Monitoring of the time and spatial distribution of neutron-flux spectral density outside the Russian segment of the International Space Station based on data from the BTN-Neutron space experiment

• Published in: Cosmic research 2017-03, Vol.55 (2), p.110-123
• Main Authors: Litvak, M. L., Mitrofanov, I. G., Nuzhdin, I. O., Vostrukhin, A. V., Golovin, D. V., Kozyrev, A. S., Malakhov, A. V., Mokrousov, M. I., Sanin, A. B., Tretyakov, V. I., Fedosov, F. S.
• Format: Article
• Language: English
• Subjects: Anomalies; Astronomy; Astrophysics and Astroparticles; Astrophysics and Cosmology; Cosmic rays; Data acquisition; Data analysis; Density; Dosage; Earth surface; Equator; Equatorial regions; Fast neutrons; Fluctuations; Galactic cosmic rays; International Space Station; Modulation; Multinational space ventures; Neutron flux; Neutrons; Periodic variations; Physics; Physics and Astronomy; Solar cycle; Solar cycles; Space Exploration and Astronautics; Space Sciences (including Extraterrestrial Physics; Space stations; Spatial distribution; Spectra
• ISSN: 0010-9525; 1608-3075
• DOI: 10.1134/S001095251702006X

Results of measurements of neutron-flux spectral density in the vicinity of the International Space Station (ISS) based on BTN-Neutron space experimental data acquired in 2007–2014 have been presented in this paper. It has been shown that, during the flight of the ISS over different regions of the Earth’s surface, neutron flux in the energy range of 0.4 eV–15 MeV varies from 0.1 n/sm 2 /s in equatorial regions to 50 n/sm 2 /s in the South Atlantic anomaly region. The measurements were used to estimate the contribution of the neutron component to the overall exposure dose rate. The total contribution of fast neutrons is about 0.1–0.4 μ Zv/h above the equator area and more than 50 μ Zv/h above the South Atlantic anomaly region. A data analysis of BTN-Neutron data also showed that the time profile of neutron flux has long-periodic variations. It was found that, under the influence of Galactic cosmic rays (GCRs), modulation during 24th solar cycle neutron flux changed almost twofold (above high latitude regions). Maximum values of neutron flux were observed in January 2010 and minimum values were observed in January 2014.