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GeV Acceleration In 3 Centimeters 151

ZonkerWilliam writes, "Here is a very interesting article, for the scientific community at least, on an advancement in laser wakefield particle accelerators. Being able to accelerate electrons to 1 Gev in the space of 3.3 cm calls up visions of portable devices that can be used anywhere: think of portable cancer therapies, if they can do the same for positrons, portable PET scans, possible use in compact fusion devices, capturing the dearly departed, etc. The uses are mind boggling." From the article: "By comparison, SLAC, the Stanford Linear Accelerator Center, boosts electrons to 50 GeV over a distance of two miles... The Berkeley Lab group and their Oxford collaborators... achieve a 50th of SLAC's beam energy in just one-100,000th of SLAC's length." I doubt that this tech will fit on a table top anytime soon. The article quotes the Berkeley researcher: "We believe we can [get to 10 GB] with an accelerator less than a meter long — although we'll probably need 30 meters' worth of laser path."
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GeV Acceleration In 3 Centimeters

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  • Blasters (Score:2, Funny)

    by tygt ( 792974 )
    How many eV would it take to make Han Solo's blaster? :)
    • Re: (Score:2, Funny)

      by Anonymous Coward
      Eh, get back to me when we have the batteries capable of making an energy weapon that'll do more than warm food. Of course, we could just use some of those recalled Sony batteries as grenades instead :-)
      • Re: (Score:2, Funny)

        An extension cord! An extension cord! My kingdom for an extension cord!
      • Say what?? you're made of food. Any energy weapon that "warms food" is perfectly capable of being lethal to your person.
        • by RsG ( 809189 )
          It takes a lot more energy to kill someone than it does to warm them. Ever used a microwave? That certainly warms food quickly. Microwave radiation on that level could hurt like hell if you were exposed to it, but it would tak an awful lot more power than a kitchen appliance to fry you. We could certainly build an EM or particle weapon that could fry a human, but it wouldn't be easy. And power storage is a big issue.

          Batteries don't actually have a lot of juice. Think about laptop batteries as an examp
    • by ChePibe ( 882378 ) on Wednesday October 04, 2006 @12:10AM (#16301125)
      I believe Han Solo's only notable piece of equipment is a small bouquet of daisies, one of which he gives to Guido in the super-hyper-ultra-master-remix of Star Wars Episode -12.

      Why on earth would Han want to "blast" anything, as is? He's a perfectly legitimate businessman, brought into hard times by a pair of misfits who attack people with Mag Lites... or at least that's the latest Lucas version.
    • by eonlabs ( 921625 )
      Tell me no one caught the ghostbusters proton gun comment...
  • PET Scan (Score:1, Funny)

    by yamamushi ( 903955 )
    If I want a PET scan , I'll go to the vet.
    • Re: (Score:2, Funny)

      by kfg ( 145172 ) *
      I don't bother scanning for 'em, at this point if I so much as suspect I have a PET I just call in the exterminator. I've really gotta start bein' more careful about shutting my back door.

      The racoons and possums I was able to deal with myself in fairly short order, but it took 18 years to get rid of that damned cat.

      KFG
    • If I want a PET scan , I'll go to the vet.

      I don't know what kind of modifications you've done to your PET, but my PET can't do more than 40x25 character mode. So I don't really see the point in hooking a scanner up to it. Even if you find a vet from the great computer wars, I seriously doubt he'd be able to help. He'd probably just tell you to get a Commodore 64 instead. At least it had bitmapped graphics.

      You kids and your screwy ideas.
    • Why would anyone scan PolyEthylene Terephthalate?
  • 1.21 GigaWatts (Score:1, Offtopic)

    by c0d3r ( 156687 )
    In what distance can they generate 1.21 GigaWatts? 88 Miles for 1 hour? Capacity for Flux Generators?
    • Dunno, but if they're only just believing they'll get 10GB in to a metre then maybe they need to go look at an iPod?

