Lightweight Radiation-proof Fabric? 92
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."
Imaginary Particles? (Score:2)
And hence the illusion of being protected...
Re:Imaginary Particles? (Score:5, Informative)
Re:Imaginary Particles? (Score:2)
Evidently, to no real effect.
Re:Imaginary Particles? (Score:1)
Re:Imaginary Particles? (Score:1)
Re:Imaginary Particles? (Score:2)
It must be deja vu fabric ... (Score:1)
Re:It must be deja vu fabric ... (Score:1)
Volume (Score:5, Funny)
No, weight (Score:3, Informative)
Re:No, weight (Score:4, Insightful)
Weight might not be a big issue once you are actually in space, however, it is a huge issue when it comes to getting there.
And once you're in orbit weight doesn't matter, but mass still does.
Re:Volume (Score:1)
Re:Volume (Score:3, Insightful)
Re:Volume (Score:1, Redundant)
Ummm... heavier stuff requires more energy to get it off Earth into space, so yes, weight is an issue.
Underwear (Score:1)
Re:Underwear (Score:2)
Re:Underwear (Score:1)
No worries then (Score:3, Interesting)
Testing (Score:5, Informative)
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 (Score:1, Informative)
Re:Testing (Score:5, Informative)
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.
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.
Re:Testing (Score:1)
Re:Testing (Score:2, Informative)
Question, (Score:5, Funny)
I'm only asking because I'm trying to figure out whether Superman can see through it. Any help is appreciated.
-Lex.
Re:Question, (Score:2)
Well obviously his glasses use leaded glass.
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Re:Question, (Score:3, Funny)
*** NEWS FLASH ***
Breast cancer rates alarmingly high in the city of Metropolis. Former reporter Lois Lane tells us how the strange burning sensation turned into a nightmare
Jimmy Olsen, Daily Planet News
*******************
Metal detectors (Score:3, Interesting)
Can I stuff a duffle bag full of guns and make them not show up on that little thing?
For the cost it probably wouldn't be worth it though.
Re:Metal detectors (Score:2)
Re:Metal detectors (Score:2)
Re:Metal detectors (Score:2)
metal detectors work by generating an electromagnetic field, and sensing any disruptions caused by the movement of metal objects through the field.
Re:Metal detectors (Score:2)
Does it protect against Scammer Rays? (Score:5, Insightful)
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.
Not sure how comparable to lead it will be. (Score:2)
Re:Not sure how comparable to lead it will be. (Score:1)
Re:Not sure how comparable to lead it will be. (Score:1)
Post-humans, if they are ever allowed to exist, will be free to take their silicon bodies wherever they want to go, without limits.
Bottom line: The stars are not for man.
Re:Not sure how comparable to lead it will be. (Score:2)
Re:Not sure how comparable to lead it will be. (Score:2)
> help with the radiation issues they are currently
> having aboard the ISS.
I doubt it. Those problems are due to high-energy particles striking the alumimum hull and producing cascades of high-energy photons. The best solution would be to replace the aluminum with plastic.
I don't understand why they didn't see this coming.
No more aluminum foil hats for me (Score:5, Funny)
Re:No more aluminum foil hats for me (Score:2)
other applications (Score:3, Interesting)
DAMMIT! (Score:1, Interesting)
Re:DAMMIT! (Score:2)
Moderation totals: -1 (Disgusting)
Cell phones (Score:2)
If you are really that woried, just wear your tin foil helmet. It will "protect" you.
Underwear (Score:2)
Re:Underwear (Score:3, Insightful)
Re:Underwear (Score:3, Informative)
- Throw away your alarm clocks and wrist watch, the glowing hands give you 0.6 mrem/year.
- Or try giving up bananas, most people recieve about 40 mrems/year per year in Potassium-40 radiation
- But the absolute worst source of radiation, cigarettes- 1.5 packs per day = 8000 mrem/year
- And move away from coal fired plants; Uranium occurs naturally in coal, which when burned exposes you to 1-4 mrems/year
All thanks to having a girlfriend at a national lab (which probably means she radiates more than your wifequestion (Score:1)
From what I remember of polymers, they are essentially composed of long string-like molecular structures. With such a structure, it is easy to orient the molecules into specific directions. Add a little vulcanizing effect for strength; voila! Strength, high density of electrons, flexibility (similar to tire rubber), and wearable?
