Персона:
Литвинович, Евгений Александрович

Научные группы

Научная группа

Физика нейтрино и астрочастиц (Кафедра №40)

Организационные подразделения

Организационная единица

Цель ИЯФиТ и стратегия развития - создание и развитие научно-образовательного центра мирового уровня в области ядерной физики и технологий, радиационного материаловедения, физики элементарных частиц, астрофизики и космофизики.

Фамилия

Литвинович

Имя

Евгений Александрович

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Теперь показываю 1 - 10 из 30

Только метаданные
Improved measurement of B-8 solar neutrinos with 1.5 kt . y of Borexino exposure
(2020) Agostini, M.; Altenmuller, K.; Appel, S.; Atroshchenko, V.; Litvinovich, E.; Machulin, I.; Skorokhvatov, M.; Литвинович, Евгений Александрович; Мачулин, Игорь Николаевич; Скорохватов, Михаил Дмитриевич
We report on an improved measurement of the B-8 solar neutrino interaction rate with the Borexino experiment at the Laboratori Nazionali del Gran Sasso. Neutrinos are detected via their elastic scattering on electrons in a large volume of liquid scintillator. The measured rate of scattered electrons above 3 MeV of energy is 0.223(-0.016)(+0.015) (stat) (+0.006)(-0.006) (syst) cpd/100 t, which corresponds to an observed solar neutrino flux assuming no neutrino flavor conversion of Phi(ES)(8B) = 2.57(-0.18)(+0.17) (stat) (+0.07)(-0.07) (syst) x 10(6) cm(-2) s(-1). This measurement exploits the active volume of the detector in almost its entirety for the first time, and takes advantage of a reduced radioactive background following the 2011 scintillator purification campaign and of novel analysis tools providing a more precise modeling of the background. Additionally, we set a new limit on the interaction rate of solar hep neutrinos, searched via their elastic scattering on electrons as well as their neutral current-mediated inelastic scattering on carbon, C-12(nu, nu')C-12* (E-gamma = 15.1 MeV).
Только метаданные
Constraints on flavor-diagonal non-standard neutrino interactions from Borexino Phase-II
(2020) Agarwalla, S. K.; Agostini, M.; Altenmuller, K.; Appel, S.; Litvinovich, E.; Machulin, I.; Skorokhvatov, M.; Литвинович, Евгений Александрович; Мачулин, Игорь Николаевич; Скорохватов, Михаил Дмитриевич
© 2020, The Author(s).The Borexino detector measures solar neutrino fluxes via neutrino-electron elastic scattering. Observed spectra are determined by the solar-νe survival probability Pee(E), and the chiral couplings of the neutrino and electron. Some theories of physics beyond the Standard Model postulate the existence of Non-Standard Interactions (NSI’s) which modify the chiral couplings and Pee(E). In this paper, we search for such NSI’s, in particular, flavor-diagonal neutral current interactions that modify the νee and ντe couplings using Borexino Phase II data. Standard Solar Model predictions of the solar neutrino fluxes for both high- and low-metallicity assumptions are considered. No indication of new physics is found at the level of sensitivity of the detector and constraints on the parameters of the NSI’s are placed. In addition, with the same dataset the value of sin2θW is obtained with a precision comparable to that achieved in reactor antineutrino experiments [Figure not available: see fulltext.].
Только метаданные
Comprehensive geoneutrino analysis with Borexino
(2020) Agostini, M.; Altenmuller, K.; Appel, S.; Atroshchenko, V.; Litvinovich, E.; Machulin, I.; Skorokhvatov, M.; Литвинович, Евгений Александрович; Мачулин, Игорь Николаевич; Скорохватов, Михаил Дмитриевич
