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CERN Antimatter Experiment Produces First Beam of Antihydrogen 136

An anonymous reader writes "Matter and antimatter annihilate immediately when they meet, so aside from creating antihydrogen, one of the key challenges for physicists is to keep antiatoms away from ordinary matter. To do so, experiments take advantage of antihydrogen's magnetic properties (which are similar to hydrogen's) and use very strong non-uniform magnetic fields to trap antiatoms long enough to study them. However, the strong magnetic field gradients degrade the spectroscopic properties of the (anti)atoms. To allow for clean high-resolution spectroscopy, the ASACUSA collaboration developed an innovative set-up to transfer antihydrogen atoms to a region where they can be studied in flight, far from the strong magnetic field (scientific paper)."
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CERN Antimatter Experiment Produces First Beam of Antihydrogen

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  • by Anonymous Coward on Tuesday January 21, 2014 @04:33PM (#46029073)
    Sulphur Hexafluoride [] already does this.
  • by Mashdar ( 876825 ) on Tuesday January 21, 2014 @06:14PM (#46029985)
    Do you mean does away with dark energy? Because dark matter is supposed to have positive mass, so I don't see how adding negative mass would remove the need for it?
  • Re:First! (Score:5, Informative)

    by OneAhead ( 1495535 ) on Tuesday January 21, 2014 @08:53PM (#46031433)

    Here's a serious answer, just in case you're not going along with the joking tone of the 2 posts I replied to...

    I thought we were (implicitly) talking about the presence of air making terrestrial use of the weapon impossible. Particles coming loose tend to fly around at high speeds is somewhat random directions. Some of them will remain in the way of the antimatter projectile/beam, some of them will go out of the way but hit a molecule and return where they came from, some of them will create some backscatter effect (like a billiard ball being launched at high speed on a pool table full of other balls), causing molecules of air to get into the way. Even if one could fire a hypothetical ray that clearly annihilates all matter ahead of an antimatter projectile/beam, air would quickly rush into the vacuum being created (of course, having such a ray at one's disposal would mostly remove the point of using an antimatter projectile/beam). Whatever happens, there won't be the necessary hard vacuum for the antimatter projectile/beam to proceed. Even air at very low density would exert an incredibly strong braking/beam dispersal force because of the energy released when it collides with antimatter.

    Also, in the present discussion, gravity is far too weak a force to be relevant at all. If you have to wait for gravity to remove stuff out of the way, air will have been given time to take that stuff's place a hundred times over. That's why there's no hard vacuum behind objects in (subsonic) free fall. Now in space, there is no air, but little gravity either...

  • Re:ELIAAHM (Score:5, Informative)

    by joe_frisch ( 1366229 ) on Tuesday January 21, 2014 @08:58PM (#46031465)

    They turn into "energy", but it may not be very straightforward. Electrons and anti-electrons (positrons) usually annihilate to a pair of gamma rays - about as close to "pure" energy as you can get.

    Anti protons and protons annihilate in a more ugly fashion since each is a bag of quarks. You can get pions that decay into neutrinos and muons which then decay into positrons and neutrinos. The muon decay is fairly slow - ~2 microseconds, enough for them to travel almost a kilometer.

    In the end you get gamma rays, neutrinos (of various types), electrons and positrons. The combined energy (both their mass energy and their kinetic energy) of all the particles adds up to the original mass energy of the matter and antimatter, and any other energy put into the process.

    Because protons and anti-protons are complex, it is very difficult to make anti-protons - only something like 1/100,000 collisions generates one, the rest just make pions and other junk. Then once you have the anti-protons its difficult to slow them down enough and cool them to where they will combine with the positrons. Is a very impressive and complicated experiment.

    BTW- it is not a path to any reasonable energy storage, the efficiency of making anti-protons is much too low. I don't know of any even design concepts that would have usable efficiency.

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