Search for sterile neutrinos in the neutrino-4 experiment

Serebrov, A. P.; Ivochkin, V. G.; Samoilov, R. M.; Fomin, A. K.; Polyushkin, A. O.; Zinov’ev, V. G.; Neustroev, P.; Golovtsov, V.; Chernyi, A. V.; Zherebtsov, O. M.; Martemyanov, V. P.; Tarasenkov, V. G.; Aleshin, V. I.; Петелин, А. Л.; Izhutov, A. L.; Tuzov, A. A.; Sazontov, S. A.; Ryazanov, D. K.; Gromov, M. O.; Афанасьев, В. В.; Zaitsev, M. E.; Chaikovskii, M. E.

doi:10.1134/s0021364017060121

Cited by 5 publications

(3 citation statements)

References 7 publications

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“…Unfortunately, a research reactor beam hall usually has quite a large background of neutrons and gamma quanta, which makes it difficult to carry out low background experiments. Due to some peculiar characteristics of its construction, reactor SM-3 provides the most favorable conditions to search for neutrino oscillations at short distances [4,5]. However, SM-3 reactor, as well as other research reactors, is located on the Earth surface, hence, cosmic background is the major difficulty in considered experiment.…”

Section: Introductionmentioning

confidence: 99%

First Observation of the Oscillation Effect in the Neutrino-4 Experiment on the Search for the Sterile Neutrino

et al. 2019

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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.

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Section: Introductionmentioning

confidence: 99%

First Observation of the Oscillation Effect in the Neutrino-4 Experiment on the Search for the Sterile Neutrino

et al. 2019

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“…A possible interpretation of these deficits is the existence of oscillation effects induced by a light sterile neutrino state [7]. In recent years many experiments have been proposed and constructed in order to test the light sterile neutrino hypothesis as the origin of the RAA [8][9][10][11][12][13], and have also revealed a significant distortion in the ν e energy spectrum around 5 MeV [14][15][16][17]. First hints suggest that this distortion is correlated with the reactor power [16] and might be associated with the 235 U fuel [18].…”

Section: Introductionmentioning

confidence: 99%

Development of a quality assurance process for the SoLid experiment

et al. 2019

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A : The SoLid experiment has been designed to search for an oscillation pattern induced by a light sterile neutrino state, utilising the BR2 reactor of SCK•CEN, in Belgium.The detector leverages a new hybrid technology, utilising two distinct scintillators in a cubic array, creating a highly segmented detector volume. A combination of 5 cm cubic polyvinyltoluene cells, with 6 LiF:ZnS(Ag) sheets on two faces of each cube, facilitate reconstruction of the neutrino signals. Whilst the high granularity provides a powerful toolset to discriminate backgrounds; by itself the segmentation also represents a challenge in terms of homogeneity and calibration, for a consistent detector response. The search for this light sterile neutrino implies a sensitivity to distortions of around O(10)% in the energy spectrum of reactor ν e . Hence, a very good neutron detection efficiency, light yield and homogeneous detector response are critical for data validation. The minimal requirements for the SoLid physics program are a light yield and a neutron detection efficiency larger than 40 PA/MeV/cube and 50 % respectively. In order to guarantee these minimal requirements, the collaboration developed a rigorous quality assurance process for all 12800 cubic cells of the detector. To carry out the quality assurance process, an automated calibration system called CALIPSO was designed and constructed. CALIPSO provides precise, automatic placement of radioactive sources in front of each cube of a given detector plane (16×16 cubes). A combination of 22 Na, 252 Cf and AmBe gamma and neutron sources were used by CALIPSO during the quality assurance process. Initially, the scanning identified defective components allowing for repair during initial construction of the SoLid detector. Secondly, a full analysis of the calibration data revealed initial estimations for the light yield of over 60 PA/MeV and neutron reconstruction efficiency of 68%, validating the SoLid physics requirements.

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“…The Neutrino-4 experiment started in 2014, at first on a model, then on a full-scale detector and, for the first time in the world, has provided measurement data on dependence of the reactor antineutrinos flux on the distance within 6 -12 meters [17][18][19][20]. Attempts to suppress the background of fast neutrons by means of sectioning the detector has given the required result.…”

Section: Conclusion On the Current Experimental Resultsmentioning

confidence: 99%

Status of Experiment NEUTRINO-4 Search for Sterile Neutrino

Serebrov

Ivochkin

Samoilov

et al. 2017

J. Phys.: Conf. Ser.

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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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Search for sterile neutrinos in the neutrino-4 experiment

Cited by 5 publications

References 7 publications

First Observation of the Oscillation Effect in the Neutrino-4 Experiment on the Search for the Sterile Neutrino

First Observation of the Oscillation Effect in the Neutrino-4 Experiment on the Search for the Sterile Neutrino

Development of a quality assurance process for the SoLid experiment

Status of Experiment NEUTRINO-4 Search for Sterile Neutrino

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