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Gamma-Ray Bending Opens New Door For Optics

Soulskill posted about 2 years ago | from the it's-hard-to-do-optics-work-through-doors dept.

Science 65

sciencehabit writes "Lenses are a part of everyday life—they help us focus on words on a page, the light from stars, and the tiniest details of microorganisms. But making a lens for highly energetic light known as gamma rays had been thought impossible. Now, physicists have created such a lens, and they believe it will open up a new field of gamma-ray optics for medical imaging, detecting illicit nuclear material, and getting rid of nuclear waste."

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Other uses (4, Funny)

azalin (67640) | about 2 years ago | (#39938687)

... and irradiated spiders that bite school children who become photographers

Wrong superhero (1)

sanman2 (928866) | about 2 years ago | (#39938705)

Don't make me bendy - you wouldn't like me when I'm bendy

Re:Wrong superhero (5, Funny)

azalin (67640) | about 2 years ago | (#39938789)

those were the good old days when we still though gamma rays gave you super powers instead of cancer

Re:Wrong superhero (3, Interesting)

clickclickdrone (964164) | about 2 years ago | (#39938967)

those were the good old days when we still though gamma rays gave you super powers instead of cancer

Humph. Next thing you'll be telling be cigarettes aren't a health giving natural way to relax

Re:Wrong superhero (1)

Darinbob (1142669) | about 2 years ago | (#39945289)

Marlboro Man. Once a mild mannered sanitation engineer, he turned super hero after accidentally smoking a pack of irradiated cigarettes. Able to empty entire restaurants with a single exhale he spends his days fighting the evil plots of General Surgeon.

Re:Wrong superhero (1)

RaceProUK (1137575) | about 2 years ago | (#39939505)

We just haven't found the right dose yet ;)

Re:Wrong superhero (-1)

Anonymous Coward | about 2 years ago | (#39940381)

> We just haven't found the right dose yet ;)

Is the phaser set on stun?

Re:Wrong superhero (4, Informative)

lobiusmoop (305328) | about 2 years ago | (#39940149)

Actually, gamma rays can be used to cure cancer rather than give you it - they are part of some radiotherapy regimes.
When I had a month of radiotherapy many years ago, it had a kind-of reverse Hulk effect though - rather than turning green, bulking up and gaining mega-strength, I went sunburn-red, dropped 30 pounds and needed to sleep up to 16 hours a day.

Re:Wrong superhero (2)

azalin (67640) | about 2 years ago | (#39941869)

The reason for this is that cancer cells are often more vulnerable to radiation and poisons (chemotherapy) because they multiply faster. Sad thing is that most of the things we use today to fight cancer, work by killing cancer cells faster than normal cells.
I hope it worked for you and Anti Hulk never needs to make another appearance.

Re:Wrong superhero (1)

sanman2 (928866) | about 2 years ago | (#39946235)

I thought it's because high-frequency radiation can be aimed more precisely, while also delivering lots of energy to burn targets quickly. (eg. "gamma-knife")

Re:Wrong superhero (1)

Chris Burke (6130) | about 2 years ago | (#39944401)

those were the good old days when we still though gamma rays gave you super powers instead of cancer

You mean... they aren't the same thing?

* Puts Tumor Man costume back in the closet.*

Re:Other uses (3)

Grayhand (2610049) | about 2 years ago | (#39938959)

Wow, Major geek demerits! Gamma rays would turn the school children green and give them muscles that any body builder would envy. For shame!

Re:Other uses (1)

triffid_98 (899609) | about 2 years ago | (#39939265)

Are you sure? Lou Ferrigno said it's all about steroids and green body paint.

Your ignorance makes me so angry!

Believe me you wouldn't like me when I'm angry...

Re:Other uses (1)

ByOhTek (1181381) | about 2 years ago | (#39939423)

Wow, Major geek demerits! That only is for direct application of the radiation. The GP is correct, as he had indirect application through a spider.

