Future Reactor Experiments

Abstract

The measurement of the neutrino mixing angle $\theta_{13}$ opens a gateway for the next generation experiments to measure the neutrino mass hierarchy and the leptonic CP-violating phase. Future reactor experiments will focus on mass hierarchy determination and the precision measurement of mixing parameters. Mass hierarchy can be determined from the disappearance of reactor electron antineutrinos based on the interference effect of two separated oscillation modes. Relative and absolute measurement techniques have been explored. A proposed experiment JUNO, with a 20 kton liquid scintillator detector of $3%/$$\sqrt{E(MeV)}$ energy resolution, $\sim$ 53 km far from reactors of $\sim$ 36 GW total thermal power, can reach to a sensitivity of $\Delta\chi^{2}>16$ considering the spread of reactor cores and uncertainties of the detector response. Three of mixing parameters are expected to be measured to better than 1% precision. There are multiple detector options for JUNO under investigation. The technical challenges are new type of PMTs with high efficiency and highly transparent liquid scintillator. Funding has been approved from Chinese Academy of Sciences. A similar proposal was from Korea known as RENO-50. Both of them are going to start data taking around 2020.