Abstract
We report a measurement of the neutrino-electron elastic scattering rate from B solar neutrinos based on a 123 kton-day exposure of KamLAND. The background-subtracted electron recoil rate, above a 5.5-MeV analysis threshold is 1.49 0.14(stat) 0.17(syst) events per kton-day. Interpreted as due to a pure electron flavor flux with a B neutrino spectrum, this corresponds to a spectrum integrated flux of 2.77 0.26(stat) 0.32(syst) 10 cms. The analysis threshold is driven by Tl present in the liquid scintillator, and the main source of systematic uncertainty is due to background from cosmogenic Be. The measured rate is consistent with existing measurements and with standard solar model predictions which include matter-enhanced neutrino oscillation.
- Received 8 June 2011
DOI:https://doi.org/10.1103/PhysRevC.84.035804
©2011 American Physical Society