Re:Other uses (1)

Ukab the Great (87152) | about 2 years ago | (#39939659)

"Get a firm muscular body without needing to take dangerous nutritional supplements unapproved by the FDA. Or exercising. Yours for only 2000 low monthly installments of $19.99".

Fogbank? (0)

ka9dgx (72702) | about 2 years ago | (#39938723)

I bet this is what the mysterious "fogbank" material that the Feds forgot how to make actually does inside Thermonuclear devices.

Re:Fogbank? (4, Insightful)

Anonymous Coward | about 2 years ago | (#39938833)

when you think to yourself "I know, I'll mention something obscure that people will need to look up on Wikipedia to know wtf I'm talking about!", you might want to double-check that Wikipedia doesn't contradict your claim.

Re:Fogbank? (2)

Neil Boekend (1854906) | about 2 years ago | (#39938997)

Fact checking is outdated.

Re:Fogbank? (2)

ka9dgx (72702) | about 2 years ago | (#39939835)

I'm just trying to figure out how the puzzle pieces go together.

It wouldn't surprise me to learn that when "fogbank" is turned into a million degree plasma, that it has a refractive index high enough to focus gamma rays, or high energy x-rays. Or it could turn out that there it acts as a negative index metamaterial.

Gadgets are fascinating things, one can never truly be sure of how they work, unless one has a clearance, and a well defined need to know. (I have neither).

For example,I was surprised when reading about the development of the Hydrogen bomb that cardboard and styrofoam were both critical components in the focusing of energy on the secondaries. Environments that last for billionths of a second before self destructing, which cost millions to set up aren't in the domain of the typical experimenter. ;-)

Re:Fogbank? (1)

kaspar_silas (1891448) | about 2 years ago | (#39951903)

It would surprise me and most Atomic physicists. The exact made up of weapon components is secret but the interactions of X-rays with matter, even hot dense matter is not and such experiments are well within the domain of even an average university lab.

Not impressive yet (4, Insightful)

sFurbo (1361249) | about 2 years ago | (#39938729)

While this is an interesting deveopment, it is important to note the caveats: The refractive index in silicon, the only material tested so far, is only 1.000000001. IF this theory of how this is accomplished is correct, this MIGHT be higher for heavier elements. That's a big IF.

Re:Not impressive yet (1)

tinkerton (199273) | about 2 years ago | (#39938879)

Even if it's guaranteed to be higher, say a factor 10 (i mean 1.00000001) , then the big IF is if this is usable.

n = 1.000000001 (1)

Anonymous Coward | about 2 years ago | (#39938741)

I call: "This will never work the way you want it too."

Re:n = 1.000000001 (4, Insightful)

goodmanj (234846) | about 2 years ago | (#39938977)

Agree. Even if you do it with depleted uranium, and you suppose the "virtual electron effect" increases in proportional to the square of the number of protons in the nucleus, you might get an index of refraction in the ballpark of n = 1.000000033. Applying the lensmaker's formula [mtsu.edu], a convex lens with radii of curvature of 1 cm will have a focal length of ....

150 kilometers.

So the gamma ray imaging camera you want to build for airport security will have to be roughly the same size as your flight. No, not the length of the plane, the mileage.

Re:n = 1.000000001 (2)

azalin (67640) | about 2 years ago | (#39939279)

Where are the "artists conception"s when you need one. Maybe if you built it on top, you could have a dome over the entire continental US. That should be big enough to provide a reason to raise the TSA budget again. Because security!

Re:n = 1.000000001 (0)

Anonymous Coward | about 2 years ago | (#39939405)

I'm pretty sure the TSA will get the necessary funds and everything to deploy the system.

Re:n = 1.000000001 (0)

Anonymous Coward | about 2 years ago | (#39939893)

So the gamma ray imaging camera you want to build for airport security will have to be roughly the same size as your flight.

Overstating the case slightly? For some destinations I'd have to travel that far just to get to the airport, and I live in a country with a very high density of airports.

