2019, Shchegolev, O. B., Alekseenko, V. V., Stepanov, V. I., Yanin, Y. V., Stenkin, Y. V., Стенькин, Юрий Васильевич

© 2019, Allerton Press, Inc.Abstract: The mass composition of primary cosmic rays remains an unresolved problem of physics in the region of energies above the knee. Results from different experiments are contradictory in assessments of the mean mass number and its variation as the primary energy grows. The PRISMA project is designed to study the energy spectrum and mass composition of cosmic rays at energies of 1015–1017 eV. The project is based on a detector capable of simultaneously detecting the electromagnetic and hadron components of a shower. The results are presented from measurements with the PRISMA-YBJ prototype located at 4300 m a.s.l., made over 3.5 years of operation. A new way of estimating the average mass composition from the electron/neutron ratio is tested.

2020, Alekseenko, V. V., Dzhappuev, D. D., Kuleshov, D. A., Kudjaev, A. U., Stenkin, Y. V., Стенькин, Юрий Васильевич

© 2020 Elsevier LtdSome unexpected sporadic increases of an environmental radioactive background have been recorded at mountain level at Baksan Neutrino Observatory (BNO, 1700 m above sea level) using electron-neutron detectors (en-detectors), which could be explained by radioactive aerosol enhancements. The large area inorganic scintillator en-detectors developed for cosmic ray study are continuously monitoring environmental thermal neutron fluxes at various geophysical conditions. Application of the pulse shape discrimination method allows us to select and separately measure both thermal neutrons and radioactive beta-decay nuclides being products of radon decays in air (mostly Rn-222 and Rn-220). There are two en-detector setups running now at BNO, one deep underground while another one at surface. Both installations had recorded some strange sporadic increases of radioactive nuclides in air. In this paper, we present results and the most probable explanation of the significant increases joint by radioactive aerosols production but caused by different reasons: Baksan river floods or nearby underground experiment with powerful Cr-51 radioactive source.

2019, Alekseenko, V., Cai, Z., Cao, Z., Cattaneo, C., Stenkin, Y., Yanin, Y., Стенькин, Юрий Васильевич

© 2019 Elsevier LtdSome new results were obtained by the array of EN-detectors (Electron and Neutron detectors) developed in the frame of the PRISMA (PRImary Spectrum Measurement Array) project for Extensive Air Showers detection. Our EN-detectors running both on the Earth surface and underground are continuously measuring the environmental thermal neutron flux. Neutrons are partially produced by radioactive gas radon and its daughter decays through (α,n)-reactions in soil close to the detectors. Then neutrons thermalize in media and, being in equilibrium with it, they are sensitive to many geo-dynamic phenomena including earthquakes. In this work the EN-detectors were measuring the variations of an environmental neutron flux in Tibet (30.11 N, 90.53 E, 4300 m a.s.l) at a distance of ∼600 km from the collision zone of the Asian-Indian plates subduction zone (Nepal region). We have observed some anomalies in the dynamics of the neutron flux around the time of the catastrophic earthquakes of magnitude M = 7.8 happened in Gorkha (Nepal) on 25.04.2015 followed by a series of aftershocks of M > 6. The use of nuclear physics methods can provide novel results in geophysics and this work demonstrates the sensitivity of the environmental thermal neutron flux to changes in tense-deformed crust conditions caused by earthquakes with epicentral distances greater than 500 km.

2021, Mannocchi, G., Trinchero, G., Yashin, I. I., Amelchakov, M. B., Astapov, I. I., Barbashina, N. S., Bogdanov, A. G., Bogdanov, F. A., Borog, V. V., Chiavassa, A., Dmitrieva, A. N., Gromushkin, D. M., Khokhlov, S. S., Kindin, V. V., Kokoulin, R. P., Kompaniets, K. G., Konovalova, A. Y., Kovylyaeva, A. A., Mishutina, Y. N., Ovchinnikov, V. V., Petrukhin, A. A., Shulzhenko, I. A., Shutenko, V. V., Stenkin, Y. V., Vorobyev, V. S., Yurin, K. O., Yurina, E. A., Zadeba, E. A., Яшин, Игорь Иванович, Амельчаков, Михаил Борисович, Астапов, Иван Иванович, Барбашина, Наталья Сергеевна, Богданов, Алексей Георгиевич, Борог, Владимир Викторович, Дмитриева, Анна Николаевна, Громушкин, Дмитрий Михайлович, Хохлов, Семен Сергеевич, Киндин, Виктор Владимирович, Кокоулин, Ростислав Павлович, Компаниец, Константин Георгиевич, Коновалова, Алена Юрьевна, Мишутина, Юлия Николаевна, Овчинников, Вячеслав Васильевич, Петрухин, Анатолий Афанасьевич, Шульженко, Иван Андреевич, Шутенко, Виктор Викторович, Стенькин, Юрий Васильевич, Воробьев, Владислав Станиславович, Юрина, Екатерина Александровна, Задеба, Егор Александрович

© 2021 IOP Publishing Ltd and Sissa Medialab.The Experimental Complex (EC) NEVOD includes a number of detectors used to carry out basic research of cosmic rays (CR) and their interactions in the energy range 1011-1019 eV and applied research of the heliosphere, magnetosphere and atmosphere of the Earth by the muonography method which is based on the analysis of spatial-angular variations of the muon flux generated by primary CR particles with energies of 10

2019, Gromushkin, D. M., Bogdanov, F. A., Bouchama, L., Bulan, A. V., Izhbulyakova, Z. T., Khokhlov, S. S., Stenkin, Y. V., Yurin, K. O., Громушкин, Дмитрий Михайлович, Хохлов, Семен Сергеевич, Стенькин, Юрий Васильевич

© 2019, Pleiades Publishing, Ltd.Two installations that allow to detect the EAS hadron component in a continuous mode, the Cherenkov water calorimeter (CWC) NEVOD and PRISMA-32 are operated in MEPhI. The comparison of the characteristics of EAS simultaneously registered by CWC NEVOD and PRISMA-32 are presented. Groups of events with different positions of the shower axis are considered.

