Neutrino flavour relaxation or neutrino oscillations?

We propose the new mechanism of neutrino flavour relaxation to explain the experimentally observed changes of initial neutrino flavour fluxes. The test of neutrino relaxation hypothesis is presented, using the data of modern reactor, solar and accelerator experiments. The final choice between the standard neutrino oscillations and the proposed neutrino flavour relaxation model can be done in future experiments

The Kr2Det project: Search for mass-3 state contribution |U_{e3}|^2 to the electron neutrino using a one reactor - two detector oscillation experiment at Krasnoyarsk underground site

The main physical goal of the project is to search with reactor antineutrinos for small mixing angle oscillations in the atmospheric mass parameter region around {\Delta}m^{2}_{atm} ~ 2.5 10^{-3} eV^2 in order to find the element U_{e3} of the neutrino mixing matrix or to set a new more stringent constraint (U_{e3} is the contribution of mass-3 state to the electron neutrino flavor state). To achieve this we propose a "one reactor - two detector" experiment: two identical antineutrino spectrometers with $\sim$50 ton liquid scintillator targets located at ~100 m and ~1000 m from the Krasnoyarsk underground reactor (~600 mwe). In no-oscillation case ratio of measured positron spectra of the \bar{{\nu}_e} + p \to e^{+} + n reaction is energy independent. Deviation from a constant value of this ratio is the oscillation signature. In this scheme results do not depend on the exact knowledge of the reactor power, nu_e spectra, burn up effects, target volumes and, which is important, the backgrounds can periodically be measured during reactor OFF periods. In this letter we present the Krasnoyarsk reactor site, give a schematic description of the detectors, calculate the neutrino detection rates and estimate the backgrounds. We also outline the detector monitoring and calibration procedures, which are of a key importance. We hope that systematic uncertainties will not accede 0.5% and the sensitivity U^{2}_{e3} ~4 10^{-3} (at {\Delta}m^{2} = 2.5 10^{-3} eV^2) can be achieved.Comment: Latex 2e, 9 pages and 5 ps figure