Re: Hole in a box

From: John Clark (
Date: Sat Feb 16 2002 - 11:19:06 MST

 Mike Lorrey <> Wrote:

>What PERCENT of xrays are absorbed for a given thickness/density
>of matter?

It depends on what type of matter, elements with a high atomic number are
much better at absorbing X rays. It also depends on the intensity of the X rays,
the stronger the beam the lower the percentage of X ray photons that will make
it through. This is because the more X rays you hit something with the more
it will become ionized and the more it is ionized the more likely it is to absorb
X rays. Even at a hundred million degrees an element like Uranium would still
hang on to a few electrons and such a highly ionizes substance would powerfully
absorb X rays because the remaining electrons would have a huge number of
possible excitation states. It's true that if Uranium lost ALL its 92 electrons the
transparency would go up because then the X rays could only react to matter with
the much weaker Thomson scattering effect, but you'd need temperatures in the
billions not millions for that to happed, the last electron would be extremely difficult
to remove. By the way, I still don't understand why you don't want to use the ready
made super hot gas around a Black Hole directly in a heat engine.

        John K Clark

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