N. L. Grigorov

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.

Advanced Thin Ionization Calorimeter (ATIC) balloon experiment: expected performance

An advanced thin ionization calorimeter (ATIC) will be used to investigate the charge composition and energy spectra of ultrahigh energy primary cosmic rays in a series of long- duration balloon flights. While obtaining new high priority scientific results, this balloon payload can also serve as a proof of concept for a BGO calorimeter-based instrument on the International Space Station. The ATIC technical details are presented in a companion paper at this conference. Here we discuss the expected performance of the instrument based on a GEANT code developed for simulating nuclear- electromagnetic cascades initiated by protons. For simulations of helium and heavy nuclei, a nucleus-nucleus interaction event generator LUCIAE was linked to the GEANT based program. Using these models, the design of the ATIC detector system has been optimized by simulating the instrument response to particles of different charges over the energy range to be covered. Results of these simulations are presented and discussed.

Advanced thin ionization calorimeter to measure ultrahigh energy cosmic rays

Abstract An Advanced Thin Ionization Calorimeter (ATIC) will be used to investigate the charge composition and energy spectra of primary cosmic rays over the energy range from about 10 10 to >10 14 eV in a series of long-duration balloon flights. The totally active BGO calorimeter, 22 radiation length thick, will measure the electromagnetic energy ensuing from nuclear interactions in a one interaction length thick carbon target. Trajectory information will be obtained from the location of the cascade axis in the BGO calorimeter and in the segmented scintillator layers of the upstream carbon target. The highly segmented charge module comprised of scintillator strips, a silicon matrix, and a Cherenkov array will minimize the effect of backscattered particles on primary charge measurements. While obtaining new high priority scientific results, the ATIC balloon payload can also serve as a proof of concept, or engineering model, for a BGO calorimeter-based instrument on the International Space Station. We examine the added advantage of locating such an experiment for long durations on a platform such as the Space Station.

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.

From Balloons to Space Stations

In this paper the authors present the results obtained by academician D.V. Skobeltzyn’s school in high-altitude cosmic-ray observations.

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.

uclear interactions of very-high energy with large energy transfer into neutral pions

SummaryThe experimental data were obtained using an apparatus of an area of 10 m2 installed at Mt. Aragats (3200 m above sea level). The apparatus contained emulsion plates and ionization chambers. Nuclear interactions in which a large fraction of the primary energy is transferred to neutral pions have been observed.RiassuntoI dati sperimentali sono stati ottenuti usando un’apparecchiatura della superficie di 10 m2 collocato sul monte Aragts (3200 m sul livello del mare). L’apparecchiatura conteneva lastre di emulsioni e camere di ionizzazione. Sono state osservate interazioni nucleari in cui una larga parte dell’energia primaria è trasferita a pioni neutri.

Possible Use of the Earth's Magnetic Field for Determination of the Electric Charge Sign of Cosmic Ray Particles with a Magnetic Rigidity of 103 GV and Above

We consider a variant of the use of the Earths magnetic field, which allows one to separate particles with different electric charge at a magnetic rigidity of 103 GV and above by applying advanced experimental technology.