Anti-Matter Created By Laser At Livermore 465
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.
Holy Mackerel! (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 [fnal.gov]. 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 [wikipedia.org]. Possibly even enough to power new forms of interplanetary propulsion.
Am I the only one who's getting really excited about this? /dreamer
All or Nothing (Score:2, Interesting)
Wow PET scans anyone? (Score:3, Interesting)
This may open the possibility of cheaper PET scans. Currently, the limitation of PET scans is the answer to this question: "How far away is the nearest Cyclotron?" The half life of the radioactive material used in Positron Emission Tomography, typically Flourine-18, is ~110 minutes. With a laser that can generate positrons, you could have a mobile PET scan unit that would only need to rely on being able to connect to the grid.
BTM
Re:Lasers (Score:5, 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 [uchicago.edu]
Now, try to imagine modern technology without lasers...
Re:All or Nothing (Score:2, Interesting)
Something goes wrong storing a nuke: Area sealed off, that particular spot possibly radioactive
Something goes wrong storing an antimatter bomb: Area vaporized, that particular spot the center of a city-sized crater
What about gold-nanoparticles instead (Score:1, Interesting)
Re:Holy Mackerel! (Score:5, Interesting)
Re:Holy Mackerel! (Score:4, 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?
Re:Holy Mackerel! (Score:4, Interesting)
What would happen if you aerosolized said cube with a small explosive?
Re:Holy Mackerel! (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 [uchile.cl]
http://www-project.slac.stanford.edu/lc/local/PolarizedPositrons/doc/ClassicalPapers/B_Shen-J_Meyer-ter-Vehn-PRE65_16405.pdf [stanford.edu]
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.
Re:Quick question for anyone with the knowledge (Score:5, Interesting)
Re:Holy Mackerel! (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)
Re:Quick question for anyone with the knowledge (Score:3, Interesting)
I spent a while thinking if you could exploit the W boson which produces anti-matter - matter pairs of different flavour but I couldnt think of a way. Regardless any way which somebody could come up with would give such a small theoretical energy gain that you would almost certainly lose it through efficiency loses.
Re:Holy Mackerel! (Score:2, Interesting)
Also, when you write it this way, it makes the impact of "20 megaton" nuclear bombs a lot more powerful. Pin not indented.
Re:Quick question for anyone with the knowledge (Score:1, Interesting)
Of course, lasers might not be the most energy efficient way of creating antimatter but that doesn't change the fact that if you want to turn m matter into antimatter you will need at least 2*mc^2 energy (at least that's my intuitive guess).
According to my intuition, your intuition is in error. Even if we're creating the antimatter from whole cloth we would be spending:
mc^2 + processing inefficiencies
But during the annihilation, a matter particle is also annihilated producing:
2 mc^2 - processing inefficiencies
Thus, the total released energy is something along the lines of:
mc^2 - 2 * processing inefficiencies
Whether or not we can develop a process where the second part of the equation doesn't dominate (that doesn't go on to level the city) is the real question.
Re:Quick question for anyone with the knowledge (Score:2, Interesting)
Re:Quick question for anyone with the knowledge (Score:4, 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!