On the measurement of solar neutrino oscillation parameters with KamLAND

AbstractA new reactor power plant Shika-2, with a power of approximately 4 GW and at a distance of about 88 km from the KamLAND detector is scheduled to start operating in March 2006. We study the impact of the ν̄e flux from this reactor on the sensitivity of the KamLAND experiment to the solar neutrino oscillation parameters. We present results on prospective determination of Δm2⊙ and sin2θ⊙ using the combined data from KamLAND and the solar neutrino experiments, including the effect of the Shika-2 contribution to the KamLAND signal and the latest data from the salt enriched phase of the SNO experiment. We find that contrary to the expectations, the addition of the Shika-2 reactor flux does not improve the sin2θ⊙ sensitivity of KamLAND, while the ambiguity in Δm2⊙ measurement may even increase, as a result of the averaging effect between Kashiwazaki and the Shika-2 reactor contributions to the KamLAND signal