Re:question (Score:2)
> (similar to tire rubber), and wearable?
Just like a plastic bag. And just as effective.
Would a pair of these pants... (Score:1)
...confuse the filters so that one could pour hot grits down them and still post such nonsense?
Wow. (Score:1)
radiation suits is a misnomer (Score:5, Informative)
Re:radiation suits is a misnomer (Score:1)
These particles are not dangerous unless you ingest or breathe them into your lungs.
As you said, it's not as much about protecting against the radiation as it is protecting against contamination. Along that line, you wouldn't want to ingest a material that was emitting alpha particles, you don't have to worry about ingesting the particles themselves.
Re:radiation suits is a misnomer (Score:1)
Re:radiation suits is a misnomer (Score:2)
Not to long, just use a bit of whitespace between paragraphs. Use <p> or <br> if you are posting using html format.
Also, mentioning first posts is being frowned upon here :)
Re:radiation suits is a misnomer (Score:2)
Faraday cages are effective if the radiation wavelength is bigger than the cage net. As you increase radiation energy the wavelenght gets smaller. You can still reflect it by decreasing the aparent net size as seen from the photon.
That's why a X-ray telescope uses special mirrors that reflect radiation at shallow angles (1 or 2 degrees). Those pthtons see the atom lattice from shallow angle, therefore it looks smaller.
Perhaps this kind of polymer has an high eletronic density as seen from most angles, therefore being effective against most low energy X-rays for example.
I doubt it has any effect against hard X-rays, or gamma rays, witch are generally deflected by direct interaction with the nucleus charge, and not with the eletron clouds, but it could be effective against low energy X-rays (1-2 Kev or so).
Flight crew (Score:3, Funny)
Secondary emissions? (Score:4, Informative)
Secondary emissions are a very real bane of shielding for interplanetary travel, due to the extremely high energies of cosmic rays. Even if you could launch lead shielding for a spacecraft, manageable thicknesses would cause secondary emissions that were even more dangerous to the occupants than the original cosmic rays.
They've tried a new type of radiation shielding on the ISS made of polyethylene that is supposed to block without creating secondaries, and I see that's part of this fabric. Unfortunately the new shields don't seem to be as effective as hoped.
Radiation is anticipated to be a big problem on a Mars mission. IIRC, the radiation exposure will have a cancer risk equivalent to a lifetime of smoking.
But you really know to be scared of cosmic rays if they make rapping noises on your spacecraft, and upon return to Earth you start stretching, bursting into flame, become invisible, or turn into a pile of muscular orange bricks.
Re:Secondary emissions? (Score:2)
> secondary emission characteristics of this
> fabric.
Because it has essentially none. Heavy high-energy particles such as cosmic rays will zip right through it as if it wasn't there.
> They've tried a new type of radiation shielding
> on the ISS made of polyethylene that is supposed
> to block without creating secondaries,...
It isn't new and it isn't supposed to block without creating secondaries: it is supposed to block secondaries. Better to get rid of the metal that is creating them in the first place.
>
Yup. They'll sell lots of their expensive plastic bags.
Re:Secondary emissions? (Score:2)
Yes, but most astronauts would gladly take up smoking for an entire lifetime if it meant they could go to Mars
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Re:Secondary emissions? (Score:1)
A more immediate and practical use (Score:2)
--psy
Z for Zacharia (Score:1)
Major league baseball.. (Score:1)
Perhaps even get a date in my trendy new radation proof pub cap.
Perhaps not.
Re:Major league baseball.. (Score:1)
Upgrade man, upgrade. I wear these [lessemf.com]. The ladies are all over me in my baseball cap, underwear, t-shirt, and scarf.
I'm joking of course. I'd have to leave the house.
magnetic field (Score:3, Funny)
Some Additional Information (Score:3, Informative)
This is bullshit and I can PROVE it. (Score:4, Informative)
Check out their "test results." [radshield.com] (PDF file) Go to page 3 to see the blocking power of their fabric.
Error #1: There is no such unit as a Kv. They mean KeV, as in Po-210 emits an alpha particle with 5,300 KeV of energy. But this is minor.
Error #2: X-rays and gamma rays are both photons; they're only distinguished by their energies. But the X-ray results and gamma ray results (which overlap in energy, which, in itself, makes no sense) contradict each other. For example, why does the fabric block only 52% of 60KeV gamma rays, but 82% and 72% of 50 and 70KeV X-rays respectively? Makes no sense, but this is nothing compared to...
