Unambiguous determination of the neutrino mass hierarchy using reactor neutrinos

Abstract

Determination of the neutrino mass hierarchy in a reactor neutrino experiment at the medium baseline is discussed. Observation of the interference effects between the Ám 2 31 and Ám 2 32 oscillations enables a relative measurement independent of the knowledge of the absolute mass-squared difference. With a 20 kton liquid scintillator detector of the 3%= ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi E ðMeVÞ p energy resolution, the Daya Bay II experiment at a baseline of $50 km from reactors of total thermal power 36 GW can determine the mass hierarchy at a confidence level of Á 2 MH $ ð10 Ä 12Þ (3 Ä 3:5) in six years after taking into account the real spatial distribution of reactor cores. We show that the unknown residual energy nonlinearity of the liquid scintillator detector has limited impact on the sensitivity due to the self-calibration of small oscillation peaks. Furthermore, an extra increase of Á 2 MH ' 4ð9Þ can be obtained, by including the precise measurement of the effective mass-squared difference Ám 2 of expected relative error 1.5% (1%) from ongoing long-baseline muon neutrino disappearance experiments. The sensitivities from the interference and from absolute measurements can be cross-checked. When combining these two, the mass hierarchy can be determined at a confidence level of Á 2 MH $ ð15 Ä 20Þ (4) in six years.

A novel approach to study atmospheric neutrino oscillation

“…The first could be achieved with a medium baseline reactor experiment [8][9][10][11][12][13][14][15][16][17][18][19][20][21] and long baseline accelerator experiments [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37]44] could measure all three of them. Atmospheric neutrino experiments could offer alternative ways to accomplish the same.…”

Neutrino physics with accelerator driven subcritical reactors

“…Thus, unlike JUNO [19], the detector can be cylindrical, the PMT coverage can be less than 50% and the scintillator purity does not need to exceed that in present day experiments. Also, as 80% of the events are at energies above 30 MeV and so well above the spallation isotope backgrounds, the detectors do not need to be as deep as JUNO.…”

Shedding light on LMA-dark solar neutrino solution by medium baseline reactor experiments: JUNO and RENO-50

“…JUNO will be located at a distance of 52 km far from Yangjiang and Taishan reactor complexes with a combined power of 36 GW [11]. JUNO will also receive neutrino flux from the existing Daya Bay and planned Huizhou reactors respectively JHEP07 (2014) located 215 km and 265 km far from it.…”

“…Determining the neutrino mass hierarchy (i.e., normal vs inverted) and precision measurement of the solar mixing parameters θ 12 and ∆m 2 21 are the prime goals of these experiments [9][10][11][12][13][14][15][16][17] (see also [18][19][20][21][22][23][24]). Recently, we have shown that the data from these two experiments can also be employed to probe the superlight sterile neutrino scenario [25].…”