      Oh, hang on, this is slashdot. I'll ignore the non-proof-read posts, shall I? At least TFA doesn't have this error...
      • Haven't you ever looked inside an iPod? There's at least six meters of internet tubes in there!
  • by Renraku ( 518261 )
    Well, with this we might have to worry about raidation-shielding on armored vehicles. What's the point in armor at all if they can shine enough of these at your armored SUV?
  • At last! (Score:4, Funny)

    by SysKoll ( 48967 ) on Wednesday October 04, 2006 @12:14AM (#16301147)
    At last, a portable zap gun! About freakin" time!
  • One of the major issues with the deployment of such portable technology is the power requirements. If they could get it to run off solar power, that would be a major boon to the less wartorn parts of Africa.
    • Re: (Score:2, Funny)

      by kbox ( 980541 )
      Yeah, I have lost count of how many times i have heard those starving Africans saying "Man, I wish i could accelerate electrons to 1 Gev over 3cm".
      • Because no-one in Africa gets cancer? You don't even need to RTFA - it's in the summary.
        • Re: (Score:3, Insightful)

          by LWATCDR ( 28044 )
          They do but it would be a lot cheaper to move the patient to a hospital near a power grid than try to put one of these at every clinic.
          Cancer patients getting radiation treatment need a lot of care. I am not sure that they would have much of a chance of surviving at a local solar powered clinic with an MD and maybe a nurse running the show.
          Local clinics need to provide general care. Ideally any seriously ill patent would be transported to a larger care hospital for specialized care.
          The money that it would t
    • by gmby ( 205626 )
      What do they need this for in waterless desert?
      Maybe they need it to Microwave thier food in 2 seconds instead of 2 minutes?
      Oh that's right; NO FOOD THERE!

      Mods; WTF!?
    • that would be a major boon to the less wartorn parts of Africa.

      And we can use this technology to blow up the more wartorn parts of Africa.
    • Where's the -1:Inane moderation option when you need it?. Seriously, why would you need this in Africa? Why would being in Africa necessitate low power? Why would you think that a high peak power pulsed laser necessarily has a high constant power draw? Just for reference here, I use a 1.5 MW laser in my lab; it runs on 120 VAC, at ~3 amps.
  • by Khyber ( 864651 ) <techkitsune@gmail.com> on Wednesday October 04, 2006 @12:14AM (#16301151) Homepage Journal
    But if you only need 30 meters of laser path, wouldn't it be possible to just use different mirrors to reflect within the chamber to obtain the length needed, and can't you do it thanks to the light wavelength in nano (or pico??) meters?

    I'm not that educated in lasers, it wasn't as big of a study as mass-power mini railguns (no joking) to me. Someone PLEASE inform me and nobody bother modding me, I just want answers for my education.
    • by Ruie ( 30480 )

      But if you only need 30 meters of laser path, wouldn't it be possible to just use different mirrors to reflect within the chamber to obtain the length needed, and can't you do it thanks to the light wavelength in nano (or pico??) meters?

      I'm not that educated in lasers, it wasn't as big of a study as mass-power mini railguns (no joking) to me. Someone PLEASE inform me and nobody bother modding me, I just want answers for my education.

      It might be that's what they mean by "laser path" above, i.e. even th

      • by Khyber ( 864651 )
        But from what others say, even with a mirror, you're still going to lose that extra coherency because of photon collision, from what I understad about simple angles and how light usually reflects. Now that I've had my eyes opened to that, it's a bit clear you may need more than 30 meters. I notice they dont' exactly say the specifications of any mirros, if used, and they're not certainly giving the pure exact gas measurement if they're doing this. No blaming them, though, they made this process, and it's mo
        • by Ruie ( 30480 )

          But from what others say, even with a mirror, you're still going to lose that extra coherency because of photon collision, from what I understad about simple angles and how light usually reflects. Now that I've had my eyes opened to that, it's a bit clear you may need more than 30 meters. I notice they dont' exactly say the specifications of any mirros, if used, and they're not certainly giving the pure exact gas measurement if they're doing this. No blaming them, though, they made this process, and it's mo

