Abstract
The recent long-term shutdown of Japanese nuclear reactors has resulted in a significantly reduced reactor flux at KamLAND. This running condition provides a unique opportunity to confirm and constrain backgrounds for the reactor oscillation analysis. The data set also has improved sensitivity for other signals, in particular ’s produced in -decays from and within the Earth’s interior, whose energy spectrum overlaps with that of reactor ’s. Including constraints on from accelerator and short-baseline reactor neutrino experiments, a combined three-flavor analysis of solar and KamLAND data gives fit values for the oscillation parameters of , , and . Assuming a chondritic Th/U mass ratio, we obtain events from and , corresponding to a geo flux of at the KamLAND location. We evaluate various bulk silicate Earth composition models using the observed geo rate.
1 More- Received 19 March 2013
DOI:https://doi.org/10.1103/PhysRevD.88.033001
© 2013 American Physical Society