The NuEYE Telescope

Sterile neutrino search

In the neutrino sector, the SM of particle physics must be extended to explain the observed neutrino oscillations, which imply nonzero neutrino masses. Further extensions include one or more sterile neutrinos (νs) to explain experimental anomalies observed over the past few decades. Since the finding of LSND, there have been lots of reactor, neutron spallation facility, or accelerator based experiments confirming or denying the sterile neutrino interpretation of LSND finding. Having a consistent picture in current sterile neutrino search experiments is somewhat tricky at present, In particular, it is increasingly important to carefully examine the BEST result, which uses the radiochemical method. We propose to use a high-intensity neutrinos from a dedicated accelerator or radioactive source to sort out issues with sterile neutrinos. Here we briefly describe both approaches.

- High intensity neutrinos with accelerator (IsoDAR)

A US group is proposing a high-intensity neutrino beam from a dedicated high-current accelerator (IsoDAR). We are in close contact with IsoDAR group in hosting the IsoDAR accelerator in Yemilab. The IsoDAR sensitivity to the sterile neutrino can be found from PHYSICAL REVIEW D 105, 052009 (2022) [arXiv:2111.09480].

- High intensity radioactive source

Very intense does of radioactive sources such as 41Cr or 144Ce can be used to produce high rate neutrino flux for the NuEYE telescope. The 41Cr source has been already used in several experiments and the SOX project from Borexino considered 144Ce. Our finding on the senstivity of sterile neutrino search can be seen in the below figure with our calculation on IsoDAR sensitivity included:

Reactor neutrino oscillation parameter

There are four nuclear power plants in Korea and among them, the Hanul reactor complex, the closest to Yemilab, is about 65 km away, which corresponds to the first minimum of the survival probability of anti-electron neutrino. This gives the NuEYE detector would be one of the best locations to confirm neutrino oscillations in the three-flavor paradigm. Our expected sensitivities are ∆m^2_21 = (7.51 ± 0.06) × 10−5 eV^2 and sin2 ^2θ_12 = 0.848 ± 0.010 (statistical uncertainties only) for a five-year run and our fit result is shown below:

Solar neutrino

The Borexino experiment paved the way to the Solar neutrino experiment. One of the most crucial components in this subject is the radio-purification of the LS. Assuming similar radio-purification level as in the Borexino experiment, we attempt to explore the possibility of looking at "up-turn" of the electron-neutrino survival probability at the boundary between vacuum and matter region as in the figure below based on figure-year running of the NuEYE experiment. Note that this is a conservative estimation and there are rooms to improve in future.

Neutrinoless double beta decay

The NuEYE detector can be turned into a decent 0νββ search detector that is competitive with existing and other planned experiments when it is loaded with an appropriate ββ-decay. Possible candidate isotopes include Tin-124 (124Sn) or 130Te. We plan to have a long-term R&D for ββ-candidates, and loading methods into LS, in order to reach the half-life time sensitivity of order 10^28 years, at the last stage of the NuEYE project.

Search for new physics beyond Standard Model of particle physics

The NuEYE detector is also senitive to various new physics scenarios of physics beyond Standard Model. The large sample from (anti-)neutrino decays can be used for a precise measurement of sin^2 θ_W and to test the consistency of weak couplings measured in ν_e-e and νμ_-e scattering data. The elastic scattering sample can also serve as a sensitive probe of nonstandard neutrino interactions. More on Ref. PHYSICAL REVIEW D 89, 072010 (2014) [arXiv:1307.5081].