Y. Suvorov - Measurement of geo–neutrinos with Borexino during 1353 days of live time
by
Yury Suvorov(LNGS)
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Europe/Rome
Pontecorvo room (LNGS)
Pontecorvo room
LNGS
Description
We present a measurement of the geo–neutrino signal obtained with the Borexino detector at Laboratori Nazionali del Gran Sasso in Italy. With a fiducial exposure of (3.69 ± 0.16) × 1031 proton × year after all selection cuts and background subtraction, we detected (14.3 ± 4.4) geo–neutrino events with a fixed chondritic mass Th/U ratio of 3.9. This corresponds to a geo–neutrino signal Sgeo = (38.8 ± 12.0) TNU. From the lnL profile, the null geo–neutrino measurement has a probability of 6 × 10-6. If the U and Th components are fitted individually, the relative signals are STh = (10.6 ± 12.7) TNU and SU = (26.5 ± 19.5) TNU. Borexino data alone are compatible with a mantle geo–neutrino signal of (15.4 ± 12.3) TNU, while a combined analysis with the KamLAND data allows to extract a mantle signal of (14.1 ± 8.1) TNU. Borexino data reject the hypothesis of an active geo–reactor in the Earth’s core with a power above 4.5 TW at 95% C.L. Our measurement of a reactor anti–neutrino signal S = 84.5+19.3-18.9 TNU is in agreement with expectations in the presence of neutrino oscillations.
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Yuri Suvorov
University of California
Los Angeles
