V. A. Dergachev

The high-energy heavy-particle fluences in the orbits of manned space stations

The results are presented of measurements high-energy particles in a customary manned space station orbit (a 350-450-km altitude, a 51.6 degrees inclination; Salyut-6 and 7, MIR). The particles were recorded by the chambers composed of the Lavsan (polyethyleneterephtalate) solid-state nuclear track detector layers mounted outside a spacecraft for 1-3 years. A high resolution has been attained in the charge and energy spectra of 30-200 MeV/n Fe group particles. The results of measuring the particle fluxes in the space station orbits are used to restore the initial particle energy spectra in terms of the models that describe the galactic and solar cosmic rays and their penetration to the Earths magnetosphere. The analysis demonstrates a high effectiveness of the described methods when applied to quite a number of space physics problems.

Fluxes of GCR and SCR iron nuclei in the international space station orbit

The anticipated flux of iron nuclei and ions in the energy interval 26–168 MeV/nucleon in the orbit of the international space station (ISS) during the exposure of the PLATAN-M dielectric track detector from January 26, 2002, to August 3, 2004, has been estimated. The calculation is based on the data obtained using the SIS spectrometer onboard the ACE space station and the last version of the model describing the penetration of charged particles into the Earth’s magnetosphere. The time variations in the GCR iron nuclei intensity in the ISS orbit during solar cycle 23 have been obtained using the data of the PLATAN-4 and PLATAN-5 earlier experiments onboard the Mir space station.

Low energy heavy nuclei in Lavsan chamber on the salyut-7 space station in 1984–1985

Abstract Energy spectra of subiron (Scue5f8Cr) and iron nuclei in the range 40–210 MeV/n have been measured and subiron to iron abundance ratio was determined from a study of a polyethyleneterephthalate (Lavsan) detector exposed in 1984–1985 during a year on the Salyut-7 space station. The ratio measured is ∼0.9 in the energy range 170–210 MeV/n that confirms previous data. The value differs from that 0.4-0.5 measured in interplanetary space. The ratio is ∼0.45 in the range 40–110 MeV/n. The peculiarities observed are discussed.

Energy spectra of low-energy solar iron particles measured in the orbit of the international space station in the period 2002–2004

The energy spectrum of iron is measured over the range of 30–150 MeV/nucleon using the PLATAN-M chamber consisting of solid-state track detectors mounted on the external surface of the International Space Station (ISS) in the period 2002–2004. The spectra of solar and galactic cosmic rays (SCRs and GCRs) are compared to the data from the SIS instrument on board the ACE spacecraft, transformed to the ISS orbit. Compared to the SIS data, the energy resolution of the PLATAN-M spectrum is twice better and the spread of experimental points is 50% lower.

Results of measuring the fluxes of solar energetic particles and methods of their interpretation

Reliability and credibility of the results of measurements of the fluxes of protons and heavy ions of solar energetic particles, carried out with various experimental methods, are studied, as well as the methods of description of obtained data with various model functions of energy spectra. We analyze the results of measuring the fluxes of heavy ions of solar cosmic rays with the use of solid-state track detectors in the experiments Astro (April 1981, Salyut-6 spacecraft) and Platan-3 (1988–1989, Mir orbital station) and compare them with the results of experiments VLET and CRT made onboard the IMP-8 satellite. Special emphasis is made on the analysis of results obtained with instruments SIS and ULEIS (ACE), and of results of measuring the fluxes of helium ions by the instrument EPEAD on GOES satellites. We also discuss the problem of fitting experimental data about SCR fluxes by different functions of energy (momentum, velocity) of particles. Such an approximation is a basis for interpreting the results of measurements. Numerous systematic errors are revealed that are typical for the results of measurements of the fluxes of SCR particles, performed with different instruments onboard Earth-orbiting satellites and other space vehicles.

Spectra of Fe ions in powerful SCR events

Large solar cosmic ray (SCR) events are registered by PLATAN equipment in September–October 1989 aboard the MIR orbital station and in October–November 2003 aboard the International Space Station (ISS). The energy spectra of Fe ions in the energy intervals of 5–200 MeV/nucleon (1989) and 25–90 MeV/nucleon (2003) are measured. Spectra for SCR events of 1989 and 2003 are approximated with high accuracy by the power law function of energy. The SCR events of 1989 greatly exceed those of 2003 in the fluence of Fe particles. High enrichment of the elemental composition of the SCR events 2003 with Fe ions is observed.

Changes in the geomagnetic dipole moment over last 12 thousand years, the concentration of cosmogenic isotopes, and optimization of 14C exchange parameters between atmosphere and ocean

The long-term variations in the production rate of 10Be and 14C in the Earth’s atmosphere during the last 10 thousand years caused by the geomagnetic-field effect have been investigated. It is shown that the difference in the correlation coefficient between the production rate of 10Be and 14C and variations in the dipole magnetic moment of the Earth is due to the lack of knowledge about the 14C exchange parameter for the carbon reservoir. The optimal parameters of the reservoir model of radiocarbon exchange, averaged over 10 thousand years, are found.

200-year variations in cosmic rays modulated by solar activity and their climatic response

Manifestation of the 200-year solar cycle (de Vries cycle) in climatic changes (summer temperatures) has been investigated by analyzing the radial growth of long-lived (800–1200 yr) Juniperus turkestanica trees in Central Asia. Quasi-two-hundred-year variations in the radial growth of trees have been revealed, which correlate well (correlation coefficient reaches 0.94) with similar solar activity variations (Δ14C).

Investigation of heavy cosmic-ray nuclei by solid-state track detectors on orbiting platforms

Results are presented from investigations of Fe-group nuclei in galactic and solar cosmic rays in the energy ranges 30–210 MeV/n and 7–210 MeV/n in various phases of the solar cycles. Spectra of Fe particles have been obtained with high energy resolution as a result of exposing PLATAN chambers, made up of layers of a polyethyelene terephthalate solid-state track detector, for between one and three years on the Salyut-6, Salyut-7, and Mir space stations, orbiting at an inclination of 51.6° to the plane of the equator and at an altitude of 350–400 km. Measurements were made of the energy spectra of Fe particles from a unique event, the series of solar flares of September 29 and October 19–29, 1989, which is the most powerful of those recorded and measured over the entire history of cosmic ray research. A modern model of particle penetration inside the Earth’s magnetosphere, developed at the Institute of Nuclear Physics at Moscow State University, is used to compare the measured spectrum with measurements made using the solid-state track detector in the HIIS experiment on the LDEF station, and with extramagnetospheric measurements made using electronic equipment on the IMP-8 satellite and the Galileo space station. It is shown that the solid-state track detector technique has advantages for obtaining the characteristics of the energy spectrum.