Ch. A. Tret'yakova

The Charge State of the Anomalous Component of Cosmic Rays

The ionic charge state of anomalous cosmic-ray oxygen has been determined by comparing measurements obtained inside the magnetosphere on a series of Cosmos satellite flights with simultaneous observations outside the magnetosphere from IMP 8 and ICE. We find a mean charge state of 0.9 ^(+0.3)_(-0.2) for ~10 MeV nucleon^(-1) anomalous oxygen, consistent with the model of Fisk, Kozlovsky, & Ramaty, in which the anomalous cosmic rays originate from the neutral component of the local interstellar medium. This same approach gives results consistent with a mean charge of +7 for solar energetic oxygen ions.

Evidence for trapped anomalous cosmic ray oxygen ions in the inner magnetosphere

A series of measurements of 5–30 MeV/nucleon oxygen ions made with track detector stacks on Cosmos satellites show isotropic angular distributions during solar energetic particle events. Solar-quiet times, on the other hand, have highly anisotropic distributions suggestive of a trapped-particle component. Detailed Monte Carlo simulations confirm this interpretation and allow us to measure the trapped and cosmic-ray contributions to the observed fluxes. Our data are fully consistent with anomalous cosmic-ray ions, rather than radial diffusion from the outer zone, as the source of the trapped particles.

Anomalous oxygen in the near-earth space in 1985–1991

Abstract Some experimental results are presented on the fluxes of CNO, ions with energies ranging from 4 to 20 MeV/nucleon recorded since 1984 up to now by dielectric solid track detectors on the earth-orbiting satellite “COSMOS”.

Measurements of solar heavy ions inside the earth's magnetosphere

Abstract Stacks of cellulose nitrate and cellulose triacetate plastic nuclear track detectors were exposed on a russian satellite in a low earth orbit during the solar particle events in October 1989. Extremely high fluences of solar particles with nuclear charges equal to or greater than 6 were registered. In CTA a charge identification for Z= 8–14 with a resolution of 0.5 charge units was achieved. Energy spectra and arrival directions of the detected particles were measured in both detector materials. The distribution of the arrival directions for ions in CTA shows a significant contribution of particles impinging from below the horizon.

Determining the charge states of solar energetic ions during large geomagnetic storms

We give a progress report on a new method of measuring the mean ionic charge states of solar energetic particles (SEPs) and apply this method to oxygen ions at energies of ∼10 MeV/nucleon. We compare simultaneous flux measurements inside and outside the magnetosphere to determine the geomagnetic transmission and use this result to find the corresponding mean ionic charge state. The key to this method is to determine the dependence of the geomagnetic transmission function on the mean ionic charge state of the ions. We report here the results of a new technique to calculate the geomagnetic transmission function, which attempts to account for the cutoff suppression caused by the geomagnetic activity which often accompanies SEP events.

Recent observations of anomalous cosmic rays made with solid track detectors

Abstract A few exposures of CN-85 detectors on Earth-orbiting satellites in the period 1993–1994 show evidence for the reappearance of the radiation belt from geomagnetically trapped anomalous cosmic ray ions.

Detecting Be-7 in the orbits of the COSMOS series spacecraft during solar cycle 24

Experiments to detect the radionuclide Be-7 in the orbits of the COSMOS series satellites at altitudes of 200–400 km continued in the period 2007–2012. Measurements of Be-7 radioactivity during solar proton events and quiet periods of the Sun confirm the correlation found earlier between observed Be-7 concentrations and the magnitude of the flux of energetic solar protons near the Earth.

On the possibility of existence of an additional source of anomalous cosmic rays outside the solar system

On the basis of experimental data obtained at exposure of solid-state track detectors in the magnetosphere of the Earth during solar flares and in quiet Sun periods, an estimate of possible contribution of singly charged oxygen ions to the flare particle fluxes is made. A possibility is considered of the appearance in the vicinity of the solar system of singly ionized oxygen ions generated on stars.

Anomalous cosmic ray carbon and oxygen tracks in CN-Kodak

For observation of low energy cosmic ray particles we used CN-Kodak nuclear track detectors on Cosmos satellites. In solar quiet periods during solar minima conditions the detectors registered anomalous cosmic rays (ACRs). The ACRs are characterized by flux enhancements of several elements and it is known that the carbon enhancement is small compared with that of oxygen. In all of our quiet-time exposures the relation between carbon and oxygen was extremely small (C/O ~ 0.03). But in two quiet-time periods of 14.03.96-11.06.96 and of 15.12.97-14.04.98 we have identified many tracks as carbon in a L-R diagram. As a result the observed C/O ratio appears to be more than 0.5, whereas other experiments show no evidence of enhanced flux of carbon during these periods. The reason for the unexpected response of CN-Kodak is discussed.

The energy spectra of anomalous oxygen at the time of two successive solar minima

Abstract The energy spectra of anomalous oxygen have been determined from nuclear track detectors exposed aboard the Earth-orbiting satellites and altitudes ranging from ∼250–400 km in two consecutive solar minimum periods of 1986–1987 and 1994–1995 with opposite polarity of the solar magnetic field. A comparison of the spectra shows no contradiction to current drift models.