Observation of geo-neutrinos

• DOI: 10.1016/j.physletb.2010.03.051
• Publication Date: 2010-03-21T04:13:13Z
• Authors: G. Bellini; J. Benziger; S. Bonetti; M. Buizza Avanzini; B. Caccianiga; L. Cadonati; F. Calaprice; C. Carraro; A. Chavarria; F. Dalnoki-Veress; D. D'Angelo; S. Davini; H. de Kerret; A. Derbin; A. Etenko; G. Fiorentini; K. Fomenko; D. Franco; C. Galbiati; S. Gazzana; C. Ghiano; M. Giammarchi; M. Goeger-Neff; A. Goretti; E. Guardincerri; S. Hardy; Aldo Ianni; Andrea Ianni; M. Joyce; V.V. Kobychev; Y. Koshio; G. Korga; D. Kryn; M. Laubenstein; M. Leung; T. Lewke; E. Litvinovich; B. Loer; P. Lombardi; L. Ludhova; I. Machulin; S. Manecki; W. Maneschg; G. Manuzio; Q. Meindl; E. Meroni; L. Miramonti; M. Misiaszek; D. Montanari; V. Muratova; L. Oberauer; M. Obolensky; F. Ortica; M. Pallavicini; L. Papp; L. Perasso; S. Perasso; A. Pocar; R.S. Raghavan; G. Ranucci; A. Razeto; A. Re; B. Ricci; P. Risso; A. Romani; D. Rountree; A. Sabelnikov; R. Saldanha; C. Salvo; S. Schönert; H. Simgen; M. Skorokhvatov; O. Smirnov; A. Sotnikov; S. Sukhotin; Y. Suvorov; R. Tartaglia; G. Testera; D. Vignaud; R.B. Vogelaar; F. von Feilitzsch; J. Winter; M. Wojcik; A. Wright; M. Wurm; J. Xu; O. Zaimidoroga; S. Zavatarelli; G. Zuzel
• Keywords: Borexino

Geo-neutrinos, electron anti-neutrinos produced in beta decays of naturally occurring radioactive isotopes the Earth, are a unique direct probe our planet's interior. We report first observation at more than 3$\sigma$ C.L. geo-neutrinos, performed with Borexino detector Laboratori Nazionali del Gran Sasso. Anti-neutrinos detected through neutron inverse decay reaction. With 252.6 ton-yr fiducial exposure after all selection cuts, we 9.9^{+4.1}_{-3.4}(^{+14.6}_{-8.2}) geo-neutrino events, errors corresponding to 68.3%(99.73%) From $\ln{\cal{L}}$ profile, statistical significance corresponds 99.997% Our measurement geo-neutrinos rate is 3.9^{+1.6}_{-1.3}(^{+5.8}_{-3.2}) events/(100ton-yr). This rejects hypothesis an active geo-reactor Earth's core power above 3 TW 95% The observed prompt positron spectrum 2.6 MeV compatible that expected from european nuclear reactors (mean base line approximately 1000 km). reactor excludes non-oscillation 99.60%