    • Re: (Score:1, Informative)

      by Maxmin ( 921568 )
      RTFM: they're accelerating electrons, not photons, so mirrors won't work here.
      • by Khyber ( 864651 )
        RTFM? Sorry man, it's hard to RTFM when about half of the information I looked up from the bare info your info-lacking comment gave me isn't very readily available to simple-minded folk like me with excellent searching skills. Perhaps you've got the intelligence to give me a layman's-terms version of what I'm not seeing, without violating an NDA, without getting into how photons are different from electrons without them all being the near-same on a quark level?
    • Re: (Score:3, Informative)

      by forand ( 530402 )
      You need the laser to be coherent across the entire path so that the particles are able to "surf" the wave fronts. Simply adding mirrors does not accomplish this and even if you had a coherents length of 30 m; you can't get the acceration to occur in higher energy density any faster. Basically you need to experience the full slope of the wave front to get maximal acceleration.
      • Re: (Score:3, Informative)

        by Brietech ( 668850 )
        I actually do some research in this area (Plasma-wakefield particle acceleration, really really similar), and one of the biggest problems is getting the pulse-width incredibly small. They have to use something called Chirp Pulse Amplification and I think the beam length is somewhere on the order of 1-2 picoseconds. From the article, the power delivered by this beam is about 40 TeraWatts, which gives you some sort of idea. The acceleration gradient might be really high, but that doesnt mean youre going to ge
      • by Khyber ( 864651 )
        You might want to check http://www.wickedlasers.com/ [wickedlasers.com]

        They seem to have some ungodly powerful pen form-factor lasers as it is, good enough for cauterizing wounds or being visible in pure daylight with near any basic primary color during daylight. And these are for mainly military use, so I'd probably err on the side of caution on these guys as to the real power of even a LED-based laser, I fail to see how you're going to maintain a gas-based laser in that small of a form factor with the limited amount of powe
        • the laser over there do have a lot of oomph, but they are still 300mW or 0.3 watts, the lasers in the article are 9TW or
          0.3 vs. 9,000,000,000,000 watts. 9 TW doesn't melt plastic, it shreds atoms.
    • by deglr6328 ( 150198 ) on Wednesday October 04, 2006 @01:54AM (#16301661)
      No, the laser light is turned INTO the energy of the electron beam. It is not infinitely reusable.

      That said, I don't see very many posts yet which address the central importance of this news. So let me do that now. THIS IS HUGE HUGE HUGE NEWS. I would be shocked if the LOASIS group weren't on stage with the king of Sweden in a decade or so. Seriously, that's how big this is. No one expected things to happen this fast in wakefield acceleration. No one. Just two years ago I posted a story [slashdot.org] here about the latest achievement of the same wakefield acceleration research group. They were then at 80 MeV electron energies over millimeters of acceleration distance using a 10 terawatt laser pulse. With 1,000-2,000 trillion watt (petawatt) lasers coming on line in the next few years [rochester.edu] and this new multi-cm acceleration distance possibility it is not beyond the realm of the plausible to expect to see hundred GeV, possibly even TeV energies coming out of these things. It takes the Stanford linear electron accelerator 2 miles to accelerate its 50 GeV electron positron beams! What we are witnessing is nothing short of a revolution in particle acclerators that will open up new frontiers of high TeV scale particle physics faster than anyone ever thought possible. This is the sort of breakthrough that happens once in 3 or 4 decades.... if you're lucky.
    • Mirrors (1) lose some power with each reflection, and (2) introduce distortion into the beam because the mirror surface is not perfectly flat. Keeping the shape of the beam just right, according to the article, is crucial for getting this to work.
    • As the other posters said, the purpose of the laser is to accelerate electrons. The way it works is that Hydrogen is ionized, breaking apart into protons and electrons, and heated to form a plasma. A laser is shot through this plasma, and the electrons are "pushed" down the chamber. Assuming I understanding this correctly, if the photons were reflected back through the chamber, the electrons would be pushed the opposite direction, undoing the work of the first traversal.

      Now it's my turn to ask a question to
      • by trip11 ( 160832 ) *
        IAAPP. If (and at the moment this is the big question) they can achieve injection, in other words take electrons, accelerate them, insert them to another device and accelerate them again etc etc, then they may be able to create a 'wavefield ring. However there are other limitations to this. Curving the beam of electrons will cause them to accelerate in towards the center of the circle. A charged particle that is accelerating radiates photons (gamma rays) whichs causes it to loose energy. At some point
  • by BKX ( 5066 ) on Wednesday October 04, 2006 @12:15AM (#16301159) Journal
    capturing the dearly departed, etc.

    Holy Jesus, we can capture ghosts now with our 1 inch laser PET scans!!!
  • capturing the dearly departed

    So, are you saying that we can now capture ghosts with a particle thrower (Proton Pack). Damn, SciFi really DOES pave the way toward the future...

