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S T Petcov - One of the best experts on this subject based on the ideXlab platform.
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diffractive like or parametric resonance like enhancement of the Earth day night effect for solar neutrinos crossing the Earth core
Physics Letters B, 1998Co-Authors: S T PetcovAbstract:Abstract It is shown that the strong enhancement of the Earth (day-night) effect for solar neutrinos crossing the Earth core in the case of the small mixing angle MSW νe→νμ(τ) transition solution of the solar neutrino problem is due to a new resonance effect in the solar neutrino transitions in the Earth and not just to the MSW effect in the core. The effect is in many respects similar to the electron paramagnetic resonance. The conditions for existence of this new resonance effect are discussed. They include specific constraints on the neutrino oscillation lengths in the Earth Mantle and in the Earth core, thus the resonance is a “neutrino oscillation length resonance”. The effect exhibits strong dependence on the neutrino energy. Analytic expression for the probability accounting for the solar neutrino transitions in the Earth, which provides a high precision description of the transitions, including the new resonance effect, is derived. The implications of our results for the searches of the day-night asymmetry in the solar neutrino experiments are also briefly discussed. The new resonance effect is operative also in the νμ→νe (νe→νμ) transitions of atmospheric neutrinos crossing the Earth core.
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diffractive like or parametric resonance like enhancement of the Earth day night effect for solar neutrinos crossing the Earth core
arXiv: High Energy Physics - Phenomenology, 1998Co-Authors: S T PetcovAbstract:It is shown that the strong enhancement of the Earth (day-night) effect for solar neutrinos crossing the Earth core in the case of the small mixing angle MSW electron neutrino to muon (tau) neutrino transition solution of the solar neutrino problem is due to a new resonance effect in the solar neutrino transitions in the Earth and not just to the MSW effect in the core. The effect is in many respects similar to the electron paramagnetic resonance. The conditions for existence of this new resonance effect are discussed. They include specific constraints on the neutrino oscillation lengths in the Earth Mantle and in the Earth core, thus the resonance is a ``neutrino oscillation length resonance''. The effect exhibits strong dependence on the neutrino energy. Analytic expression for the probability accounting for the solar neutrino transitions in the Earth, which provides a high precision description of the transitions, including the new resonance effect, is derived. The implications of our results for the searches of the day-night asymmetry in the solar neutrino experiments are briefly discussed. The new resonance effect is operative also in the muon neutrino to electron neutrino (electron neutrino to muon neutrino) transitions of atmospheric neutrinos crossing the Earth core.
Daniel Herwartz - One of the best experts on this subject based on the ideXlab platform.
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the triple oxygen isotope composition of the Earth Mantle and understanding δo17 variations in terrestrial rocks and minerals
Earth and Planetary Science Letters, 2014Co-Authors: Andreas Pack, Daniel HerwartzAbstract:Abstract It has been shown in numerous studies that terrestrial rocks and minerals fall on a line with slope ∼0.52 in a δ O 17 vs. δ O 18 diagram. In this study, we present new data on the triple isotope composition of the Earth Mantle, crustal materials and low-T aqueous precipitates. Crustal materials show distinct variations in Δ O 17 suggesting that the concept of a single terrestrial mass fractionation is invalid on small-scale. Observable variations in individual fractionation slopes θ are interpreted as temperature effects. We show that the Earth Mantle is isotopically homogeneous and confirm the recent finding that the Earth Mantle has a negative Δ O 17 . The difference in δ O 18 and Δ O 17 between seawater and oceanic crust is discussed with respect to the effects of low- and high-temperature water–rock interaction.
David Davies - One of the best experts on this subject based on the ideXlab platform.
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nusselt rayleigh number scaling for spherical shell Earth Mantle simulation up to a rayleigh number of 109
Physics of the Earth and Planetary Interiors, 2009Co-Authors: M. Wolstencroft, J.h. Davies, David DaviesAbstract:Abstract An investigation of the power law relationship between Nusselt number (Nu) and Rayleigh number (Ra) for Earth’s convecting Mantle is presented. The Nu(Ra) relationship was calculated from the results of a model with three dimensional spherical geometry and free slip boundary conditions. Both basally and internally heated convection has been examined. For Nu ( Ra ) = a Ra β , β was found to be 0.294 ± 0.004 for basally heated systems, which is lower than the value of 1/3 suggested by conventional boundary layer theory. The exponent β = 0.337 ± 0.009 for internally heated systems, when the internally heated Ra is converted to a basally heated equivalent for comparison. The influence of the method used to calculate β was also considered, with particular attention paid to high Ra. As an example of the significance of β = 0.29 rather than 1/3, a Ra of 1 0 9 results in a surface heat flux which is ≈ 32% lower. Within the range of Ra used in this study, there is no evidence that β changes at high Ra. Therefore, that mechanism cannot be used to moderate Mantle temperature when projecting back to early Earth conditions. The differing planform of basally and internally heated models was shown to result in different scaling relationships between root mean square surface velocity and Ra for the two modes of heating, in particular, a much lower surface velocity for internally heated cases relative to equivalent Ra basally heated cases.