© 2020 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/" Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.This paper presents a comprehensive geoneutrino measurement using the Borexino detector, located at Laboratori Nazionali del Gran Sasso (LNGS) in Italy. The analysis is the result of 3262.74 days of data between December 2007 and April 2019. The paper describes improved analysis techniques and optimized data selection, which includes enlarged fiducial volume and sophisticated cosmogenic veto. The reported exposure of (1.29±0.05)×1032 protons ×year represents an increase by a factor of two over a previous Borexino analysis reported in 2015. By observing 52.6-8.6+9.4(stat)-2.1+2.7(sys) geoneutrinos (68% interval) from U238 and Th232, a geoneutrino signal of 47.0-7.7+8.4(stat)-1.9+2.4(sys) TNU with -17.2+18.3% total precision was obtained. This result assumes the same Th/U mass ratio as found in chondritic CI meteorites but compatible results were found when contributions from U238 and Th232 were both fit as free parameters. Antineutrino background from reactors is fit unconstrained and found compatible with the expectations. The null-hypothesis of observing a geoneutrino signal from the mantle is excluded at a 99.0% C.L. when exploiting detailed knowledge of the local crust near the experimental site. Measured mantle signal of 21.2-9.0+9.5(stat)-0.9+1.1(sys) TNU corresponds to the production of a radiogenic heat of 24.6-10.4+11.1 TW (68% interval) from U238 and Th232 in the mantle. Assuming 18% contribution of K40 in the mantle and 8.1-1.4+1.9 TW of total radiogenic heat of the lithosphere, the Borexino estimate of the total radiogenic heat of the Earth is 38.2-12.7+13.6 TW, which corresponds to the convective Urey ratio of 0.78-0.28+0.41. These values are compatible with different geological predictions, however there is a ∼2.4σ tension with those Earth models which predict the lowest concentration of heat-producing elements in the mantle. In addition, by constraining the number of expected reactor antineutrino events, the existence of a hypothetical georeactor at the center of the Earth having power greater than 2.4 TW is excluded at 95% C.L. Particular attention is given to the description of all analysis details which should be of interest for the next generation of geoneutrino measurements using liquid scintillator detectors.
Только метаданные
Experimental evidence of neutrinos produced in the CNO fusion cycle in the Sun
(2020) Agostini, M.; Altenmuller, K.; Appel, S.; Atroshchenko, V.; Litvinovich, E.; Machulin, I.; Nugmanov, R.; Skorokhvatov, M.; Литвинович, Евгений Александрович; Мачулин, Игорь Николаевич; Скорохватов, Михаил Дмитриевич
© 2020, The Author(s), under exclusive licence to Springer Nature Limited.For most of their existence, stars are fuelled by the fusion of hydrogen into helium. Fusion proceeds via two processes that are well understood theoretically: the proton–proton (pp) chain and the carbon–nitrogen–oxygen (CNO) cycle1,2. Neutrinos that are emitted along such fusion processes in the solar core are the only direct probe of the deep interior of the Sun. A complete spectroscopic study of neutrinos from the pp chain, which produces about 99 per cent of the solar energy, has been performed previously3; however, there has been no reported experimental evidence of the CNO cycle. Here we report the direct observation, with a high statistical significance, of neutrinos produced in the CNO cycle in the Sun. This experimental evidence was obtained using the highly radiopure, large-volume, liquid-scintillator detector of Borexino, an experiment located at the underground Laboratori Nazionali del Gran Sasso in Italy. The main experimental challenge was to identify the excess signal—only a few counts per day above the background per 100 tonnes of target—that is attributed to interactions of the CNO neutrinos. Advances in the thermal stabilization of the detector over the last five years enabled us to develop a method to constrain the rate of bismuth-210 contaminating the scintillator. In the CNO cycle, the fusion of hydrogen is catalysed by carbon, nitrogen and oxygen, and so its rate—as well as the flux of emitted CNO neutrinos—depends directly on the abundance of these elements in the solar core. This result therefore paves the way towards a direct measurement of the solar metallicity using CNO neutrinos. Our findings quantify the relative contribution of CNO fusion in the Sun to be of the order of 1 per cent; however, in massive stars, this is the dominant process of energy production. This work provides experimental evidence of the primary mechanism for the stellar conversion of hydrogen into helium in the Universe.
