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Results for “COSMIC RADIATION”

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At least 127 records · Page 7Linked to original sources
PubMed2004

New calculations of the atmospheric cosmic radiation field--results for neutron spectra.

The propagation of primary cosmic rays through the Earth's atmosphere and the energy spectra of the resulting secondary particles have been calculated using the Monte Carlo transport code FLUKA with several novel auxiliary methods. Solar-modulated primary cosmic ray spectra were determined through an analysis of simultaneous proton and helium measurements made on spacecraft or high-altitude balloon flights. Primary protons and helium ions are generated within the rigidity range of 0.5 GV-20 TV, uniform in cos2theta. For a given location, primaries above the effective angle-dependent geomagnetic cut-off rigidity, and re-entrant albedo protons, are transported through the atmosphere. Helium ions are initially transported using a separate transport code called HEAVY to simulate fragmentation. HEAVY interfaces with FLUKA to provide interaction starting points for each nucleon originating from a helium nucleus. Calculated cosmic ray neutron spectra and consequent dosimetric quantities for locations with a wide range of altitude (atmospheric depth) and geomagnetic cut-off are presented and compared with measurements made on a high-altitude aeroplane. Helium ion propagation using HEAVY and inclusion of re-entrant albedo protons with the incident primary spectra significantly improved the agreement of the calculated cosmic ray neutron spectra with measured spectra. These cosmic ray propagation calculations provide the basis for a new atmospheric ionising radiation (AIR) model for air-crew dosimetry, calculation of effects on microelectronics, production of cosmogenic radionuclides and other uses.

Algorithms↗
PubMed1999

Physics of cosmic radiation fields.

This paper glances at the knowledge of composition and energy spectra of galactic cosmic rays and briefly discusses the mechanism of solar modulation and of shielding against these particles by the earth's magnetic field. A short review of the properties of solar particle events is given, in which particles emitted from the sun enter the atmosphere. Particle production in the earth's atmosphere in hadronic and electromagnetic cascades is described and the altitude variations of the different particle components are investigated. Typical energy spectra in the atmosphere are presented for some types of particles.

Altitude↗
PubMedDate not supplied

[Solar cosmic radiation and the radiation hazard of space flight].

Present-day data on the spectrum of solar radiation in the source and near the Earth are discussed as applied to the radiation safety of crewmembers and electronics onboard manned and unmanned spacecraft. It is shown that the slope of the solar radiation spectrum changes (flattens) in the low energy range. Quantitative information about absolute solar radiation fluxes near the Earth is summarized in relation to the most significant flares of 1956--1978. The time-related evolution of the solar radiation spectrum in the interplanetary space is described in quantitative terms (as illustrated by the solar flare of 28 September 1961). It is indicated that the nonmonotonic energy dependence of the transport path of solar radiation in the interplanetary space should be taken into consideration. It is demonstrated that the diffusion model of propagation can be verified using solar radiation measurements in space flights.

Cosmic Radiation↗