1/14/2024 0 Comments Cosmic radiationThis difference from the "outer space" balance of particles is a result of both the proton deflection and the fact that the majority of Secondary Particles released when Primary Particles collide with atoms of hydrogen and helium in the upper atmosphere are neutrons. By comparison, at sea level at the same latitudes, the particles present are nearly all muons. For a 35000 ft altitude in temperate latitudes, typical shares of ambient radiation will be neutrons (55%), electrons and positrons (20%), protons (15%), photons (5%), and muons (5%). The balance depends on altitude, latitude and the position in the solar cycle. The result of the interaction of Primary Particles with the atmosphere is a complex radiation field which has a composition very different to that further out in space. The latter is the case at high latitudes whereas at the equator, the magnetic field is perpendicular to the direction of particle motion and a much greater proportion of particles are deflected. Least deflection occurs for high energy particles and those travelling parallel to the lines of force of the magnetic field. This effect varies according to the energy state of the impacting particle and its trajectory in relation to the magnetic field. Nearer the Earth, the Primary Particles of cosmic radiation are nearly all electrically charged and many are deflected by the earth’s magnetic field. The term "Space Weather" is used to describe all these solar-caused or solar-moderated phenomena. Other types of short term and generally unpredictable solar activity can also vary the magnetic fields of both the sun and the earth and can produce major but very temporary increases in cosmic radiation at aircraft altitudes but they are infrequent and make little difference to the rates of dose accumulation. Whilst its routine effect on cosmic radiation levels is beneficial, the solar maximum is also the most likely time for the generation of Solar Particle Events (SPEs) in which solar flares or coronal mass ejections release large amounts of energy which cannot be forecast although they are short lived - hours to days in duration. This follows an 11 year activity cycle which at its maximum output, coincides with increased numbers of sunspots and serves to deflect relatively more of the galactic cosmic radiation component away from the earth with the converse also applying. Within the solar system, lower energy particles are deflected by the magnetic field of the solar wind - the stream of plasma emitted by the Sun. Galactic cosmic radiation in the local environment of the solar system consists of about 86% positively charged hydrogen nuclei (protons), 11% alpha particles (helium nuclei), 2% electrons (or beta particles) with heavy metal ions and antimatter particles called positrons making up the rest. "Cosmic Radiation" is the collective term for the ionising radiation present in the earth’s atmosphere which has originated either from the sun or from outside our solar system (galactic radiation) as Primary Particles or has been created as a result of the interaction of these primary particles with the earth’s atmosphere to create Secondary Particles. Ionising radiation is radiation which can displace charged particles, which means that molecules within the cell walls of living organisms can be disrupted. Radiation is "the transfer of energy from a source" which may be in the form of electromagnetic radiation such as gamma rays and x-rays or in the form of mobile and highly accelerated sub atomic particles.
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