Re:n = 1.000000001 (1)

goodmanj (234846) | about 2 years ago | (#39941061)

Not really. The focal length is the *minimum* distance at which light can be focused, if the object you're imaging is infinitely far away. If you add up the overall length, from object to lens to detector, the minimum length is 4 * f = 600 km.

But hyperbole or no, I was going for an order-of-magnitude estimate. Anything over 100 m would prove the point.

Re:n = 1.000000001 (3, Informative)

kebes (861706) | about 2 years ago | (#39940985)

I'm somewhat more hopeful than you, based on advances in x-ray optics.

For typical x-ray photons (e.g. 10 keV), the refractive index is 0.99999 (delta [lbl.gov] = 1E-5). Even though this is very close to 1, we've figured out how to make practical lenses. For instance Compound Refractive Lenses [wikipedia.org] use a sequence of refracting interfaces to accumulate the small refractive effect. Capillary optics can be used to confine x-ray beams. A Fresnel lens [wikipedia.org] design can be used to decrease the thickness of the lens, giving you more refractive power per unit length of the total optic. In fact, you can use a Fresnel zone plate [wikipedia.org] design, which focuses the beam due to diffraction (another variant is a Laue lens which focuses due to Bragg diffraction [wikipedia.org], e.g. multilayer Laue lenses are now being used for ultrahigh focusing of x-rays). Clever people have even designed lenses that simultaneously exploit refractive and diffractive focusing (kinoform lenses [cornell.edu]).

All this to say that with some ingenuity, the rather small refractive index differences available for x-rays have been turned into decent amounts of focusing in x-ray optics. We have x-rays optics now with focal lengths on the order of meters. It's not trivial to do, but it can be done. It sounds like this present work is suggesting that for gamma-rays the refractive index differences will be on the order of 1E-7, which is only two orders-of-magnitude worse than for x-rays. So, with some additional effort and ingenuity, I could see the development of workable gamma-ray optics. I'm not saying it will be easy (we're still talking about tens or hundreds of meters for the overall camera)... but for certain demanding applications it might be worth doing.

Re:n = 1.000000001 (1)

goodmanj (234846) | about 2 years ago | (#39942977)

You're right, that something can be done with this. But the original poster's point was that "This will never work the way you want it to." Not that it can never work, but it's a hell of a lot more complicated than anyone would hope. My post was intended to show just how badly "the way you want it to work" fails.

Re:n = 1.000000001 (2)

Chris Burke (6130) | about 2 years ago | (#39944523)

I would assume that "work the way you want it to" means the effect as in "lets us do the things we want to do", not the mechanism for achieving it as long as that mechanism is reasonable -- this is why the naive single-lens method doesn't work, because it's completely unreasonable to build such a giant lens, right? But who cares if there's a nice relatively compact way to make it work?

If "the way you want it to" work is with a single lens, most visual optic devices outside of spectacles don't "work", either.

Re:n = 1.000000001 (1)

MozeeToby (1163751) | about 2 years ago | (#39941277)

150 km, so what? They're largely non interacting with the atmosphere, you could set up your lenses in one place and your detector in another. No more difficult than any number of neutrino experiments. Or use a constellation of satellites, you could put the detector thousands of miles away if need be. Might be a 'big science' kind of project, but that doesn't mean it's not a usable phenomenon.

Re:n = 1.000000001 (0)

Anonymous Coward | about 2 years ago | (#39942887)

While gamma rays are quite good at penetrating light shielding, they are still attenuated by air. A rough back of envelope calculation gives an attenuation of factor of 40 for each kilometer of air for gamma rays in the 0.1 - 2 MeV range. By ~60 km, that is an attenuation of a factor of 10^100.