2020, Shchegolev, O. B., Bogdanov, F. A., Izhbulyakova, Z. T., Gromushkin, D. M., Stenkin, Y. V., Громушкин, Дмитрий Михайлович, Стенькин, Юрий Васильевич

© 2020, Pleiades Publishing, Ltd.Abstract: PRISMA-32 (PRImary Spectrum Measurement Array) is working since 2012 in the Scientific & Educational Center NEVOD (NRNU ‘‘MEPhI’’, Moscow). Array area is ͠500 m2. PRISMA-32 consists of 32 specially developed electron–neutron detectors capable to measure simultaneously electronic and hadronic components of the extensive air showers with energies above 1014 eV. This feature is very important because hadronic component is a ‘‘skeleton’’ of the shower, and one can use measurements of hadron number along with simulations to recalculate primary energy spectrum independently or/and together with commonly used EAS size. Detailed Monte-Carlo simulation with CORSIKA and GEANT4 was performed and dependence of hadronic number on primary energy was obtained. Experimental data were processed and analyzed. Primary energy spectrum was recalculated from neutron number spectrum and it is in agreement with some other experiments at energies above 1016 eV. The results of the analysis are presented.

2019, Stenkin, Y. V., Стенькин, Юрий Васильевич

© 2019, Pleiades Publishing, Ltd.Primary cosmic ray energy spectrum around and above 1 PeV is of great interest due to its non-power-law behavior (“knee”) in PeV region found many years ago using the indirect EAS (Extensive Air Shower) method. The method is based on secondary particles measuring on Earth’s surface under a thick atmosphere. Traditionally, people use detectors sensitive to ionization produced mostly by secondary electromagnetic component and therefore any found changes in EAS size spectrum correspond to secondary components, which have to be recalculated to primary spectrum. Recently some new “knees” were claimed by high altitude experiments: at ∼45 TeV for all-particle spectrum (HAWC), for primary protons and helium: at ∼400 TeV (Tibet ASγ) and at ∼700 TeV (ARGO-YBJ) thus widening the “knee” region from ∼0.045 to 5 PeV. The natural explanation of such a strange spectrum behavior in a wide energy range could be found in the EAS phenomenological approach to the knee problem.

2019, Mannocchi, G., Trinchero, G., Amelchakov, M. B., Barbashina, N. S., Bogdanov, A. G., Gromushkin, D. M., Zadeba, E. A., Kindin, V. V., Kokoulin, R. P., Kompaniets, K. G., Chiavassa, A., Likiy, O. I., Petrukhin, A. A., Stenkin, Y. V., Khokhlov, S. S., Shulzhenko, I. A., Shutenko, V. V., Yurin, K. O., Yashin, I. I., Амельчаков, Михаил Борисович, Барбашина, Наталья Сергеевна, Богданов, Алексей Георгиевич, Громушкин, Дмитрий Михайлович, Задеба, Егор Александрович, Киндин, Виктор Владимирович, Кокоулин, Ростислав Павлович, Компаниец, Константин Георгиевич, Петрухин, Анатолий Афанасьевич, Стенькин, Юрий Васильевич, Хохлов, Семен Сергеевич, Шульженко, Иван Андреевич, Шутенко, Виктор Викторович, Яшин, Игорь Иванович

© 2019, Allerton Press, Inc.Abstract: The NEVOD experimental complex was created at MEPhI. It includes several facilities for studying the electron–photon, muon, and hadron components of the EAS in the energy range of 1 PeV to 1 EeV. This work presents the first results for two months of the joint operation of five facilities (NEVOD-EAS, CWD, CTS, PRISMA-32, and DECOR). The problems of synchronizing the facilities and selecting joint events are considered. The experimental data of these facilities are analyzed for different components of the EAS in overlapping energy ranges.

2020, Alekseenko, V. V., Igoshin, A. V., Kuleshov, D. A., Levochkin, K. R., Stenkin, Y. V., Стенькин, Юрий Васильевич

© 2020, Pleiades Publishing, Inc.Abstract: The gamma-ray background problem is known to be acute in any low-background underground experiment. The variations of this background depend on many parameters and should be taken into account when interpreting the results of experiments combined under the term “underground physics”. This paper is devoted to studying the long-term variations of the gamma-ray background in an underground laboratory with a scintillation detector based on a CsI crystal. Our studies have revealed a new effect in underground physics—a delayed nonlinear pumping effect for the gamma-ray background in an underground room that can lead to a significant rise of this background at an anomalously low atmospheric pressure.

2019, Alekseenko, V. V., Cai, Z., Cao, Z., Cui, S., Stenkin, Y. V., Стенькин, Юрий Васильевич

© 2019, Allerton Press, Inc.Abstract: Interesting results are obtained using a setup with electron-neutron detectors (EN-detectors) developed for the PRISMA (PRImary Spectrum Measuring Array) project to study extensive atmospheric showers. A small installation of four EN-detectors (PRISMA-YBJ) has been in operation for three and a half years on the Earth’s surface in Tibet, 4300 m above sea level, constantly measuring the natural flux of thermal neutrons. Neutrons are produced in soil during (α, n)-reactions with naturally radioactive α-particles, mainly from the decay of radon and daughter heavy nuclides. The neutrons are thermalized in the medium and, once in equilibrium with it, become sensitive to its state. They then can indicate many geophysical processes in the crust, including earthquakes. Results illustrating the sensitivity of EN-detectors to earthquakes are considered.