Lightweight Radiation-proof Fabric?

kramer writes "New Scientist is reporting the creation of a lighweight radiation-proof fabric called Demron. Demron is being touted by its inventors as comparable to lead shielding at a fraction of the weight. Could be very useful for any future interplanetary space missions where the amount of radiation absorbed by the crew is a significant concern."

Comments

Re:Imaginary Particles?

[Ann Coulter]

The electron clouds give an "illusion" of large atoms when viewed with gamma or X-rays. These electron configurations are just as effective for providing radiation obstruction as any heavy element such as lead or bismuth. Illusions can beget real effects if used correctly.

Volume

[moc.tfosorcimgllib]

I'm sure you meant the fabric takes up less volume, as I would hope that weight is not an issue in space.

Testing

[justanyone]

It seems reasonable that that gamma radiation (high energy photons) could be intercepted by a 'cloud of electrons' in the polymer in this material.

However, high energy neutrons would not interact with the electrons due to their high velocities. The relativistic effect of width/length contraction applies to these neutrons. This was the fundamental problem of early fission reactors - they had to moderate (reduce the speed of) the neutrons in order for them to appear big enough to interact with a nucleus. An electron is 1,836 times less massive than a proton. Thus you'd need 1836 electrons to equal one proton-with of neutron blocking power. I doubt they have that many electrons in the polymer's cloud!

However, any material that more effectively screens high energy photons is a welcome material. It would also be highly useful in creating X-Ray and Gamma-ray telescopes, methinks! NASA, you listening?

The article should have gone into which radiation types besides Alpha particles that it would block (Alphas I think are just Hydrogen nucleii - or is it Helium...).

Cosmic ray shielding would be useful on the ISS as well, but it would not stop relativistic particles, and it might break down under repeated insults of high energy collisions occurring regularly in space.

Any nuclear engineers out there who can comment better? go Navy?!?

Re:Testing

[Imabug]

anybody who's studied radiation interactions with matter will tell you that for gamma/X rays, it's not the density (g/cm^3) of the material but the electron density (electrons/cm^3) that determines the attenuation properties of a material. Generally, metals with a higher atomic number (Z) have more electrons, so they usually have better attenuation properties.

As it turns out, sometimes you can pack lighter weight nuclei close enough together that you get a similar electron density to metals (or even higher sometimes). this is probably what they've done with this 'polymer'. Althogh on a mailing list I'm on, someone mentioned that the material was just fabric that had been soaked in a barium solution and dried. Whether that was true or not was never establised though.

There is one incorrect statement in the article though.

"The helium nuclei that make up alpha radiation have so little energy that almost any physical barrier can stop them."

Alpha particles can be emitted with extremely high energies, upwards of 10 MeV. What makes alpha particles so non-penetrating is their charge. Their +2 charge causes them to interact very strongly with neighbouring electrons, which causes them to lose energy quickly. That's also the reason why there isn't any special shielding necessary for alpha particles. Most alpha particles will be stopped in the dead layer of your skin, and therefore pose little external hazard. What makes alpha particles dangerous is if they become internalized (inhaled or ingested). The fact they lose energy quickly means that energy is transferred to whatever material it happens to collied with, causing much damage in the process.

Question,

[3-State Bit]

The researchers say it's comparable to lead shielding in terms of shielding radiation, but this does not quite address an important concern. Is it like lead shielding only with respect to nuclear radiation? Or x-rays and such as well?

I'm only asking because I'm trying to figure out whether Superman can see through it. Any help is appreciated.

-Lex.

Does it protect against Scammer Rays?

[0x69]

Low-energy alpha & beta are easily blocked with century-old technology. Their explanation of how they block X and gamma sounds like smoke & mirrors to me.

BTW, '0.00% of gamma gets through' may be worse than nothing, since the secondary shower (from whatever the gamma ray hit) is often worse than the gamma.

No more aluminum foil hats for me

[m_chan]

I can finally look fashionable while thwarting the cia's mind readers instead of that baked potato look I had going for me.

radiation suits is a misnomer

[weglian]

I was a Navy nuke, so I know a thing or two about radiation. What people think of as "radiation suits" are not designed to shield radiation. They are used to prevent contamination. The suit prevents radioactive material from getting on your skin and clothes, so that you don't take it home with you. There are several kinds of radiation. Alpha particles are helium nuclei (He4). These particles are not dangerous unless you ingest or breathe them into your lungs. The dead layer of skin on your hand is enough to stop them. If they get into your body, they cause serious harm, as there is no "dead layer" of anything to stop them. Beta particles are electrons. They are light and fast, so they penetrate more. They will give you a dose to your skin, but not much deeper than that. A contamination suit can probably stop Betas. Even the old ones. Gammas are photons/electromagnetic radiation. Whatever you want to call them. X-Rays, microwaves, and radio waves all fall into this general category. The real biological hazard comes from the high energy particles/waves. These will pass right through your skin and can affect your internal organs. A contamination suit is not expected to reduce the dose from gammas. neutrons are produced in fission and some rare decay events, mostly shortly after a fission event. Neutrons are the only thing that can make something ELSE radioactive. Neutrons have no charge, so shielding them is difficult. It takes LOTS of lead or iron or water, etc. I don't care what their material is made of, if it's light enough to wear, it will not shield neutrons well. The web site said that it shileds low energy gammas, alphas, and betas. Low energy gammas don't cause much harm. Unless you work with a low energy gamma source on a routine basis, this material is not going to change your life. Or your life expectancy. This is my first post. Is it WAY too long? Sorry. -John