2021, Agafonova, N., Alexandrov, A., Anokhina, A., Aoki, S., Polukhina, N., Полухина, Наталья Геннадьевна

The OPERA experiment was designed to discover the v(tau) appearance in a v(mu) beam, due to neutrino oscillations. The detector, located in the underground Gran Sasso Laboratory, consisted of a nuclear photographic emulsion/lead target with a mass of about 1.25 kt, complemented by electronic detectors. It was exposed from 2008 to 2012 to the CNGS beam: an almost pure v(mu) beam with a baseline of 730 km, collecting a total of 1.8 center dot 10(20) protons on target. The OPERA Collaboration eventually assessed the discovery of v(mu)-> v(tau) oscillations with a statistical significance of 6.1 sigma by observing ten v(tau) CC interaction candidates. These events have been published on the Open Data Portal at CERN. This paper provides a ydetailed description of the v(tau) data sample to make it usable by the whole community.

2020, Ahdida, C., Albanese, R., Alexandrov, A., Anokhina, A., Atkin, E., Dmitrenko, V., Etenko, A., Filippov, K., Gavrilov, G., Grachev, V., Kudenko, Y., Novikov, A., Polukhina, N., Samsonov, V., Shustov, A., Skorokhvatov, M., Smirnov, S., Teterin, P., Ulin, S., Uteshev, Z., Vlasik, K., Аткин, Эдуард Викторович, Дмитренко, Валерий Васильевич, Этенко, Александр Владимирович, Грачев, Виктор Михайлович, Куденко, Юрий Григорьевич, Полухина, Наталья Геннадьевна, Шустов, Александр Евгеньевич, Скорохватов, Михаил Дмитриевич, Смирнов, Сергей Юрьевич, Тетерин, Пётр Евгеньевич, Улин, Сергей Евгеньевич, Утешев, Зияэтдин Мухамедович, Власик, Константин Федорович

© 2020 CERN. Published by IOP Publishing Ltd on behalf of Sissa Medialab. Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.The Search for Hidden Particles (SHiP) experiment proposal at CERN demands a dedicated dipole magnet for its scattering and neutrino detector. This requires a very large volume to be uniformly magnetized at B > 1.2 T, with constraints regarding the inner instrumented volume as well as the external region, where no massive structures are allowed and only an extremely low stray field is admitted. In this paper we report the main technical challenges and the relevant design options providing a comprehensive design for the magnet of the SHiP Scattering and Neutrino Detector.

2022, Alexandrov, A. B., Vasina, S. G., Galkin, V. I., Gippius, A. A., Grachev, V. M., Kalinina, V. G., Konovalov, A. S., Konovalova, N. S., Korolev, P. S., Larionov, A. A., Managadze, A. K., Melnichenko, I. A., Okateva, N. M., Polukhina, N. G., Roganova, T. M., Sadykov, Zh. T., Starkov, N. I., Starkova, E. N., Tyukov, V. E., Chernyavsky, M. M., Shevchenko, V. I., Shchedrina, T. V., Шевченко, Владимир Игоревич, Ларионов, Алексей Александрович, Полухина, Наталья Геннадьевна

An innovative noninvasive method of muonography based on emulsion detectors has been developed. The new method enables detection of changes in the fluxes of atmospheric muons passing through the object under study and determination of the specific features of its internal structure. Owing to the use of the state-of-the-art automated scanning facilities, large-scale studies of natural and industrial objects can be carried out that require processing of large quantity of photoemulsion. A major muonography experiment, in which the internal structure of buildings and the territory of the Svyato-Troitsky Danilov Monastery had been examined, is described in detail.

2019, Alexeev, V. A., Bagulya, A. V., Volkov, A. E., Gippius, A. A., Grachev, V. M., Polukhina, N. G., Грачев, Виктор Михайлович, Полухина, Наталья Геннадьевна

This work was performed within the OLYMPIA experiment on the study of tracks of heavy and superheavy cosmic ray nuclei in olivine crystals from Marjalahti and Eagle Station pallasites. Depth distributions of the track formation rate for heavy cosmic ray nuclei in olivine crystals from pallasites of different pre-atmospheric sizes were obtained. The dependences obtained were used to analyze the data on the track density in olivine crystals from the Marjalahti pallasite. In three crystals, the track distribution with a high density gradient was detected, which indicates a complicated radiation history of the meteorite.

2021, Soe, T. N., Starkov, N. I., Polukhina, N. G., Полухина, Наталья Геннадьевна

© 2021, Pleiades Publishing, Ltd.Abstract: The dynamics of heating of a meteorite that travels through the Earth’s atmosphere is studied. The heating of its matter over the meteorite fall time is estimated by solving the heat-propagation equation. It is shown that the temperature of olivine crystals situated at a distance of 3 to 5 mm from the meteorite edge may reach 1200 to 1300C, and this may lead to the track-annealing effect. As a result, some tracks disappear, while some of them change their geometric features. This may explain an unusual shape of the charge distribution of nuclei found in olivine crystals situated near the meteorite edge.

