutrino flux measurements while minimizing the consequences of SSM uncertainties, by studying flux ratios with appropriate power-law weightings tuned to cancel this T-c dependence. We reexamine an idea for constraining the primordial C + N content of the solar core from a ratio of CN-cycle O-15 to pp-chain B-8 neutrino fluxes, showing that non-nuclear SSM uncertainties in the ratio are small and effectively governed by a single parameter, the diffusion coefficient. We point out that measurements of both CN-I cycle neutrino branches-O-15 and N-13 beta-decay-could, in principle, lead to separate determinations of the core C and N abundances, due to out-of-equilibrium CN-cycle burning in the cooler outer layers of the solar core. Finally, we show that the strategy of constructing Âżminimum uncertaintyÂż neutrino flux ratios can also test other properties of the SSM. In particular, we demonstrate that a weighted ratio of Be-7 and B-8 fluxes constrains a product of S-factors to the same precision currently possible with laboratory data