arXiv subjects

M. E. Chaikovskii

Publications and source records attributed to M. E. Chaikovskii.

11 recordsLinked to original sources

arXiv2023

The result of the Neutrino-4 experiment, sterile neutrinos and dark matter, the fourth neutrino and the Hubble constant

A brief analysis of the result of the Neutrino-4 experiment and the results of other experiments on the search for a sterile neutrino is presented. It is noted that a joint analysis of the results of the Neutrino-4 experiment and the data of the GALLEX, SAGE and BEST experiments confirms the parameters of neutrino oscillations declared by the Neutrino-4 experiment ($Δm^2_{14} = 7.3\text{eV}^2$ and $\sin^{2}2θ_{14}\approx 0.36$) and increases the confidence level to $5.8σ$. An estimate of the contribution of sterile neutrinos with these parameters to the energy density of the Universe is made. It amounted to 5.3%. It is discussed that the extension of the neutrino model by introducing two more heavy sterile neutrinos in accordance with the number of types of active neutrinos will make it possible to explain the large-scale structure of the Universe and bring the contribution of sterile neutrinos to the dark matter of the Universe to the level of 27%. Possible contradictions between the measured sterile neutrino parameters and cosmological constraints are analyzed. It is shown that, based on modern astrophysical data, it is impossible to draw a definite conclusion in favor of the model of three or four neutrinos. It is noted that the introduction of the fourth neutrino removes the Hubble tension problem without contradictions with cosmic microwave background observed by the Planck collaboration. The influence of lepton asymmetry on the comparison of models of three or four neutrinos is considered. An estimate was made for the upper limit of the lepton asymmetry $L_e< 0.02$. The possibility of the appearance of lepton asymmetry due to CP violation during oscillations into sterile neutrinos is discussed.

hep-ph↗

arXiv2023

The Result of the Neutrino-4 Experiment and the Cosmological Constraints on the Sterile Neutrino

We present a short discussion of the Neutrino-4 experimental results and the results of other experiments searching for the sterile neutrino. We estimated the contribution of the sterile neutrino with parameters $Δm^2_{14} = 7.3\text{eV}^2$ and $\sin^2 2θ_{14} = 0.36$ obtained in the Neutrino-4 experiment to the energy density of the Universe. We address the contradiction between the measured sterile neutrino parameters and the constraints on the sterile neutrino from cosmology. With this article, we want to draw attention to the problem of the contradiction between experiment and theory, in order to inspire the search for theoretical models that include a sterile neutrino with mass in the region of several eV, and to the necessity to sufficiently increase the precision of the experiment.

hep-ph↗

arXiv2022

Analysis of the result of the Neutrino-4 experiment in conjunction with other experiments on the search for sterile neutrinos within the framework of the 3 + 1 neutrino model

The correspondence of the results obtained in the Neutrino-4 experiment with the results of the NEOS, DANSS, STEREO, PROSPECT experiments at reactors, the MiniBooNE, LSND, MicroBoone experiments at accelerators, the IceCube experiment and the BEST experiment with a ${}^{51}\text{Cr}$ neutrino source is analyzed. The agreement between the results of the Neutrino-4 experiment, the BEST experiment and the gallium anomaly on mixing angel is discussed. The disagreement between the results of the above-mentioned direct experiments with the results of the reactor anomaly, as well as with the limitations from solar and cosmological data, is discussed. It is shown that the results of the above-mentioned direct experiments on the search for sterile neutrinos and IceCube experiment do not contradict the Neutrino-4 experiment within the framework of the 3+1 neutrino model at the available experimental accuracy. The sterile neutrino parameters from the Neutrino-4 and BEST experiments make it possible to estimate the sterile neutrino mass $m_4 = (2.70 \pm 0.22)\text{eV}$ and the effective mass of the electron neutrino $m_{4ν_e} = (0.82 \pm 0.21)\text{eV}$. The matrix with absolute values of the 3 + 1 neutrino model mixing parameters and the mixing scheme are presented.

hep-ex↗

arXiv2021

Experiment Neutrino-4 search for sterile neutrino and results of measurements

The experiment Neutrino-4 had started in 2014 with a detector model and then was continued with a full-scale detector in 2016 - 2021. In this article we describe all steps of preparatory work on this experiment. We present all results of the Neutrino-4 experiment with increased statistical accuracy provided to date. The experimental setup is constructed to measure the flux and spectrum of the reactor antineutrinos as a function of distance to the center of the active zone of the SM-3 reactor (Dimitrovgrad, Russia) in the range of 6 - 12 meters. Using all the collected data, we performed a model-independent analysis to determine the oscillation parameters $Δm_{14}^2$ and $\sin^22θ_{14}$. The method of coherent summation of measurement results allows to directly demonstrate the oscillation effect. We present the analysis of possible systematic errors and the MC model of the experiment, which considers the possibility of the effect manifestation at the present precision level. As a result of the analysis, we can conclude that at currently available statistical accuracy we observe the oscillations at the $2.9σ$ level with parameters $Δm_{14}^2=(7.3\pm0.13_{st}\pm1.16_{sys})\text{eV}^2 = (7.3\pm1.17)\text{eV}^2$ and $\sin^22θ_{14}= 0.36\pm0.12_{stat}(2.9σ)$. Monte Carlo based statistical analysis gave estimation of confidence level at $2.7σ$. We plan to improve the currently working experimental setup and create a completely new setup in order to increase the accuracy of the experiment by 3 times. We also provide a brief analysis of the general experimental situation in the search for sterile neutrinos.

