Abstract
All the evolution of the scientific knowledge about Cosmic Rays (CRs) in the 20 t h century leads to the following statement: Cosmic Rays constitutes a time and spatial variable flux of fully ionized energetic atoms and sub-atomic particles with specific abundances and energies that continuously permeates the solar system, reaching the Earth and producing ionization and nuclear reactions in our atmosphere. Since the primary CR flux is composed of charged particles, it is expected that any magnetic irregularity and/or turbulence affects their large scale transport and consequently its energy spectrum. Moreover, since the interaction of the CR particles with the terrestrial atmosphere produces not only atmospheric ionization, but also nuclear reactions (creating a cascade of secondary particles), it is easy to understand that near ground CR measurements (direct or indirect) may allow us to study the physical processes involved in the journey of CR particles (including the birth conditions of the lower energetic ones and the propagation of the higher energetic ones through the heliosphere) before reaching the terrestrial environment, and also along the transport of the secondary particles into the Earth's atmosphere. In this sense, considering a cosmic ray particle as a ”celestial messenger” is reasonable. Therefore, several works have been using the CR footprints found in the terrestrial surface (through the ground-based measurement of cosmogenic tracers) as a tool for solar and atmospheric studies. It is present here a discussion concerning the time evolution of the CR scientific knowledge and a brief review of the physical concepts of those celestial messengers.
Highlights
Toda a evolucao do conhecimento cientifico sobre os Raios-Cosmicos ocorrida no seculo XX nos levou a seguinte constatacao: raios cosmicos constituem um fluxo variavel no tempo e no espaco de partıculas atomicas e sub- atomicas energeticas totalmente ionizadas que permeia continuamente o sistema solar produzindo ionizacao e reacoes nucleares na atmosfera terrestre
All the evolution of the scientific knowledge about cosmic rays” (CRs) in the last century leads to the following statement: Cosmic Rays constitutes a time and spatial variable flux of fully ionized energetic atoms and sub-atomic particles with specific abundances and energies that continuously permeates the solar system, reaching the Earth and producing ionization and nuclear reactions in the terrestrial atmosphere
There is a significant excess of some nuclei in the Galactic Cosmic Rays (GCRs) flux compared with the solar system abundances
Summary
In the beginning of 20th century, the scientific community was intrigued by the discovery of the permae1306-2. All different experiments suggested that the air ionization has an altitude dependence and its causing radiation has a penetrating component. Besides those evidences, the dominant opinion about this radiation origin didn’t change so and for a decade it was attributed to radioactive materials in the Earth’s crust [1]. In the year of 1912, Domenico Pacini (in February) first considered that ”a sizeable cause of ionization exists in the atmosphere, originating from penetrating radiation, independent of the direct action of radioactive substances in the soil”, and Victor Hess (in August) demonstrated by balloon measurements that there was a new source of such radiation from above. There are still some big questions to be solved (like the astrophysical origin of the highest energy component and the turnovers in its energy spectrum) and besides the development of particle accelerators, the role of CR studies in nuclear physics is still important
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