Partial radiogenic heat model for Earth revealed by geoneutrino measurements

The Earth has cooled since its formation, yet the decay of radiogenic isotopes, and in particular uranium, thorium and potassium, in the planet’s interior provides a continuing heat source. The current total heat flux from the Earth to space is 44:2±1.0 TW, but the relative contributions from residual primordial heat and radiogenic decay remain uncertain. However, radiogenic decay can be estimated from the flux of geoneutrinos, electrically neutral particles that are emitted during radioactive decay and can pass through the Earth virtually unaffected. Here we combine precise measurements of the geoneutrino flux from the Kamioka Liquid-Scintillator Antineutrino Detector, Japan, with existing measurements from the Borexino detector, Italy.We find that decay of uranium-238 and thorium-232 together contribute 20.0^(+8.8)_(-8.6)TW to Earth’s heat flux. The neutrinos emitted from the decay of potassium-40 are below the limits of detection in our experiments, but are known to contribute 4TW. Taken together, our observations indicate that heat from radioactive decay contributes about half of Earth’s total heat flux. We therefore conclude that Earth’s primordial heat supply has not yet been exhausted

Stratifying derived categories of cochains on certain spaces

In recent years, Benson, Iyengar and Krause have developed a theory of stratification for compactly generated triangulated categories with an action of a graded commutative Noetherian ring. Stratification implies a classification of localizing and thick subcategories in terms of subsets of the prime ideal spectrum of the given ring. In this paper two stratification results are presented: one for the derived category of a commutative ring-spectrum with polynomial homotopy and another for the derived category of cochains on certain spaces. We also give the stratification of cochains on a space a topological content.Comment: 27 page

Numerical methods and calculations for droplet flow, heating and ignition

A numerical method was devised and employed to solve a variety of problems related to liquid droplet combustion. The basic transport equations of mass, momentum and energy were formulated in terms of generalized nonorthogonal coordinates, which allows for adaptive griding and arbitrary particle shape. Example problems are solved for internal droplet heating, droplet ignition and high Reynolds number flow over a droplet

Constraints on θ_(13) from a three-flavor oscillation analysis of reactor antineutrinos at KamLAND

We present new constraints on the neutrino oscillation parameters Δm^2_(21), θ_(12), and θ_(13) from a three flavor analysis of solar and KamLAND data. The KamLAND data set includes data acquired following a radiopurity upgrade and amounts to a total exposure of 3.49 x 10^(32) target-proton-year. Under the assumption of CPT invariance, a two-flavor analysis (θ_(13) = 0) of the KamLAND and solar data yields the best-fit values tan^2θ_(12) = 0.444^(+0.036)_(-0.030) and Δm^2_(21) = 7.50^(+0.19)_(-0.20) x 10^(-5) eV^2; a three-flavor analysis with θ13 as a free parameter yields the best-fit values tan^2θ_(12) = 0.452^(+0.035)_(-0.033), Δm^2_(21) = 7.50^(+0.19)_(-0.20) x 10^(-5) eV^2, and sin^2θ_(13) = 0.020^(+0.016)_(-0.016). This θ_(13) interval is consistent with other recent work combining the CHOOZ, atmospheric and long-baseline accelerator experiments. We also present a new global θ_(13) analysis, incorporating the CHOOZ, atmospheric, and accelerator data, which indicates sin^2θ_(13) = 0.009^(+0.013)-_(0.007). A nonzero value is suggested, but only at the 79% C.L

A computer program for the calculation of laminar and turbulent boundary layer flows

The results are presented of a study to produce a computer program to calculate laminar and turbulent boundary layer flows. The program is capable of calculating the following types of flow: (1) incompressible or compressible, (2) two dimensional or axisymmetric, and (3) flows with significant transverse curvature. Also, the program can handle a large variety of boundary conditions, such as blowing or suction, arbitrary temperature distributions and arbitrary wall heat fluxes. The program has been specialized to the calculation of equilibrium air flows and all of the thermodynamic and transport properties used are for air. For the turbulent transport properties, the eddy viscosity approach has been used. Although the eddy viscosity models are semi-empirical, the model employed in the program has corrections for pressure gradients, suction and blowing and compressibility. The basic method of approach is to put the equations of motion into a finite difference form and then solve them by use of a digital computer. The program is written in FORTRAN 4 and requires small amounts of computer time on most scientific machines. For example, most laminar flows can be calculated in less than one minute of machine time, while turbulent flows usually require three or four minutes

Measurement of the ^8B solar neutrino flux with the KamLAND liquid scintillator detector

We report a measurement of the neutrino-electron elastic scattering rate from ^8B solar neutrinos based on a 123 kton-day exposure of KamLAND. The background-subtracted electron recoil rate, above a 5.5-MeV analysis threshold is 1.49 ± 0.14(stat) ± 0.17(syst) events per kton-day. Interpreted as due to a pure electron flavor flux with a ^8B neutrino spectrum, this corresponds to a spectrum integrated flux of 2.77 ± 0.26(stat) ± 0.32(syst) ×10^6 cm^(−2_s^(−1). The analysis threshold is driven by ^(208)Tl present in the liquid scintillator, and the main source of systematic uncertainty is due to background from cosmogenic ^(11)Be. The measured rate is consistent with existing measurements and with standard solar model predictions which include matter-enhanced neutrino oscillation

Mass Hierarchy Resolution in Reactor Anti-neutrino Experiments: Parameter Degeneracies and Detector Energy Response

Determination of the neutrino mass hierarchy using a reactor neutrino experiment at $\sim$60 km is analyzed. Such a measurement is challenging due to the finite detector resolution, the absolute energy scale calibration, as well as the degeneracies caused by current experimental uncertainty of $|\Delta m^2_{32}|$. The standard $\chi^2$ method is compared with a proposed Fourier transformation method. In addition, we show that for such a measurement to succeed, one must understand the non-linearity of the detector energy scale at the level of a few tenths of percent.Comment: 7 pages, 6 figures, accepted by PR

Production of radioactive isotopes through cosmic muon spallation in KamLAND

Radioactive isotopes produced through cosmic muon spallation are a background for rare-event detection in ν detectors, double-β-decay experiments, and dark-matter searches. Understanding the nature of cosmogenic backgrounds is particularly important for future experiments aiming to determine the pep and CNO solar neutrino fluxes, for which the background is dominated by the spallation production of ^(11)C. Data from the Kamioka liquid-scintillator antineutrino detector (KamLAND) provides valuable information for better understanding these backgrounds, especially in liquid scintillators, and for checking estimates from current simulations based upon MUSIC, FLUKA, and GEANT4. Using the time correlation between detected muons and neutron captures, the neutron production yield in the KamLAND liquid scintillator is measured to be Y_n=(2.8±0.3)×10^(-4) μ^(-1) g^(-1) cm^2. For other isotopes, the production yield is determined from the observed time correlation related to known isotope lifetimes. We find some yields are inconsistent with extrapolations based on an accelerator muon beam experiment