Sunday, 30 January 2011

Visualising cosmic radiation

What types of particles are constantly passing through us?

Examine the cloud chamber and the tracks that are visible inside the chamber.

The flashing streaks are primarily the tracks of cosmic radiation arriving from outer space. The tracks of the particles become visible in the alcohol fumes of the cloud chamber. When the particles collide with the fumes, they condense into small droplets. Part of the radiation in the chamber originates from the Earth.

Cosmic radiation is comprised of high-energy particles originating from the Sun and exploded stars. Altogether 90 % of the particles are protons, 9 % are alpha particles and 1 % represent beta particles and the nuclei of heavier atoms. Cosmic radiation is only one part of the ionizing radiation which human beings get from nature. Its amount is minor in relation to the other radiation that we get, such as the radioactive radiation from radon gas in the ground or the radiation from x-ray machinery used for medical purposes. The magnetic field and atmosphere of the Earth almost entirely prevents any cosmic radiation from reaching the Earth’s surface.

Flight personnel may receive up to 10 times more cosmic radiation than the rest of the population. Its health impacts are, however, quite minimal, even though it may be the most significant source of radiation for flight personnel.

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