New Results of Measurements in the Neutrino-4 Experiment Devoted to Searches for Sterile Neutrinos

Abstract

New results of measurements of the dependences of the flux of reactor antineutrinos and their spectrum on the distance from the center of the core of the SM-3 reactor (Dimitrovgrad, Russia) in the range from 6 to 12 m are presented. Additional measurements were conducted. The volume of accumulated experimental data was increased nearly by a factor of two. A model-independent analysis was performed on the basis of all data in order to determine the oscillation parameters $\Delta m_{14}^{2}$ and $\sin^{2}2\theta_{14}$. The method of a coherent summation of measurement results makes it possible to demonstrate directly the oscillation effect. We observed the oscillation effect at a level of three standard deviations ($3.0\sigma$) in the vicinities of parameters values of $\Delta m_{14}^{2}\approx 7.25$ eV${}^{2}$ and $\sin^{2}2\theta_{14}\approx 0.26\pm 008\left({3.0}\right)\sigma$. Combining the results of the Neutrino-4 experiment with results for the gallium anomaly and for the reactor anomaly, we obtained the following value: $\sin^{2}2\theta_{14}\approx 0.19\pm 0.04(4.6\sigma)$.