Thomas S Kruijer - One of the best experts on this subject based on the ideXlab platform.
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tungsten isotopes and the origin of the moon
Earth and Planetary Science Letters, 2017Co-Authors: Thomas S Kruijer, Thorsten KleineAbstract:Abstract The giant impact model of lunar origin predicts that the Moon mainly consists of impactor material. As a result, the Moon is expected to be isotopically distinct from the Earth, but it is not. To account for this unexpected isotopic similarity of the Earth and Moon, several solutions have been proposed, including (i) post-giant impact Earth–Moon equilibration, (ii) alternative models that make the Moon predominantly out of proto-Earth Mantle, and (iii) formation of the Earth and Moon from an isotopically homogeneous disk reservoir. Here we use W isotope systematics of lunar samples to distinguish between these scenarios. We report high-precision 182W data for several low-Ti and high-Ti mare basalts, as well as for Mg-suite sample 77215, and lunar meteorite Kalahari 009, which complement data previously obtained for KREEP-rich samples. In addition, we utilize high-precision Hf isotope and Ta/W ratio measurements to empirically quantify the superimposed effects of secondary neutron capture on measured 182W compositions. Our results demonstrate that there are no resolvable radiogenic 182W variations within the Moon, implying that the Moon differentiated later than 70 Ma after Solar System formation. In addition, we find that samples derived from different lunar sources have indistinguishable 182W excesses, confirming that the Moon is characterized by a small, uniform ∼+26 parts-per-million excess in 182W over the present-day bulk silicate Earth. This 182W excess is most likely caused by disproportional late accretion to the Earth and Moon, and after considering this effect, the pre-late veneer bulk silicate Earth and the Moon have indistinguishable 182W compositions. Mixing calculations demonstrate that this Earth–Moon 182W similarity is an unlikely outcome of the giant impact, which regardless of the amount of impactor material incorporated into the Moon should have generated a significant 182W excess in the Moon. Consequently, our results imply that post-giant impact processes might have modified 182W, leading to the similar 182W compositions of the pre-late veneer Earth's Mantle and the Moon.
J P Lowman - One of the best experts on this subject based on the ideXlab platform.
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emulating the thermal structure of spherical shell convection in plane layer geometry Mantle convection models
Physics of the Earth and Planetary Interiors, 2010Co-Authors: K A Ofarrell, J P LowmanAbstract:Abstract In a uniform property spherical shell with the same inner to outer radius ratio, f , as the Earth's Mantle, a bottom heating Rayleigh number, Ra , of 10 7 and a nondimensional internal heating rate, H , of 23 (arguably Earth-like values) are insufficient to heat the mean temperature, θ , above the mean of the boundary value temperatures (nondimensional value 0.5). Thus, to attain spherical shell-type temperatures in a plane-layer geometry system, some degree of internal cooling is required. We present the findings from 68 calculations of three-dimensional plane-layer convection featuring a range of Rayleigh numbers and internal heating and cooling rates. Observed mean temperatures are fit with a power–law scaling and combined with the results from spherical shell geometry convection studies to obtain a single equation relating θ , Ra , H and f . For a given Rayleigh number, the derived expression can be used to calculate an appropriate heating or cooling rate for a plane-layer convection model in order to obtain the θ of a spherical system described by f . Encouragingly, we find that at a Rayleigh number consistent with estimates of the effective value of Ra for the Earth's Mantle, geotherms are similar for an appropriately cooled plane-layer system and a spherical shell model featuring a value for H based on estimates of the present-day rate of Mantle internal heating. In particular, our findings have important implications for plane-layer geometry numerical models of Mantle convection featuring temperature-dependent parameters and laboratory tank models. For example, we conclude that disregarding internal heating is most appropriate for modelling terrestrial Mantle convection in a plane-layer geometry. Moreover, because cooling a plane-layer model becomes increasingly relevant when emulating spherical shell convection at higher Rayleigh numbers, our study indicates important considerations for modelling super-Earth Mantle dynamics in plane-layer convection studies.
