The KamLAND Collaboration
We present the results of a search for extraterrestrial electron
antineutrinos ($\bar{\nu}_{e}$'s) in the energy range $8.3 MeV <
E_{\bar{\nu}_{e}} < 31.8 MeV$ using the KamLAND detector. In an exposure of
4.53 kton-year, we identify 25 candidate events. All of the candidate events
can be attributed to background, most importantly neutral current atmospheric
neutrino interactions, setting an upper limit on the probability of $^{8}$B
solar $\nu_{e}$'s converting into $\bar{\nu}_{e}$'s at $5.3 \times 10^{-5}$
(90% C.L.), if we assume an undistorted $\bar{\nu}_{e}$ shape. This limit
corresponds to a solar $\bar{\nu}_{e}$ flux of $93 cm^{-2} s^{-1}$ or an event
rate of $1.6 events (kton-year)^{-1}$ above the energy threshold
$(E_{\bar{\nu}_{e}} > 8.3 MeV)$. The present data also allows us to set more
stringent limits on the diffuse supernova neutrino flux and on the annihilation
rates for light dark matter particles.
View original:
http://arxiv.org/abs/1105.3516
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