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Xuefeng Ding
中文

JUNO · REACTOR ν̄ₑ

Neutrino oscillation

JUNO — the Jiangmen Underground Neutrino Observatory — watches electron antineutrinos from two nuclear power plants about 52.5 km away. At that baseline the survival probability carries both the slow “solar” oscillation (Δm²₂₁) and the fast “atmospheric” one (Δm²₃₁); the interference between them is what lets JUNO pin down the neutrino mass ordering. Drag the parameters and watch the curve move.

P(νˉe ⁣→ ⁣νˉe)=1−cos⁡4θ13 sin⁡22θ12 sin⁡2Δ21−sin⁡22θ13 ⁣(cos⁡2θ12 sin⁡2Δ31+sin⁡2θ12 sin⁡2Δ32)P(\bar\nu_e\!\to\!\bar\nu_e)=1-\cos^4\theta_{13}\,\sin^2 2\theta_{12}\,\sin^2\Delta_{21}-\sin^2 2\theta_{13}\!\left(\cos^2\theta_{12}\,\sin^2\Delta_{31}+\sin^2\theta_{12}\,\sin^2\Delta_{32}\right) Δij=1.267 Δmij2 [eV2]  L [m]E [MeV],Δm322=Δm312−Δm212\Delta_{ij}=1.267\,\frac{\Delta m^2_{ij}\,[\mathrm{eV}^2]\;L\,[\mathrm{m}]}{E\,[\mathrm{MeV}]},\qquad \Delta m^2_{32}=\Delta m^2_{31}-\Delta m^2_{21}
Reactor ν̄ₑ survival probability — three-flavour, vacuum.
━ normal ordering━ inverted orderingL = 52.5 km

Survival P(E)

Power |F|²

Sine (FST, imag)

Cosine (FCT, real)

▲ = PDG best-fit (click to snap). The spectra change mainly with Δm²₃₁ and the resolution; finite resolution low-pass-filters the atmospheric peak. θ₂₃, δ_CP are absent (no reactor effect).