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Plastic radiation shield.

Better than Lead for use in space.
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The image that I would like to start you with is.
A tick fog, during the day. Light comes at you from all sides, but there is a lot less of it. And its cold, because the water droplets have absorbed all of the infra red.

Lead as very little stopping power for neutrons, and its stopping power for electromagnetic radiation falls as the frequency increases. At energy s above 1.5 Me V air has more stopping power.

The idea consists of a plastic matrix containing a fine powder.

The plastic for the matrix will be one that has a lot of Hydrogen in it, to give it some stopping power for neutrons.

The fine powder scatters the radiation both by; diffraction as it passes by the particles edge. And reflection as it strikes the particle at a low angle. With enough of these interactions the radiation gets scattered in all directions, including back the way it came. Analogous to light in the fog.

The fine powder is made of separate powder of each of the metallic elements each particle is individually coated with plastic, before they are blended and added to the matrix. Each metal will absorb radiation in the same way as Lead would, usually less effectively, but also each element has its own absorption edges. An absorption edge is a part of the spectrum at which an element absorbs EM radiation very strongly. This energy can be dissipated as heat, or re-radiated at a frequency slightly lower than the absorbing frequency, as a K, L, or M shell emission This emission need not be in the same direction as the original radiation.

Element absorbs emits
Bi 0.173 0.165
Os 0.167 0.201
Yb 0.202 0.241
Gd 0.246 0.293
Pr 0.295 0.348 e.t.c

the lighter an element, the more likely it is to lose energy as heat.

As well as a radiation shield this material will also serve as a structural component, and thermal insulation. And will be used on the SCCS to be posted later.

j paul, Aug 28 2011

Starlite http://en.wikipedia.org/wiki/Starlite
[xaviergisz, Aug 29 2011]

[link]






       Well, yes, why not?   

       (One question - are your figures for Bismuth correct? It seems to emit at a shorter wavelength than it absorbs.)
MaxwellBuchanan, Aug 28 2011
  

       Problems:
1: If some particles re-radiate the EM energy as heat, you might find your plastic melting...
2: On the other hand, space is cold, so your plastic/metal composite might become brittle. Micrometeorites might become an issue in that case.
I'm no expert in materials science or radiation, so feel free to correct me if I'm wrong.
neutrinos_shadow, Aug 29 2011
  

       Have you considered just using aerogel, or implanting the plastics inside of aerogel? It has been used to trap micrometeorites, and it causes diffraction of sunlight.
ye_river_xiv, Aug 29 2011
  
      
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