2020, Alexandrov, A. B., Bagulya, A. V., Volkov, A. E., Gippius, A. A., Grachev, V. M., Polukhina, N. G., Грачев, Виктор Михайлович, Полухина, Наталья Геннадьевна

© 2020, Allerton Press, Inc.Abstract: A new additional aspect of the analysis of the data of the OLYMPIA experiment on the search for nuclei of heavy cosmic ray components in olivine crystals from stony—iron meteorites is presented. Two groups of crystals with different charge spectra of recorded nuclei are detected. Possible causes of this phenomenon and its effect on the final spectrum are discussed.

2022, Chernyavskiy, M. M., Gippius, A. A., Konovalova, N. S., Malinin, A. G., Okateva, N. M., Petrov, A. N., Polukhina, N. G., Shevchenko, V. I., Shchedrina, T. V., Starkova, E. N., Starkov, N. I., Шевченко, Владимир Игоревич, Полухина, Наталья Геннадьевна

IOP Publishing Ltd and Sissa Medialab.The paper describes the matching of tracks in a nuclear emulsion detector interleaved with scintillating optical fiber (SciFi) planes. This technology is planned to be used in the Scattering and Neutrino Detector (SND) of the new experiment SHiP (Search for Hidden Particles) being developed in CERN. The experiment SHiP aimed on the search of very weakly interacting particles in the poorly studied region of the particle masses below 10 GeV will be installed in a beam dump facility at the Super Proton Synchrotron (SPS). The SND detector is aimed to provide temporal and spatial analysis of the particle showers and isolated tracks to separate and reconstruct events in nuclear emulsion. SND design includes emulsion cloud chamber (ECC) and SciFi tracker. Motivation for using the combination of ECC and SciFi is to obtain the "real-time"information for the prompt and high-accuracy event analysis. The algorithm presented in the article provides a track matching accuracy not less than 50 μm with an efficiency of (89±8)%.

2021, Aleksandrov, A. B., Dashkina, A. B., Konovalova, N. S., Okat'eva, N. M., Polukhina, N. G., Полухина, Наталья Геннадьевна

Determining the nature of dark matter (DM) is one of the most important challenges of modern experimental physics. This article overviews the major arguments confirming the existence of DM, gives the latest classifications of DM particles, identifies possible candidates for their role, and discusses the most significant DM particle search experiments conducted and under development. The article mainly aims to give an idea of diverse experimental methods of and approaches to registering DM particles, as well as of the currently available results of the search for them, which open new prospects in DM studies and contribute to solving topical problems in New Physics.

2020, Agafonova, N., Aleksandrov, A., Anokhina, A., Aoki, S., Polukhina, N., Полухина, Наталья Геннадьевна

© 2020, The Author(s).An event topology with two secondary vertices compatible with the decay of short-lived particles was found in the analysis of neutrino interactions in the OPERA target. The observed topology is compatible with tau neutrino charged current (CC) interactions with charm production and neutrino neutral current (NC) interactions with cc¯ pair production. However, other processes can mimic this topology. A dedicated analysis was implemented to identify the underlying process. A Monte Carlo simulation was developed and complementary procedures were introduced in the kinematic reconstruction. A multivariate analysis technique was used to achieve an optimal separation of signal from background. Most likely, this event is a ντ CC interaction with charm production, the tau and charm particle decaying into 1 prong and 2 prongs, respectively. The significance of this observation is evaluated.

2019, Agafonova, N., Alexandrov, A., Anokhina, A., Aoki, S., Polukhina, N., Полухина, Наталья Геннадьевна

The OPERA experiment has conclusively observed the appearance of tau neutrinos in the muon neutrino CNGS beam. Exploiting the OPERA detector capabilities, it was possible to isolate high purity samples of nu(e), nu(mu), and nu(tau) charged current weak neutrino interactions, as well as neutral current weak interactions. In this paper, the full dataset is used for the first time to test the three-flavor neutrino oscillation model and to derive constraints on the existence of a light sterile neutrino within the framework of the 3 + 1 neutrino model. For the first time, tau and electron neutrino appearance channels are jointly used to test the sterile neutrino hypothesis. A significant fraction of the sterile neutrino parameter space allowed by LSND and MiniBooNE experiments is excluded at 90% C.L. In particular, the best-fit values obtained by MiniBooNE combining neutrino and antineutrino data are excluded at 3.3 sigma significance.