hep-ex↗

arXiv2021

Search for explanation of the neutron lifetime anomaly

All results of the neutron lifetime measurements performed in the last 20 years with the UCN storage method are in a good agreement. These results are consistent with the latest most accurate measurements of the neutron decay asymmetry within the Standard Model. However, there is a significant discrepancy at $3.6σ$ (1% of the decay probability) level between the averaged result of the storage method experiments and the most accurate measurements performed with the beam method. This article addresses the possible causes of such discrepancy. We focused on finding the spectrum of possible systematic corrections in the beam experiment. Four separate sources of the systematic errors which had not been properly addressed in articles dedicated to the beam technique were considered. Two of those sources are related with the motion of protons in an electromagnetic field and the elastic scattering by the residual gas. The third error concerns proton loss in the dead layer of the detector. It is shown the corresponding correction requires a more detailed analysis than that given in the papers describing the beam measurement method. The fourth source of the systematic error is the charge exchange process on the residual gas. The influence of that process was neglected in the beam method experiments. We present arguments that careful analysis of this issue is necessary since the proposed proton losses correction decreases the measured lifetime. For the problem of proton charge exchange on a residual gas, the spectrum of possible corrections is investigated. It is shown that for an accurate calculation of the correction, it is necessary to directly measure the concentration and composition of the residual gas inside the proton trap. The analysis reveals that even presence of only $H_2$ molecules can lead to the significant correction which is the most probable explanation of the neutron anomaly.

nucl-ex↗

arXiv2020

The possible explanation of neutron lifetime beam anomaly

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.

nucl-ex↗

arXiv2020

The first observation of effect of oscillation in Neutrino-4 experiment on search for sterile neutrino (continuation)

We present the results of the Neutrino-4 experiment on search for a sterile neutrino. The experiment has been carried out on the SM-3 reactor having a compact active zone of $42\times42\times35\textrm{cm}^3$ and operating on the highly enriched uranium-235 at 90 MW thermal power. We report the results of the Neutrino-4 experiment of measurements of reactor antineutrino flux and spectrum dependence on the distance in the range 6-12 meters from the center of the reactor core. Using the measured spectrum and the distance dependence of antineutrino flux, we performed the model independent analysis of restrictions on the oscillation parameters $Δm^2_{14}$ and $\sin^2 2θ_{14}$. The method of coherent addition of results of measurements is proposed. It allows us to directly observe the effect of oscillations. We observed the oscillation effect at CL $3.5σ$ in the vicinity of $Δm^2_{14} \approx 7.26\textrm{eV}^2$ and $\sin^2 2θ_{14} \approx 0.38$. Combining the result of the Neutrino-4 experiment and the result of the gallium anomaly effect we obtained value $\sin^2 2θ_{14} \approx 0.35 \pm 0.07 (5σ)$. The analysis of systematics effects is presented. Comparison with results of other experiments is presented. Future prospect of the experiment is discussed. It is necessary to notice that obtained values $\sin^2 2θ_{14} \approx 0.35 \pm 0.07 (5σ)$ and $Δm^2_{14} \approx (7.3 \pm 0.7)\textrm{eV}^2$ allow make assessment on the mass of a neutrino: $m_β \approx 0.8\textrm{eV}$.

hep-ex↗

arXiv2018

Conservation laws for classical particles in Anti-de Sitter-Beltrami space

In this paper we consider the conservation laws for classical particles in $AdS_4$. At first we parameterize a geodesic line and construct conserved quantities with analog of five dimensional Minkowski space-time $M^{(2,3)}$. Consequently we change $AdS_4$ space to AdS-Beltrami space-time and write conserved quantities in the Beltrami coordinates. Finally we take a limit for small velocity $\dot{x}\ll c$ and we get the conserved quantities in Lorentz-Fock space-time. And finally we give out the energy of the nonrelativistic noncosmological particle under the cosmological limit.

gr-qc↗

arXiv2018

Experiment Neutrino-4 and restrictions for sterile neutrino

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 effect/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 $1/L^2$ 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 $Δm^2_{14}$ and $\sin^2(2θ)$ limitations. Result of this analysis is exclusion of reactor and gallium anomalies area with 95% CL. Experiment future perspectives are discussed.

physics.ins-det↗

arXiv2017

Experiment NEUTRINO-4 Search for Sterile Neutrino

In order to carry out research in the field of possible existence of a sterile neutrino the laboratory based on SM-3 reactor (Dimitrovgrad, Russia) was created to search for oscillations of reactor antineutrino. A moveable detector, protected with passive shielding from outer radiation, can be set at distance range 6 to 12 meters from the reactor core. Measurements of antineutrino flux at such short distances from the reactor core are carried out with moveable detector for the first time. The main difficulties of the measurements caused by cosmic background and it heavily decreases the precision of measurements. We present the analysis of measurements at small distances together with the data obtained in measurements at long distances in order to obtain parameters of sterile neutrino.

physics.ins-det↗

arXiv2016

Neutrino-4 experiment on search for sterile neutrino with multi-section model of detector

In order to carry out research in the field of possible existence of sterile neutrino the laboratory based on SM-3 reactor (Dimitrovgrad, Russia) was created to search for oscillations of reactor antineutrino. The prototype of a multi-section neutrino detector with liquid scintillator volume of 350 l was installed in the middle of 2015. It is a moveable inside the passive shielding detector, which can be set at distance range from 6 to 11 meters from the reactor core. Measurements of antineutrino flux at such small distances from the reactor core carried out with movable detector for the first time. The measurements carried out with detector prototype demonstrated a possibility of measuring a reactor antineutrino flux in difficult conditions of cosmic background at Earth surface.

physics.ins-det↗