    Excuse me now while I hide from the Stay-Puft Marshmallow Man!
    • by vistic ( 556838 ) *
      This [wikipedia.org] doesn't look like a fun place to put them if they were that dear to you.

      I'm glad Wikipedia has an article on "Ghostbusters equipment".

      Now it just needs to be edited with this new information about GeV acceleration! We finally know how it works!
  • one needs a beam of sufficient luminosity / small emmitance  to be useful on its own wthough I suppose this could start off as an injector to a more traditional accelerator. 
  • Imagine (Score:2, Interesting)

    by mnmn ( 145599 )
    Imagine a Beowulf cluster of these!

    No seriously. If you can get 1GeV in 3cm and 10GeV in a few meters, the LHC is redundant before it got completed.

    It would kick ass if a group of undergrads somewhere complete an accelerator with the energy of the LHC and start testing the weak theory days before the LHC becomes operational. What was the cost of it again?
    • Re:Imagine (Score:4, Informative)

      by Vilim ( 615798 ) <ryan@jabber w o ck.ca> on Wednesday October 04, 2006 @12:33AM (#16301273) Homepage
      Seeing as how the LHC produces two beams in opposite directions with energy 7 Tev each (total collision energy is 14 Tev) this accelerator has 3 or 4 orders of magnitude to scale before it can even begin to compete with the LHC.
      • Re: (Score:3, Informative)

        by deglr6328 ( 150198 )
        Yeah the LHC produces proton collisions but protons are not fundamental particles, they are composite particles (3 quarks each + gluons)! They make "dirty" collisions with all sorts of particles flying everywhere. Electron positron collisions are much much "cleaner", the energy per individual fundamental particle is what matters. The international linear collider (a planned e- e+ collider) is hoped to achieve center of mass collisions of just 1 TeV and this will be sufficient to explore in depth the physics
        • Re: (Score:2, Informative)

          by Gromius ( 677157 )
          And just to elaborate on what you've hinted at for others, the reason this will never make the LHC redundant is to do with that the LHC does not have a fixed centre of mass energy in collisions as as you said, they are composite particles so while the protons collide at centre of mass energy of 14TeV, the individual quarks and gluons collide with a variable centre of mass energy (depends how much of the momentum is carried by that quark/gluon) upto a maximum of 14TeV. Anything produced by this development w
    • If you can get 1GeV in 3cm and 10GeV in a few meters, the LHC is redundant before it got completed.

      Yes, exactly! Because... it was... I mean, uh... wait.

      Er. Nope. Sorry. Didn't understand a word of that.

      Would someone care to translate?
      • Re:Imagine (Score:5, Informative)

        by AKAImBatman ( 238306 ) * <akaimbatman@gmail . c om> on Wednesday October 04, 2006 @12:52AM (#16301369) Homepage Journal
        We're talking about electron volts [wikipedia.org]. You see, electricity is not the electrons themselves, but rather a wave of energy passing from one electron to the next as they collide with each other. (A bit simplified, but hey.)

        You know those desk decorations that have about 5 metal ball suspended from wires? If you lift one and let go, gravity imparts energy on one of those balls. When it hits the next ball, it transfers energy to the other ball, which in turn hits the next ball, transfers its energy, so on and so forth. When the last ball has nothing more to hit, it swings out from the kinetic energy imparted on it. This is pretty much how electricity works.

        An electron Volt is a method of measuring the kinetic energy for individual particles. It translates directly to the voltage/joules calculations we all know and love, except that it only involves one particle instead of a wire full of them. Most commonly, this term is used in particle physics where the energy of a single particle matters.

        What has been built here is a micro particle-accelerator capable of imparting massive velocities on individual electrons. This is useful for things like advanced medical scanners [wikipedia.org] which bombard a target with a small number of high energy particles in order to get 3D image of the object. With a small enough particle accelerator, we could begin building devices like the medical tricorders you see in Star Trek. That's never been possible before.
        • Re: (Score:3, Informative)

          by Dachannien ( 617929 )
          You see, electricity is not the electrons themselves, but rather a wave of energy passing from one electron to the next as they collide with each other.

