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Anti-Matter Created By Laser At Livermore

Posted by kdawson on from the billions-and-billiions dept.

zootropole alerts us to a press release issued today by Lawrence Livermore National Laboratory, announcing the production of 'billions of particles of anti-matter.' "Take a gold sample the size of the head of a push pin, shoot a laser through it, and suddenly more than 100 billion particles of anti-matter appear. The anti-matter, also known as positrons, shoots out of the target in a cone-shaped plasma 'jet.' This new ability to create a large number of positrons in a small laboratory opens the door to several fresh avenues of anti-matter research, including an understanding of the physics underlying various astrophysical phenomena such as black holes and gamma ray bursts." The press release doesn't characterize the laser used in this experiment, but it may have been this one.

9 of 465 comments (clear)

  1. Holy Mackerel! by AKAImBatman · · Score: 5, Interesting

    Does anyone know how much energy this takes? They mentioned the previous petawatt laser experiment that was decommissioned, but I didn't see where it mentioend the power required for this experiment. If the laser guess by kdawson is correct, we could be looking at a mere 400 joules per 1E11 positrons. Which (if I'm not mistaken) would be an unheard of efficiency for creating antimatter! (Can someone verify? My brain is fried at the moment.)

    What I find interesting is that this level of production is competitive with Fermilab. Even if they ran this twice an hour, they'd handily meet or outstrip Fermilab production.

    Even more interesting is the possibility for mass manufacture of antimatter. By using mass-produced gold targets, you could rotate the materials in and out of the machine every few seconds, creating previously unseen amounts of antimatter. Such a process could easily provide materials for an antimatter catalyzed fission drive. Possibly even enough to power new forms of interplanetary propulsion.

    Am I the only one who's getting really excited about this? /dreamer

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    1. Re:Holy Mackerel! by techno-vampire · · Score: 4, Interesting

      It's even worse than that. During a panel at LACon II, back in '84, Dr. Robert Forward said that according to the best calculations, if you dropped a lump of anti-matter on the floor, it wouldn't vanish in a flash of gamma rays, it would sizzle like a drop of water on a hot griddle. You see, the anti-matter can only interact with its environment and annihilate on its surface, and there's this little thing called the "cube-square law" that says that very little of it is going to be on the surface.

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    2. Re:Holy Mackerel! by Klaus_1250 · · Score: 3, Interesting

      (60e6 * 1e3 kcal) / (c^2) = 2.7931967 grams. That is about a factor 1000 less.

      The largest H-bomb ever build/detonated, the russian Tsar Bomb, was about 50MT, but capable of 100MT. I never heard of anything larger, but is/was there?

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    3. Re:Holy Mackerel! by Rayban · · Score: 3, Interesting

      What would happen if you aerosolized said cube with a small explosive?

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    4. Re:Holy Mackerel! by Quantum+Jim · · Score: 3, Interesting

      I don't think this compares with Fermilab. The fine article is talking about creating positrons, not anti-protons. This isn't the first time I've heard about creating positrons from a laser shown upon a gold foil target. Here are two (from 2004 and 2001 respectively) that I just found on Google Scholar describing a result and a theory behind the positron production:

      http://llacolen.ciencias.uchile.cl/~vmunoz/download/papers/wclpp05.pdf
      http://www-project.slac.stanford.edu/lc/local/PolarizedPositrons/doc/ClassicalPapers/B_Shen-J_Meyer-ter-Vehn-PRE65_16405.pdf

      It also isn't very efficient. They make 10^11 positrons per 400 J of energy input. If those positrons react with 10^11 electrons, they produce gamma rays with the energy 2 * (electron mass * (10^11)) * (c^2) = 0.0163742083 joules. Maybe it is more efficient than Fermilab, but that's still not very much. Since these are light positrons - not heavy anti-protons - I don't think these results would be very useful for fusion. Maybe as a source of gamma rays or as a research tool.

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    5. Re:Holy Mackerel! by JohnFluxx · · Score: 5, Interesting

      I did the calculations for an earlier post:

      If you accelerate at 9.8m/s^2 for half the journey and -9.8m/s^2 for the second half of the journey (so that it's just like earth's gravity) then you would arrive at the planet after:

      1.94 arccosh(n/1.94 + 1) years

      For n=10.5 light years, this gives 4.9 years.

      For other values of distance:
      4.3 ly nearest star 3.6 years
      27 ly Vega 6.6 years
      30,000 ly Center of our galaxy 20 years
      2,000,000 ly Andromeda galaxy 28 years

      (For distances bigger than about a thousand million light years, the formulas given here is inadequate because the universe is expanding. General Relativity would have to be used to work out those cases.)

      So for someone in the rocket, they could arrive at the planet in 4.9 years.

      If you had an 100% efficient engine (using anti-matter/matter), the fuel required would be:

      d Stopping at: M
      4.3 ly Nearest star 38 kg
      27 ly Vega 886 kg
      30,000 ly Center of our galaxy 955,000 tonnes
      2,000,000 ly Andromeda galaxy 4.2 thousand million tonnes

      I find it fascinating that within a human lifetime (for the people in the rocket) we could travel to another galaxy.

      (I'm a theoretical particle physicist)

  2. Re:Lasers by superdave80 · · Score: 4, Interesting

    It's even more amazing when you consider that when lasers were first developed, no one thought they would have much practical use. They were "A solution looking for a problem."
    http://www.press.uchicago.edu/Misc/Chicago/284158_townes.html

    Now, try to imagine modern technology without lasers...

  3. Re:Quick question for anyone with the knowledge by CroDragn · · Score: 5, Interesting

    You can't generate a net positive energy source with antimatter. Best you can hope for is to use the antimatter as a form of energy storage (think battery, fuel, etc). Of course, storage problems make it impractical for nearly every use, so don't expect anti-matter cars... ever. Space travel, however, would greatly benefit from a decent means of generating antimatter, since fuel mass trumps most other concerns in that field and anti-matter provides the most thrust/mass of any theoretical substance.

  4. Re:Quick question for anyone with the knowledge by Elladan · · Score: 3, Interesting

    I heard on TV that an omnipotent sky monkey plans to torture us all in a volcano forever because some woman made out of a guy's rib ate a snack with a talking snake.

    And that was supposed to be an education show!