Focus: Neutrinos Detected from the Earth’s Mantle

Focus: Neutrinos Detected from the Earth’s Mantle
http://physics.aps.org/articles/v8/79

The steady decay of long-lived radioactive isotopes within the Earth
heats the planet and also sends out streams of neutrinos, which can
be observed by large detectors. The Borexino Collaboration now
reports a new set of data for such “geoneutrinos” and indicates that
at least some of them originate from the Earth’s mantle. The work
could improve researchers’ understanding of how radioactive decays
help drive internal geophysical processes, including the slow
convection of rock in the Earth’s mantle.

Neutrinos are notorious for interacting with matter extremely
rarely—a light-year-thick wall of lead would only stop half of the
neutrinos flying through—so detection is challenging. But using large
detectors, both Borexino and KamLAND, another international
collaboration, have previously detected geoneutrinos with very high
confidence. With more data, researchers hope to gain further
information about the distribution of radioactive isotopes in the
Earth’s interior and about the amount of heat they deliver to various
subterranean regions.

The Borexino detector, which contains 300 metric tons of a fluid that
can emit light flashes in response to particles, operates at the
underground Gran Sasso National Laboratory in Italy and detects
electron antineutrinos, commonly created in nuclear decays. From
December of 2007 through March of 2015, the detector recorded a total
of 77 candidate geoneutrino events, compared with 46 events the team
reported in 2013 [1].

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