Re:n = 1.000000001 (3, Insightful)

rgbatduke (1231380) | about 2 years ago | (#39942621)

Well, yeah, except that all of the bending occurs at the interface surface. So in principle, one could stack 150 lensing surfaces constructed Fresnel-style and bring that right down to a kilometer. Depending on what the "interface surface" is for gamma rays. Or, stack 1500 of them and bring it down to 100 meters. Or stack 15,000 of them, in a 3D structure created with e.g. molecular beam epitaxy, and bring it down to 10 meters (with a lens with a total length of perhaps a meter). At that point it is conceivable that it might be useful, although probably not as an optical grade lens (wouldn't it be uber cool to build a gamma ray telescope with an aperture lens a meter across? Sure it would!)

I think that a lot of these same principles are involved in building x-ray lenses -- the lens is less like a glass lens, more like building an interferometric scattering array that causes a single central primary peak. But not my specialty, just thinking out loud...


Re:n = 1.000000001 (0)

Anonymous Coward | about 2 years ago | (#39942711)

I've already seen talks of space based x-ray telescopes with focal lengths measured in kilometers. It might not be of much use for airport security. But there is a lot of room in space and already people working on the issue of flying two satellites in tandem to deal with long focal length based telescopes.

Re:n = 1.000000001 (0)

Anonymous Coward | about 2 years ago | (#39942971)

Indeed, but that's not a problem. We need the gamma-ray lensing to start fucking with those leather-godesses of phobus... Have to call their attention somehow, and *NOTHING* works better as a beacon in this universe as a gamma-ray source (this part is not a joke).

Re:n = 1.000000001 (1)

budgenator (254554) | about 2 years ago | (#39943119)

Agree. Even if you do it with depleted uranium, and you suppose the "virtual electron effect" increases in proportional to the square of the number of protons in the nucleus, you might get an index of refraction in the ballpark of n = 1.000000033. Applying the lensmaker's formula [mtsu.edu], a convex lens with radii of curvature of 1 cm will have a focal length of ....

150 kilometers.

Well first they can get much smaller radii of curvature using the good old fashioned fresnel lens [wikipedia.org] technology; with photolithographic [wikipedia.org] fabrication the could not only get the lens radii of curvature down into the micrometer range they could stack hundreds or thousands into a lens system only a cm thick and only expend trivial effort.

Lensmen? (0)

Anonymous Coward | about 2 years ago | (#39938777)

those guys could do some mind bending things

Would be interesting (1)

Big Hairy Ian (1155547) | about 2 years ago | (#39938829)

to see this applied to Gamma Ray Bursts bearing in mind they burn more energy in an hour than our Sun will in it's 4 billion year life! Of course there's also applications for Gamma Ray Specs!!! Kewl

Re:Would be interesting (1)

Martin Blank (154261) | about 2 years ago | (#39939801)

Gamma ray bursts are not objects themselves, but the result of the death of a supermassive star (or more rarely the merging of two neutron stars) and last no more than a few minutes, though most last under one minute. The energy output is considerable, but it's larger than you listed, putting out more energy than the sun ever will over the course of 10 billion years (from initial formation through red giant). We really don't want a nearby one pointed at us.

On the totally unrelated topic of your signature, I prefer the following version: "Set a man a fire, and he'll be warm for the night. Set a man afire, and he'll be warm for the rest of his life."

Gammasphere Pokes! (1)

Anonymous Coward | about 2 years ago | (#39938947)

Admittedly, Gammasphere is quite primitive. It uses time and energy differentially ordered spectra to deduce rotation and energy levels of very short lived multi- level Yrast Gamma levels. Through computer analysis; the data is otherwise really quite disordered. And there is no focussing, Gammasphere is what is known as a 4pi detector. Omnidirectional.

    Focussed X-Ray spectroscopy is routinely performed now, at Light Sources, through advances in Material science; how to best deduce spectra is by the use of... wait for it... mirrors? Mirrors. It is all done with mirrors. Just not the kind found in Walmart.

    Mirrors needed to image Gamma rays would need to be kept very, very cold indeed. And ordered. As in let's keep the top Quarks, or any other Quarks, all pointing up.