Error #3: The real killer, and what makes me suspect this is fraud, rather than mere incompetence. They use 0.5 mm of lead as the comparison for their gamma emitter tests. The radiation-absorbing properties of lead are well known, and easily accessible in handy-dandy tables. For example, the half-value layer (the amount of material needed to block 50% of incoming radiation) for a Co-57 source is 0.15 mm of lead (ref here [stanford.edu] ), so 0.5 mm of lead should block more than 90% of the radiation, not just 52%. Proof positive that they're full of shit.
Fuck them, and fuck New Scientist. (Pardon my French.)
Minor clarification (Score:2)
and, er... (Score:2)
Re:and, er... (Score:2)
Most gamma ray sources tend to be mono-energetic, so if you have a source of 60 keV (kiloelectronVolts) gamma rays, that's all you have. On the other hand, if you have a 60 kV (kiloVolts) x-ray source (the tube operating potential) you have x-rays anywhere from 10-60 keV, with most of them probably around 25-40 keV. The effective energy of this beam will be around 30 keV.
Note the distinction in units. Subtle but very different.
Getting back to the difference in absorption, since the x-ray beam has a much higher proportion of low energy photons compared to the gamma ray source, more of these will be absorbed by the material. Thus more of the x-ray beam would be absorbed, compared to the gamma ray source.
Their results aren't bogus...they're just comparing apples and oranges (which may be just as bad).
Re:and, er... (Score:2)
0.5 mm lead should be more than sufficient to stop all of a 50 kV x-ray beam and most of a 70 kV beam.
I certainly wouldn't expect 0.5 mm lead to stop all of a 60 keV gamma ray source though. Most of it definitely.
However, the document doesn't go into any of the details of how the material was tested. But still, it does raise some questions.
then again, the x-ray part of the table mentions broad beam apparatus, which means scatter radiation was included. including scatter radiation makes it look like more radiation reached the detector, decreasing the apparent blocking ability.
this would probably account for why their 50 kV beam was only partially attenuated instead of fully, and why the other x-ray energies aren't blocked as much as they should have been.
Re:and, er... (Score:2)
Re:and, er... (Score:2)
However, this doesn't address my main objection, and I contend that the results are bogus. Are my calculations wrong about 0.5 mm of lead blocking more than just 52% of the Co-57 emissions?
And re: gamma rays vs. x-rays: obviously different fields of physics have slightly different definitions. The one I'm familiar with is just based upon energy; there's a not-too-well defined border between x-rays and gamma rays at about 0.1 MeV. Your definition, on the other hand, works in almost all cases, but I can give a few counterexamples; e.g. x-rays from astrophysical sources can be thermal/black body rather than electronic in origin, and gamma rays need not come from a nuclear process, but from, say, the annihilation of an electron with an anti-electron. But since yours is a reasonable definition, I withdraw my parenthetical objection in the original posting.
Re:The difference between X-rays and Gamma rays (Score:2)
Even if you are right, there is still no difference in the photons themselves. We are talking about electromagnetic radiation, for which the only real defining characteristic is the energy (frequency, wavelength, and energy are all determined by each other). If the energies of the reported gamma rays and the energies of the so called X-rays overlap and the absorbency is way different, I would have to agree that these people are indeed full of shit, and that New Scientists does indeed deed to be f*cked.
Re:This is bullshit and I can PROVE it. (Score:2)
The distinction between x and gamma rays is their origin.
gamma rays are nuclear in origin, resulting from the decay of radionuclides.
X-rays are electronic origin, generated when an electron loses energy in some fashion (i.e. moving from a higher energy level to a lower energy level).
aside from that, there is no way to tell a gamma photon from an x-ray photon.
Re:This is bullshit and I can PROVE it. (Score:1)
Re:This is bullshit and I can PROVE it. (Score:2)
As for 90% vs 84%, my calculation was nothing more complicated than 1 - (0.5)^(0.5/0.15), so I obviously defer to the numbers of an expert. :)
And as for other outrage on the internet, Bob Park's What's New column at www.aps.org mentioned it, which is always the kiss of death. But it's been pretty quiet other than one thread in a physics-related newsgroup, as far as I can tell.
Durability of these things. (Score:2)
Maybe they can sell a bunch to India and Pakistan,
Re:Durability of these things. (Score:1)