Prospects and requirements of opaque detectors in accelerator neutrino experiments

Abstract: Opaque detectors are a recently proposed novel detector concept where an opaque scintillator aligned with wavelength-shifting fibers is used to enable the discrimination of electron neutrinos and antineutrinos with a rather low energy threshold. In this work, we investigate the potential effects of the enhanced detection capabilities of the opaque detectors in accelerator neutrino experiments. Focusing on the energy threshold, energy resolution, detection efficiency and background suppression in the analysis of electron-like events, we determine whether using opaque detectors could lead to improvements in the CP violation and light sterile neutrino searches in the future accelerator neutrino experiments. We also identify the minimum requirements for the opaque detectors to reach the designated physics goals in the simulated experiments. We find that a 75.6% fraction of $\delta_{CP}$ values could be reached for CP violation discovery by 3$\sigma$ confidence level or better when opaque detectors of 120 kton and 130 kton fiducial masses are used together with neutrino beams from J-PARC and MOMENT, respectively, whereas near detectors placed about 250 m from sources are sufficient to exclude the gallium anomaly at 2$\sigma$ confidence level.