2019, Ahdida, C., Albanese, R. M., 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

© 2019 CERN.This paper presents a fast approach to simulating muons produced in interactions of the SPS proton beams with the target of the SHiP experiment. The SHiP experiment will be able to search for new long-lived particles produced in a 400 GeV/c SPS proton beam dump and which travel distances between fifty metres and tens of kilometers. The SHiP detector needs to operate under ultra-low background conditions and requires large simulated samples of muon induced background processes. Through the use of Generative Adversarial Networks it is possible to emulate the simulation of the interaction of 400 GeV/c proton beams with the SHiP target, an otherwise computationally intensive process. For the simulation requirements of the SHiP experiment, generative networks are capable of approximating the full simulation of the dense fixed target, offering a speed increase by a factor of (106). To evaluate the performance of such an approach, comparisons of the distributions of reconstructed muon momenta in SHiP's spectrometer between samples using the full simulation and samples produced through generative models are presented. The methods discussed in this paper can be generalised and applied to modelling any non-discrete multi-dimensional distribution.

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.

2019, Aleksandrov, A. B., Alekseev, V. A., Bagulya, A. V., Dashkina, A. B., Grachev, V. M., Polukhina, N. G., Грачев, Виктор Михайлович, Полухина, Наталья Геннадьевна

© 2019, Allerton Press, Inc.The results of the search for tracks of heavy and superheavy nuclei of galactic cosmic rays in the charge range Z = 26 − 129, identified in olivine crystals from Maryalahti and Eagle Station meteorites are presented. The database including characteristics of 21743 tracks, obtained in the OLIMPIA experiment, is currently the largest one within the charge range under study. It includes three tracks of superheavy nuclei with charge 119−6 +10 and a minimum lifetime estimated as several tens of years, which can be considered as a direct experimental validation of the existence of natural superheavy nuclei from the “stability island”.

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, 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.

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, 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)%.

2019, Abiev, A. K., Bagulya, A. V., Chernyavsky, M. M., Dimitrienko, A. A., Grachev, V. M., Polukhina, N. G., Грачев, Виктор Михайлович, Полухина, Наталья Геннадьевна

© 2019, Pleiades Publishing, Ltd.Cosmic ray muonography is a novel technique for imaging of the internal structures of large natural and industrial objects. It exploits the capability of high energy muons from cosmic rays to penetrate large thicknesses of large subjects to be studied, in order to obtain a density map. It uses muon flux attenuation and absorption in materials of investigated objects. Nuclear emulsions are tracking detectors well suited to be employed in muonography for investigations of inner structure of large objects up to kilometers size, since emulsions have firstly an excellent angular resolution, they are compact and robust, do not require power supply. The muonography methods are applied to study one of UNESCO world heritage objects, the unusual building in the Naryn-Kala citadel hidden underground. The use of nuclear emulsions as probing radiation detectors provides for a uniquely high resolution capacity of recording instrumentation combined with the potential of modern image analysis methods giving 3D reconstruction of the internal structures of the investigated object.

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.