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From: "Sir Charles W. Shults III"
Subject: Re: eer
X-Newsreader: Microsoft Outlook Express 6.00.2600.0000
Date: Wed, 30 Oct 2002 02:54:50 GMT
NNTP-Posting-Date: Tue, 29 Oct 2002 21:54:50 EST
Organization: RoadRunner - Central Florida
There are at least six distinct forms of radiation that I can think of off
the top of my head.
Alpha radiation is ionized helium nuclei- two protons and two neutrons.
Beta is electron or positron radiation, produced through weak decay in the
Gamma is highly energetic photons, of x-ray energy or higher. In fact, some
gamma is just x-rays, but it is emitted from a nucleus rather than a electron
slamming to a halt.
Neutrons can also be a form of radiation. They are massive, neutral, and
extremely penetrating. The best measurement of their half life when not
confined to a nucleus is about 614 seconds (10.3 minutes). Inside a nucleus,
they freely exchange quarks with other nucleons and cannot break down as easily.
Neutrino radiation also exists but is pretty inconsequential, since
neutrinos really barely interact with anything at all. Many billions of
neutrinos pass through each square centimeter of your body every second, many
from the sun and the rest from the stars.
Cosmic radiation is the ionized nuclei of atoms that have been accelerated
to nearly lightspeed.
That pretty much rounds out the six distinct forms of radiation.
There are secondary and tertiary showers from cosmic ray impacts, including
such debris as pions, muons, and other meson particles. Some muon showers can
reach the Earth's surface and much of the debris from cosmic radiation is what
creates carbon-14, tritium, and other radioisotopes that are naturally a part of
the background we live in. You might call this a secondary cosmic radiation
shower, and it is exotic enough to qualify as a distinct form, so I might have
to amend the list to seven forms.
Cerenkov radiation is really a bluish light emitted with particles are shot
through a medium at a speed greater than light can pass through that particular
medium. It isn't any different from any other photon radiation except in how it
is created, so it does not count as a distinct form of radiation in this
context. Make no mistake, they are NOT traveling faster than light. They are
only traveling faster than light can normally propagate through that particular
material. Refractive index in glass and other materials is due to the fact that
photons are absorbed and then re-emitted as they pass through the material, thus
"slowing" them down. Lightspeed is still lightspeed, and the limit for signal
Plain hydrogen and deuterium are not radioactive- they are extremely stable.
Tritium is radioactive and typically breaks down to either deuterium or
What is important about which isotope is doing the emitting is this- some
are very soluble, have moderate length half-lives, and can cause a great deal of
damage. We would prefer to deal with materials with either very short
half-lives (because they burn themselves out very quickly and are no threat in a
range of from nanoseconds to 6 months) or very long lived isotopes. If it has a
half life in the 4 billion year range (like uranium-238) then it is simple
enough to get a little distance between it and yourself and things are fine.
Here is a very good link showing the decay process of U-238 and its daughter
My robotics, space and CGI web page - http://home.cfl.rr.com/aichip
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