          Well, this depends on what context you're talking about. In a metal conductor, you're absolutely right - an individual electron crosses a potential difference at a speed much much less (generally a fraction of a millimeter per second) than that of the effect of electricity (which is close to c). In a vacuum, when energy is imparted by a particle accelerato
      • Oh, and the eggheads above are talking about combining a bunch of micro-acclerators to create the same velocities you'd find in the huge atom smashers. Their thought is that enough of these mini-accelerators might be able to outperform the Large Hadron Collider [wikipedia.org] being built in France. Which would be rather embarrassing when you consider the billions that have been spent on the project.
    • Using a plasma "afterburner" at SLAC, we were able to increase the energy of part of our beam from 43 GeV to ~100 GeV in the space of 1.2 meters. The main problem with all of this (plasma-wakefield particle accelerators as well) is getting high enough "current" to be useful. It is not that difficult to accelerate an electron or 2 up to that point, but to make a useful current is HARD. The absurdly short pulse durations necessary to create any kind of wakefield in the first place mean that 1) this is definit
  • idiot editors (Score:5, Informative)

    by 1u3hr ( 530656 ) on Wednesday October 04, 2006 @12:40AM (#16301313)
    "We believe we can [get to 10 GB]...
    GB = gigabyte
    GeV = giga electron Volts

    Also, TFA links to an illustrated version [lbl.gov] of the story.

    • Really. I was gonna say I've got a backup drive on my desk that gets to 320GB in only 17 cm. And the best they can do is 10GB in a meter?!?!

  • This advancement could create portable Free Electron Laser (FEL) [wikipedia.org], coolest laser around. The most interesting thing of FEl is that it can have variable wavelength.
    It can be tuned to just above the highest energy absorption line (the "K edge") of the chemical element, and that element can be used for total reflection mirror at grazing angles. Thus Lead can be used to create optic for FEL X-ray laser tuned to Lead K-edge. Effective X-ray laser becoming possible without any nuclear blast. And even portable X-
  • And I thought just zapping unsuspecting friends with a 50kv taser was fun. This thing is going to be a blast!

    -b
  • "We believe we can [get to 10 GB] with an accelerator less than a meter long

    That's great, I guess, but my Seagate gets to 160 GB, and it is much less than a meter long. So: hard drives are better than accelerators when it comes to storing data? And I'd wager that HD's require a LOT less power to operate, though I admit to not having RTFA yet.

  • This seems like we're on the way to tricorders. Handheld PET scanners, SWEET.
  • by A Brand of Fire ( 640320 ) on Wednesday October 04, 2006 @01:12AM (#16301473) Homepage

    When using a portable particle accelerator, always remember this important safety tip:

    Egon: There's something very important I forgot to tell you.

    Venkman: What?

    Egon: Don't cross the streams.

    Venkman: Why?

    Egon: It would be bad.

    Venkman: I'm fuzzy on the whole good/bad thing; what do you mean, bad?

    Egon: Try to imagine all life as you know it stopping instantaneously and every molecule in your body exploding at the speed of light.

    Ray: Total protonic reversal.

    Venkman: Right. That's bad? Okay. All right. Important safety tip. Thanks, Egon.

  • Where are you going to find a 40 TW laser that is considered portable? They don't mention how big the laser was. I would be willing to guess that a 40 TW laser takes up a fair amount of real estate.
    • While it's not exactly portable, it's not that big really. Now excuse me, I have a negotiation with Coka Cola about burning their logo on the moon.
      • Re: (Score:3, Funny)

        by emlyncorrin ( 818871 )
        Now excuse me, I have a negotiation with Coka Cola about burning their logo on the moon.
        Make sure you spell check their name before starting...
  • by Ruberik ( 935611 ) on Wednesday October 04, 2006 @01:51AM (#16301651)
    For anyone who's interested, the actual velocity of the electrons is about 0.999999869 times the speed of light -- which is why talking about GeV is more instructive than talking about how fast the particle goes. The math follows, if you're interested.

    1GeV = energy = gamma * m * c^2 (gamma = 1/sqrt(1-v^2/c^2))
    1 GeV / c^2 / m = gamma
    1957 = gamma = 1/sqrt(1-v^2/c^2)
    v/c = 0.999999869 ... or you can type sqrt(1-1/(1GeV / electron mass / c^2)^2) into Google Calculator.

