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Title: Mantle geoneutrinos in KamLAND and Borexino
Authors: G. Fiorentini, G. L. Fogli, E. Lisi, F. Mantovani, A. M. Rotunno

The KamLAND and Borexino experiments have observed, each at ~4 sigma level, signals of electron antineutrinos produced in the decay chains of thorium and uranium in the Earth's crust and mantle (Th and U geoneutrinos). Various pieces of geochemical and geophysical information allow an estimation of the crustal geoneutrino flux components with relatively small uncertainties. The mantle component may then be inferred by subtracting the estimated crustal flux from the measured total flux. To this purpose, we analyse in detail the experimental Th and U geoneutrino event rates in KamLAND and Borexino, including neutrino oscillation effects. We estimate the crustal flux at the two detector sites, using state-of-the-art information about the Th and U distribution on global and local scales. We find that crust-subtracted signals show hints of a residual mantle component, emerging at ~2.4 sigma level by combining the KamLAND and Borexino data. The inferred mantle flux slightly favours scenarios with relatively high Th and U abundances, within ±1 sigma uncertainties comparable to the spread of predictions from recent mantle models.

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Caltech researchers obtain highest-pressure vibrational spectrum of iron

Identifying the composition of the earth's core is key to understanding how our planet formed and the current behaviour of its interior. While it has been known for many years that iron is the main element in the core, many questions have remained about just how iron behaves under the conditions found deep in the earth. Now, a team led by mineral-physics researchers at the California Institute of Technology (Caltech) has honed in on those behaviours by conducting extremely high-pressure experiments on the element.
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Metal undergoes novel transition under extreme pressure

Under extreme pressures and temperatures, one of the main metals of the Earth's interior has exhibited a never-before-seen transition.
Iron oxide was subjected to conditions similar to those at the depth where the Earth's innermost two layers meet.
At 1,650C and 690,000 times sea-level pressure, the metal changed the degree to which it conducted electricity.
But, as the team outlined in Physical Review Letters, the metal's structure was surprisingly unchanged.

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Earth's core deprived of oxygen

The composition of the Earth's core remains a mystery. Scientists know that the liquid outer core consists mainly of iron, but it is believed that small amounts of some other elements are present as well. Oxygen is the most abundant element in the planet, so it is not unreasonable to expect oxygen might be one of the dominant "light elements" in the core. However, new research from a team including Carnegie's Yingwei Fei shows that oxygen does not have a major presence in the outer core. This has major implications for our understanding of the period when the Earth formed through the accretion of dust and clumps of matter. Their work is published Nov. 24 in Nature.
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Geomagnetic Secular Variation as a Window on the Dynamics of Earth's Core

2010 AGU Fall Meeting - Edward Bullard Lecture Geomagnetic Secular Variation as a Window on the Dynamics of Earth's Core Presented by A. Jackson, Institute for Geophysics, ETH Zürich



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How Old is the Earths Inner Core?

Another discovery by a Michigan Technological University researcher could send shockwaves across the world of earth science.
Aleksey Smirnov, assistant professor of geophysics, with colleagues from the University of Rochester and Yale University, has discovered that the earths inner core could actually be at least 1.2 billion years older than previously thought.

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Magnetic mysteries of Earth's Core

Earthquakes, explosions and observations of Earth's ever-changing magnetic field are helping scientists open up a new window on the heart of our planet.
When Jules Verne wrote A Journey to the Centre of the Earth over 100 years ago, he imagined a place of glowing crystals and a turbulent sea, complete with prehistoric animals and giant mushrooms.
What was actually beneath our feet was a complete enigma. Even to this day scientists astonishingly know more about the rings of Saturn than they do about the core of our own planet.

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Berkeley Lab scientists join their KamLAND colleagues to measure the radioactive sources of Earth's heat flow

What spreads the sea floors and moves the continents? What melts iron in the outer core and enables the Earth's magnetic field? Heat. Geologists have used temperature measurements from more than 20,000 boreholes around the world to estimate that some 44 terawatts (44 trillion watts) of heat continually flow from Earth's interior into space. Where does it come from?
Radioactive decay of uranium, thorium, and potassium in Earth's crust and mantle is a principal source, and in 2005 scientists in the KamLAND collaboration, based in Japan, first showed that there was a way to measure the contribution directly. The trick was to catch what KamLAND dubbed geoneutrinos - more precisely, geo-antineutrinos - emitted when radioactive isotopes decay. (KamLAND stands for Kamioka Liquid-scintillator Antineutrino Detector.)

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The Earth's core is melting...and freezing

The inner core of the Earth is simultaneously melting and freezing due to circulation of heat in the overlying rocky mantle, according to new research from the University of Leeds.
The findings, published today in Nature, could help us understand how the inner core formed and how the outer core acts as a 'geodynamo', which generates the planet's magnetic field. The study was a collaboration between the University of Leeds, UC San Diego and the Indian Institute of Technology.

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Tiny 3-D images from Stanford and SLAC shed light on origin of Earth's core

To answer the big questions, it often helps to look at the smallest details. That is the approach Stanford mineral physicist Wendy Mao is taking to understanding a major event in Earth's inner history. Using a new technique to scrutinize how minute amounts of iron and silicate minerals interact at ultra-high pressures and temperatures, she is gaining insight into the biggest transformation Earth has ever undergone - the separation of its rocky mantle from its iron-rich core approximately 4.5 billion years ago.
The technique, called high-pressure nanoscale X-ray computed tomography, is being developed at SLAC National Accelerator Laboratory. With it, Mao is getting unprecedented detail - in three-dimensional images - of changes in the texture and shape of molten iron and solid silicate minerals as they respond to the same intense pressures and temperatures found deep in the Earth.
Mao will present the results of the first few experiments with the technique at the annual meeting of the American Geophysical Union in San Francisco on Thursday, Dec. 16.

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