We report Neutrino-4 experiment results of measurements of reactor antineutrinos flux and spectrum dependence on the distance in range 6-12 meters from the center of the reactor core. The fit of experimental dependence with the law 1 L 2 ⁄ , where L is the distance from the reactor center, gave satisfactory result with goodness of fit 81%. However, we discovered that the experimental neutrino spectrum is different from the calculated one. Using experimental spectrum, we performed the model independent analysis of restrictions on oscillation parameters ∆m 14 2 and sin 2 2 14 . The results of this analysis exclude area of reactor and gallium anomaly at CL more than 99.7% (> 3 ) for values ∆m 14 2 < 3eV 2 and sin 2 2θ 14 > 0.1 However, we observed an oscillation effect at CL 2.8 in vicinity of ∆m 14 2 ≈ 7.34eV 2 and sin 2 2θ 14 ≈ 0.39. The method of coherent addition of results of measurements, which allows us to directly observe the effect of oscillations, is proposed. The analysis of that effect is presented. In general, it seems that the effect predicted in gallium and reactor experiments is confirmed but at sufficiently large value of ∆m 14 2 . Future prospects of the experiment are discussed.
The results of measurements performed using UCN storing method are in good agreement. The latest most accurate measurements of the neutron decay asymmetry and neutron lifetime measurements by storage method are in agreement within the Standard Model. However, there is a significant discrepancy at 3.6σ (1% of decay probability) level with beam method experiment. This article discusses the possible causes of discrepancy in the measurements of the neutron lifetime with beam method experiment. The most probable cause, apparently, is the loss of protons in beam method experiment during storage in a magnetic trap due to charge exchange collisions of protons with the residual gas. The proton becomes neutral and leaves the trap, which leads to a decrease in the number of registered protons, i.e. to a decrease in the probability of neutron decay or to an increase in the measured neutron lifetime.
The experiment "Neutrino-4" started in 2014 on a model, then it was continued on a full-scale detector, and now, has provided the measurement result on dependence of the flux and spectrum of reactor antineutrinos on the distance of 6 -12 meters from the center of the reactor. One of the main problems is the correlated background from fast neutrons caused by space radiation. Attempts to suppress the background of fast neutrons by sectioning the detector have given some result. The relation of signal/background has improved up to 0.6. As a result, measurements of the difference in the counting rate of neutrino-like events (reactor ON-reactor OFF) have been obtained as dependence on distance from the reactor center. The fit of experimental dependence with the law 2 1/ L give satisfactory result.The goodness of that fit is 81%. However, there was discovered experimental neutrino spectrum difference from calculated one. With achieved accuracy this difference does not change with distance. Therefore it cannot be interpreted as oscillations. Calculated spectrum form correction for experimental allow us to make proper analysis of oscillation parameters 2 14 m and 2 14 sin (2 ) limitations. Result of this analysis is exclusion of reactor and gallium anomalies area with 95% CL. Experiment future perspectives are discussed.
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