    Interesting fact: we usually hear about E = mc^2. That's the direct matter->energy conversion when the matter is at rest: if the matter is moving, we add on a factor of "gamma" -- which, at small velocities, is about 1 + 1/2 * v^2/c^2 (giving E = mc^2 + 1/2 mv^2, or rest mass + classical kinetic energy!)
  • by viking80 ( 697716 ) on Wednesday October 04, 2006 @03:03AM (#16302005) Journal
    This device uses a relative modest 9TW. The submitter suggests some portable applications.

    I'll get one of these, throw away the whole electron/laser surf part, and just use the portable 9TW generator in my Toyota Prius.

    That should get me from 0 to escape velocity in 1 microsecond.
    • by treeves ( 963993 )
      Terawatts are not a measure of energy, they're a measure of power. Energy = power times time.
      If the pulse lasts only one attosecond, then 9TW gives you only nine-millionths of a joule. Not much energy at all.
  • I don't see how this is immediately very useful for electron-beam cancer therapy. This system seems infinitely complex compared to the current methods for generating electron beams--the one I can come up with off the top of my head is thermionic emission from a tungsten wire plus acceleration through a potential in vacuum. This process generates the keV-MeV range electrons that are necessary for therapy (I think) or for producing X-rays.

    Now, I'm a medical physics _student,_ so if anyone has some better i
    • Re: (Score:3, Informative)

      IAAMP (I Am A Medical Physicist)

      It is not for electron beams that this would be a boon. It is rather for other particles (protons, heavy ions). The footprint of such facilities is pretty large. In the US there are currently a number of proton treatment centers. Protons allow you to generate more conformal treatments (e.g. treating tumor not healthy tissue) with very low levels of doses elsewhere in the body. The latter is important for patients expected to have long survival times (these are becoming more

      • I just scanned through Michigan's yellow book (Ionizing Radiation Rules) and the section on particle accelerators = > 1MeV, talks about site surveys for shielding, interlocks ect. to the point it make any idea of portable and particle acceleator an oxymoron irregardless of flux density.
  • by Flying pig ( 925874 ) on Wednesday October 04, 2006 @03:29AM (#16302111)
    That we do have a real crisis in physics education. (Here in the UK, having had to pay bonuses to attract maths teachers, the Government is now making similar efforts with physics - rather late.)

    Reading the responses, there is frequently a lack of understanding of just how big this stuff is, just what it takes to produce things like wakefield accelerators and the difference between instantaneous power in watts and available energy.

    Which reminds me of a true story. One company I worked for, the MD (aka CEO) decided we had to have a carbon dioxide laser to replace the ruby laser in one of our products. He talked to an academic researcher and asked how big the laser would need to be. The researcher said 10cm long and was promptly hired.

    Six months later he had a prototype. The laser was a ceramic tube with fittings on a stand, genuinely about 150mm long with the fittings. Behind it was a room full of high voltage equipment, giant capacitors, carbon dioxide cylinders, extractor fans and, in fact, a water cooling system connected to a pressure main.

    It took the MD a litle time to realise that this stuff was all part of making the laser go. He then asked when it would all be reduced in size to fit into a hand held box. The researcher's response? "You never told me you wanted the electrics to go in a box. You just said you wanted a four inch long laser."

    • by Tim C ( 15259 )
      That we do have a real crisis in physics education.

      Yes, we do, but the responses here don't actually confirm that. For all its general techiness, this site is still primarily read by computer geeks. I've been alternatly ranting and cringing at replies to physics-heavy stories here for *years*. In fact, for a while, I simply stopped reading the comments to such stories, it wasn't worth the increase in blood pressure.

      I think, for me, the absolute low point was a thread disucssing what would happen if a nuke w
      • No, I do think they confirm it. They demonstrate that people who, thirty years ago, would have a grasp of basic physics, now do not. Obviously a poll of physicists and engineers would not tell you that, nor would a poll of arts graduates. But if people who are interested in technology no longer understand quite basic physics and engineering concepts, that is a pointer.
  • Am I missing something here? Is he talking about making F-18 portably? Didn't the article say the unit would be room-sized...like say a cyclotron, already used to make F-18? Also, you don't make F-18 using positrons. F-18 gives off positrons.
    • A cyclo itself is the size of a small grain silo, but the support gear that drives the unit takes up the rest of the building, particularly the power supply, vaccuum pumps, and shielding. To punch electrons up that fast in that short of run would shrink the unit and support gear to the size of two semi trailers.

