The Reactor Experiment for Neutrino Oscillation (RENO) is a short baseline reactor neutrino oscillation experiment in South Korea. The experiment was designed to either measure or set a limit on the neutrino mixing matrix parameter θ13, a parameter responsible for oscillations of electron neutrinos into other neutrino flavours. RENO has two identical detectors, placed at distances of 294 m and 1383 m, that observe electron antineutrinos produced by six reactors at the Hanbit Nuclear Power Plant (the old name: the Yeonggwang Nuclear Power Plant) in Korea.
Each detector consists of 16.5 t of gadolinium-doped liquid scintillator (LAB), surrounded by an additional 450 tons of buffer, veto, and shielding liquids.[1]: 6
On 3 April 2012, with some corrections on 8 April, the RENO collaboration announced a 4.9σ observation of θ13 ≠ 0, with
This measurement confirmed a similar result announced by the Daya Bay Experiment three weeks before and is consistent with earlier, but less significant results by T2K, MINOS and Double Chooz.
RENO released updated results[4] in December 2013, confirming θ13 ≠ 0 with a significance of 6.3σ:
In 2014, RENO announced the observation of an unexpectedly large number of neutrinos with an energy of 5±1 MeV.[5]: 14–15 This has since been confirmed by the Daya Bay and Double Chooz experiments,[1]: 14–17 and the cause remains an outstanding puzzle.
Expansion plans, referred to as RENO-50, will add a third medium-baseline detector at a distance of 47 km. This distance is better for observing neutrino oscillations, but requires a much larger detector due to the smaller neutrino flux. The location, near Dongshin University, has a 450 m high mountain (Mt. Guemseong), which will provide 900 m.w.e. shielding for the detector. If funded, this will contain 18000 t of scintillator,[1]: 31 surrounded by 15000 photomultiplier tubes.