COSMOVIA - Virtual Institute of Astroparticle Physics /OBSERVATION OF GEO-NEUTRINOS

Credits

Borexino Collaboration

Observation of Geo-neutrinos

March 1, 2010

Geo-neutrinos, electron anti-neutrinos produced in beta decays of naturally
occurring radioactive isotopes in the Earth, are a unique direct probe of our
planet's interior...

Geo-neutrinos, electron anti-neutrinos produced in beta decays of naturally
occurring radioactive isotopes in the Earth, are a unique direct probe of our
planet's interior. We report the first observation of geo-neutrinos, performed
with the Borexino detector at Laboratori Nazionali del Gran Sasso.

borexino

Anti-neutrinos are detected through the neutron inverse beta decay reaction.
With a 252.6 ton-yr fiducial exposure after all selection cuts, we detected 9.9^{+4.1}_{-3.4}(^{+14.6}_{-8.2}) geo-neutrino events, with errors corresponding to a 68.3%(99.73%) C.L. From the $\ln{\cal{L}}$ profile, the statistical significance of the Borexino geo-neutrino observation corresponds to a 99.997% C.L. Our measurement of the geo-neutrinos rate is 3.9^{+1.6}_{-1.3}(^{+5.8}_{-3.2}) events/(100ton-yr). This measurement rejects the hypothesis of an active geo-reactor in the Earth's core with a power above 3 TW at 95% C.L. The observed prompt positron spectrum above 2.6 MeV is compatible with that expected from european nuclear reactors (mean base line of approximately 1000 km). Our measurement of reactor anti-neutrinos excludes the non-oscillation hypothesis at 99.60% C.L.
\\ ( http://arxiv.org/abs/1003.0284 , 55kb)

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Beyond the standard model

Astroparticle physics

Cosmology

Gravitational waves experiments

Astrophysics

Neutrinos

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