      If someone could find a improved method of pulling a high vaccuum with less power and more speed, then that would be a fantastic bonus to physics.
  • I'm not much of a physicist but a while back in the mid 90s someone came up with a way to get
    MeV electrons by hitting a very thin metal foil with a laser.

    "High-energy electron beam production by femtosecond laser interactions
    with exploding-foil plasmas"

    http://xray.ipcf.cnr.it/archivio/PRE_RC_01.pdf [ipcf.cnr.it]

    They were already back then ten years ago jawing about cheap radiation equipment for example for
    radiation therapy etc. Nothing came of it, I wonder why Siemens or Varian or all the rest of the equipment
    manufacture
    • What do you mean "nothing came of it"? Its all ponderomotive charged particle acceleration and plasma wave acceleration using lasers. THIS is what came of it!
  • The production of positron emitting radioisotopes in a cyclotron, eg. F-18, requires the acceleration of a beam of protons - very different from electrons.

    And even if you can produce the isotope in a pocket-sized apparatus, the scanner itself - the array of scintillators, lightguides, photomultipliers, electronics and computers that the patient lays inside, is not exactly portable by any stretch of the imagination.
    • Actually, the scanners themselves are relativly portable. Mobile PET and PET/CT is a thriving market all over the United States and has been for a number of years. Check out Alliance Imaging's website, (google it). GE and Siemens both make mobile PET/CT now. OK class: Can anyone tell me the only positron-emmiting isotope used in medical PET scans isn't created in a cyclotron? Bonus: What type of PET imaging is it used for?
      • 82-Sr cardio
      • by Ihlosi ( 895663 )
        Actually, the scanners themselves are relativly portable ...



        "Portable" usually means "can be carried by one person", and I'd still say that even "mobile" PET or CT scanners don't qualify here.

  • "So its a ray?"
    "Yes."
    "That causes instant death?"
    "Yes."
    "Then why don't you just CALL it a DEATH RAY?"
    ~Eureka
  • by Attila the Bun ( 952109 ) on Wednesday October 04, 2006 @05:02AM (#16302489)

    PET scans don't use accelerated positrons. A radioisotope is injected into the patient, which emits a positron when it decays. The positron immediately annihilates with an electron and emits two gamma rays. The gamma rays are detected and used to build the scan. To make the radioisotope you need a proton accelerator, but these are already very compact at 2-3m diameter, and anyway don't need to be near the patient.

    Fusion, of course, has nothing to do with accelerating electrons.

    I thought geeks knew this stuff, or do they only need to pretend these days?

    • Re: (Score:3, Informative)

      by cheesybagel ( 670288 )
      Fusion may be done with accelerating particles or light.

      Try googling for "beam fusion" "inertial confinement fusion" and stuff like that.

      Here:

    • Re: (Score:3, Interesting)

      by khallow ( 566160 )

      Fusion, of course, has nothing to do with accelerating electrons.

      But it sometimes has something to do with accelerating charged ions. For example, accelerating protons at a target of 7Li or 11B could induce some degree of aneutronic fusion (ie, little of the fusion outcome would be energy-stealing neutrons). I don't think it'd be anywhere near breakeven, but it's a start.
    • Re: (Score:2, Interesting)

      by Kontinuum ( 866086 )
      There are a few PET/SPECT isotopes that require you to have a nearby cyclotron: 11C (20 minute half-life) and 82Rb (76 second half-life) for example. The vast majority of clinical studies are done using 18F (109 minutes), so generally speaking, you are right, you don't need to have the cyclotron too nearby. But, for some applications, it is in fact necessary.

      That said, I agree, it's very hard to see an application of laser-wakefield acceleration of electrons to PET.
  • "We believe we can [get to 10 GB] with an accelerator less than a meter long -- although we'll probably need 30 meters' worth of laser path."

    Holy moley - how much energy does 10Gb of data have?! That'd just punch right through a firewall, and set fire to the editors sitting the other side!
  • More importantly, considering that Earth is tech level ~9, does that mean that PGMP's really are more like tech level 10, not 12?
  • Using Google: 5.4e20 G's [google.com]. Whoa.

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