(Solved): (3 10). The parameter of neutrino oscillation Xij=(mi2mj2)4EL=1.267eV2mi2mj2 ...

(3 10). The parameter of neutrino oscillation $X_{ij}=\left(m_i^2?m_j^2\right)\frac{L}{4E}=1.267\frac{m_i^2?m_j^2}{e{V}^2}\left(\frac{L}{\text{ meters }}\right)\left(\frac{MeV}{E}\right)$ optimally needs to be of the order one. "Atmospheric" muon neutrino produced by cosmic rays in atmosphere and going through Earth's radius, can oscillate into the tau-neutrino and produce $?$ lepton in the detector. Taking for difference of masses $?M_{??}?(0.05eV{)}^2$, what neutrino energy $E_{\text{opt }}$ is optimal for such oscillation experiment?