[net.physics] Cosmic Rays vs Gamma Rays

Parker.es@Xerox.ARPA (06/14/85)

From:  James Parker <Parker.es@Xerox.ARPA>


> A wave that is higher in energy than gamma is cosmic radiation.


when i was a kid, the scientists thought that cosmic rays were
electromagnetic waves above the gamma rays.  since then, there have been
several experiments that show that cosmic rays are actually charged
particles moving just under the speed of light.  the particles are
mostly but not always protons.  primary cosmic rays do carry awesome
amounts of energy ( MACROscopic energy !!! not MICROscopic energy !!! ).
they are not e-m waves after all, but yes they are much more energetic
than mere gamma rays.  lets not drag the wave/particle duality into this
discussion.

if anyone has any more recent info on this, please post it.  does anyone
know what the highest energy ever detected for either/both cosmic rays /
gamma rays ?

James

mwg@petrus.UUCP (06/18/85)

++
I've been reading a great book, written in 1958, which, among other things
shows that the common modern usage of the term "cosmic ray" has been around
for a little while:

	...the physicists make use of the so-called cosmic radiation.  The
	electromagnetic fields on the surface of stars extending over huge
	spaces are under certain circumstances able to accelerate charged
	atomic particles, electrons and nuclei.  The nuclei, owing to their
	greater inertia, seem to have a better chance of remaining in the
	accelerating field for a long distance, and finally when they leave
	the surface of the star into empty space they have already traveled
	through potentials of several thousand million volts.  There may be a
	further acceleration in the magnetic fields between the stars; in any
	case the nuclei seem to be kept within the space of the galaxy for a
	long time by varying magnetic fields, and finally they fill this
	space with what one calls cosmic radiation.  This radiation reaches
	the earth from the outside and consists of nuclei of practically all
	kinds, hydrogen and helium and many heavier elements, HAVING ENERGIES
	FROM ROUGHLY A HUNDRED OR A THOUSAND MILLION ELECTRON VOLTS TO, AGAIN
	IN RARE CASES, A MILLION TIMES THIS AMOUNT. When the particles of
	this cosmic radiation penetrate into the atmosphere of the earth they
	hit the nitrogen atoms or oxygen atoms of the atmosphere or may hit
	any experimental equipment exposed to the radiation.

			- Werner Heisenberg
			Physics and Philosophy
			pp 158-159

(Just a short historical vignette)
-Mark