    Hulk Smash!

Emm no (2)

kaspar_silas (1891448) | about 2 years ago | (#39939019)

It's too small to be useful in tradition lens applications. Even at lower X-ray/Gamma energies when the refractive index is much bigger ( see: http://henke.lbl.gov/optical_constants/getdb2.html [lbl.gov]) you can't really use make reasonable lens.

It would be far far easier to increase the "commonly" available divergent sources' intensity than attempt to recover losses due to divergence with such a weakly focusing system. Hell, you could likely achieve a much bigger intensity increase by moving the source closer.

Can anyone even think of the medical imaging system they are envisaging. I assume they mean a phase-contrast approach but that needs a intense 700kV source with a small spot size and thin structured grating that absorb 700kV photons (which I don't think exist thou it's maybe just about within the capacity of man to make them).

The only application I can think of for this is for X-ray telescopes and astrophysics where you can't increase the source but you can have massively long imaging systems. However I will bet that their are not many interesting astrophysical events that emit only 700kV+ photons and the attenuation of the massive silicon lens may well counteract the benefit of the focusing.

Other potential gamma ray lens (2, Informative)

Anonymous Coward | about 2 years ago | (#39939151)

It seems the idea of focusing gamma rays isn't as new. ESA made a study on it years ago. They proposed multilayer coatings and Laue crystals.
ESA study on gamma lens [esa.int]

shhhh... (4, Insightful)

harvey the nerd (582806) | about 2 years ago | (#39939355)

don't tell TSA or they'll gamma nuke everybody until they glow.

Re:shhhh... (1)

Anonymous Coward | about 2 years ago | (#39939775)

Too bad I don't have mod points. The security scanner industry execs must be lining up around the corner to shove these things in every bus depot, airport, and mall in the world. who cares about a little bit of cancer.

Another use (0)

Anonymous Coward | about 2 years ago | (#39941103)

turns your skin green when you get angry.

Not just for looking... (1)

a-zA-Z0-9$_.+!*'(),x (1468865) | about 2 years ago | (#39943877)

Currently, integrated circuits like CPUs are fabricated using UV light, wavelength 10^-8m. Gamma rays are 10^-12m long. All other things being equal (but they never are...), this may lead to chips with 10^4*10^4=10^8 more features. This might be worth constructing a 100m long gamma ray lens or two.

Re:Not just for looking... (0)

Anonymous Coward | about 2 years ago | (#39951099)

EE student here (graduating tomorrow).

The problem with your thinking is that we've already started to run into problems with the gate length of transistors becoming to short at 23 nm. We're developing solutions to this, the most interesting (to me, at the moment) in FinFET technology, which I'm led to understand is used in Intel's Ivy Bridge chipset.

That's not to say that getting smaller feature size wouldn't result in improvements, (ignoring that we're also getting pretty close to lattice parameter) but you can also see from the above comments that this development won't be very practical without huge improvements. This is just the very first (very cool) step.
And I know you said feature size, but I don't want anyone to be misled that this translates directly to smaller transistors. There are a lot of improvements that need to made in our tech for this to be useful. And even then we currently have e-beam lithography, with a wavelength on the order of picometers, so given that that has a feature size on the order of nm, I'd guess it'll be a while before gamma-ray exposure can make sub-nm features.

Not to mention that a gamma source as bright as the current UV sources would difficult to make safe. (but it might not need to be as bright since gamma rays are so much more energetic)

How can this help in getting rid of Nuclear waste? (1)

Anonymous Coward | about 2 years ago | (#39944637)

When I was reading the article, I noticed that they said that these gamma ray optics might help in getting rid of Nuclear waste. That really piqued my interest. I assume that this newly discovered material for gamma ray optics will help scientists focus gamma rays, and make the gamma ray source focused/focused enough to help accelerate the “evaporating” of protons or neutrons from nuclear waste?

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