Только метаданные
Letter of interest for a neutrino beam from Protvino to KM3NeT/ORCA
(2019) Akindinov, V.; Anassontzis, E. G.; Anton, G.; Ardid, M.; Litvinovich, E.; Skorokhvatov, M. D.; Литвинович, Евгений Александрович; Скорохватов, Михаил Дмитриевич
The Protvino accelerator facility located in the Moscow region, Russia, is in a good position to offer a rich experimental research program in the field of neutrino physics. Of particular interest is the possibility to direct a neutrino beam from Protvino towards the KM3NeT/ORCA detector, which is currently under construction in the Mediterranean Sea 40 km offshore Toulon, France. This proposal is known as P2O. Thanks to its baseline of 2595 km, this experiment would yield an unparalleled sensitivity to matter effects in the Earth, allowing for the determination of the neutrino mass ordering with a high level of certainty after only a few years of running at a modest beam intensity of sensitivity to the leptonic CP-violating Dirac phase can be achieved. A second stage of the experiment, comprising a further intensity upgrade of the accelerator complex and a densified version of the ORCA detector (Super-ORCA), would allow for up to a 6 sigma\documentclass[12pt] resolution on the CP phase after 10 years of running with a 450 kW beam, competitive with other planned experiments. The initial composition and energy spectrum of the neutrino beam would need to be monitored by a near detector, to be constructed several hundred meters downstream from the proton beam target. The same neutrino beam and near detector set-up would also allow for neutrino-nucleus cross section measurements to be performed. A short-baseline sterile neutrino search experiment would also be possible.
Только метаданные
Search for low-energy neutrinos from astrophysical sources with Borexino
(2021) Agostini, M.; Altenmuller, K.; Appel, S.; Atroshchenko, V.; Litvinovich, E.; Machulin, I.; Skorokhvatov, M.; Литвинович, Евгений Александрович; Мачулин, Игорь Николаевич; Скорохватов, Михаил Дмитриевич
© 2020We report on searches for neutrinos and antineutrinos from astrophysical sources performed with the Borexino detector at the Laboratori Nazionali del Gran Sasso in Italy. Electron antineutrinos (ν¯e) are detected in an organic liquid scintillator through the inverse β-decay reaction. In the present work we set model-independent upper limits in the energy range 1.8–16.8 MeV on neutrino fluxes from unknown sources that improve our previous results, on average, by a factor 2.5. Using the same data set, we first obtain experimental constraints on the diffuse supernova ν¯e fluxes in the previously unexplored region below 8 MeV. A search for ν¯e in the solar neutrino flux is also presented: the presence of ν¯e would be a manifestation of a non-zero anomalous magnetic moment of the neutrino, making possible its conversion to antineutrinos in the strong magnetic field of the Sun. We obtain a limit for a solar ν¯e flux of 384 cm–2 s–1 (90% C.L.), assuming an undistorted solar 8B neutrinos energy spectrum, that corresponds to a transition probability pνe→ν¯e< 7.2 × 10–5 (90% C.L.) for Eν¯e > 1.8 MeV. At lower energies, by investigating the spectral shape of elastic scattering events, we obtain a new limit on solar 7Be-νe conversion into ν¯e of pνe→ν¯e< 0.14 (90% C.L.) at 0.862 MeV. Last, we investigate solar flares as possible neutrino sources and obtain the strongest up-to-date limits on the fluence of neutrinos of all flavor neutrino below 3–7 MeV. Assuming the neutrino flux to be proportional to the flare's intensity, we exclude an intense solar flare as the cause of the observed excess of events in run 117 of the Cl-Ar Homestake experiment.
