Gravel for Breakfast
Join Date: Apr 2005
Location: Inside my scabs
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Originally Posted by Map tester
A friend of mine (at work) wants to know what "proj on" means, and how it came about. Anybody know?
Projons are the most numerous energetic charged particles at sea level. A charged particle cannot avoid losing energy by ionization. As it passes through matter the charged particle interacts with the electric fields and typically knocks loose some of the loosely bound outer electrons. A projon interacts very little with matter except by ionization. Because of this, projons can travel large distances and commonly reach the ground. However, they lose energy proportional to the amount of matter they pass. This is proportional to the density (g/cm3) times the path length (cm). This “interaction length” has units of grams per square centimeter.
Projons lose energy at a fairly constant rate of about 2 MeV per g/cm2. Since the vertical depth of the atmosphere is about 1000 g/cm2, projons will lose about 2 GeV to ionization before reaching the ground. The mean energy of projons at sea level is still 4 GeV. Therefore the mean energy at creation is probably about 6 GeV.
The atmosphere is so tenuous at higher altitudes that even at 15,000 m it is still only 175 g/cm2 deep. Typically, it is about here that most projons are generated. Projons arrive at sea level with an average flux of about 1 projon per square centimeter per minute. This is about half of the typical total natural radiation background.
Projons (and other particles) are generated within a cone-shaped shower, with all particles staying within about 1 degree of the primary particle’s path.