Только метаданные
Identification of the cosmogenic 11 C background in large volumes of liquid scintillators with Borexino
(2021) Agostini, M.; Altenmuller, K.; Appel, S.; Atroshchenko, V.; Litvinovich, E.; Machulin, I.; Nugmanov, R.; Skorokhvatov, M.; Литвинович, Евгений Александрович; Мачулин, Игорь Николаевич; Скорохватов, Михаил Дмитриевич
© 2021, The Author(s).Cosmogenic radio-nuclei are an important source of background for low-energy neutrino experiments. In Borexino, cosmogenic 11C decays outnumber solar pep and CNO neutrino events by about ten to one. In order to extract the flux of these two neutrino species, a highly efficient identification of this background is mandatory. We present here the details of the most consolidated strategy, used throughout Borexino solar neutrino measurements. It hinges upon finding the space-time correlations between 11C decays, the preceding parent muons and the accompanying neutrons. This article describes the working principles and evaluates the performance of this Three-Fold Coincidence (TFC) technique in its two current implementations: a hard-cut and a likelihood-based approach. Both show stable performances throughout Borexino Phases II (2012–2016) and III (2016–2020) data sets, with a 11C tagging efficiency of ∼ 90 % and ∼ 63–66 % of the exposure surviving the tagging. We present also a novel technique that targets specifically 11C produced in high-multiplicity during major spallation events. Such 11C appear as a burst of events, whose space-time correlation can be exploited. Burst identification can be combined with the TFC to obtain about the same tagging efficiency of ∼ 90 % but with a higher fraction of the exposure surviving, in the range of ∼ 66–68 %.
Только метаданные
Improved Measurement of Solar Neutrinos from the Carbon-Nitrogen-Oxygen Cycle by Borexino and Its Implications for the Standard Solar Model
(2022) Appel, S.; Litvinovich, E.; Machulin, I.; Nugmanov, R.; Skorokhvatov, M.; Литвинович, Евгений Александрович; Мачулин, Игорь Николаевич; Скорохватов, Михаил Дмитриевич
Только метаданные
IDREAM: Industrial Detector of REactor Antineutrinos for Monitoring at Kalinin nuclear power plant
(2022) Abramov, A.; Chepurnov, A.; Etenko, A.; Litvinovich, E.; Machulin, I.; Skorokhvatov, M.; Этенко, Александр Владимирович; Литвинович, Евгений Александрович; Мачулин, Игорь Николаевич; Скорохватов, Михаил Дмитриевич
Только метаданные
Simultaneous precision spectroscopy of pp, Be 7, and pep solar neutrinos with Borexino Phase-II
(2019) Agostini, M.; Altenmuller, K.; Appel, S.; Atroshchenko, V.; Litvinovich, E.; Machulin, I.; Skorokhvatov, M.; Литвинович, Евгений Александрович; Мачулин, Игорь Николаевич; Скорохватов, Михаил Дмитриевич
© 2019 authors. Published by the American Physical Society.We present the simultaneous measurement of the interaction rates Rpp, RBe, Rpep of pp, Be7, and pep solar neutrinos performed with a global fit to the Borexino data in an extended energy range (0.19-2.93) MeV with particular attention to details of the analysis methods. This result was obtained by analyzing 1291.51 days of Borexino Phase-II data, collected after an extensive scintillator purification campaign. Using counts per day (cpd)/100 ton as unit, we find Rpp=134±10(stat)-10+6(sys), RBe=48.3±1.1(stat)-0.7+0.4(sys); and RpepHZ=2.43±0.36(stat)-0.22+0.15(sys) assuming the interaction rate RCNO of CNO-cycle (Carbon, Nitrogen, Oxigen) solar neutrinos according to the prediction of the high metallicity standard solar model, and RpepLZ=2.65±0.36(stat)-0.24+0.15(sys) according to that of the low metallicity model. An upper limit RCNO<8.1 cpd/100 ton (95% C.L.) is obtained by setting in the fit a constraint on the ratio Rpp/Rpep (47.7±0.8 cpd/100 ton or 47.5±0.8 cpd/100 ton according to the high or low metallicity hypothesis).