Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Is neutron-neutron fusion easier to facilitate than proton-proton

  1. Dec 29, 2007 #1
    Hi:

    Neutron-neutron fusion is an example of nuclear fusion because neutrons
    are nucleons. Is it possible to solve the energy crisis using
    neutron-neutron fusion? Can this fusion be used to generated sufficient
    amounts of power? One advantage to neutron-neutron fusion over H-H
    fusion is that, neutrons don't have charge. Unlike protons which are
    positively charged and repel each other, neutrons are neutral so it
    shouldn't require nearly as much energy to fuse neutrons as to fuse protons.

    I've searched on other internet about neutron-neutron fusion, however, I
    haven't received anything about its use for energy. All that show up are
    neutron beams. Why?

    Happy Holidays,

    Radium
     
  2. jcsd
  3. Dec 29, 2007 #2

    mathman

    User Avatar
    Science Advisor
    Gold Member

    I have never heard of n-n fusion. However, even if such a reaction was possible, there would be serious difficulties. The two major fusion for energy apporaches are plasma and laser compression.
    For the plasma, the key is getting the particles (H2+ or H3+) going fast enough to collide and fuse. A toroidal array of magnets is needed to accelerate these particles - there is no comparable method of accelerating neutrons, because they are neutral.
    For the laser, the target consisting of H2 and H3 inside a spherical container. The target is then zapped by an array of laser beams which simultaeously heat and compress the target and induce fusion. There is no way to collect neutrons and put them in a container.
     
  4. Dec 30, 2007 #3
    The theoretical possibility of n-n fusion is considered in this paper:

    http://arxiv.org/PS_cache/nucl-th/pdf/0507/0507048v2.pdf

    but the author states that it would be enormously difficult to observe. BTW, this paper was published in Physics Letters B,
    Volume 633, Issues 2-3, 9 February 2006, Pages 253-259.
     
  5. Dec 31, 2007 #4
    Another note on this subject - let's put fusion aside for the moment, and just think about n-n scattering. The scattering length, a fundamental parameter in defining the scattering cross section, has not been yet measured directly for free neutron scattering. Indirect measurement gives conflicting values of -18.6 fm and -16.5 fm. Whether charge symmetry is broken or conserved depends on which of these values is correct, for example. Measurement for free neutrons is possible, in principle, but difficult to do. Free neutrons are unstable, with a half-life of about 15 minutes, so one is not able to prepare a fixed neutron target. You have to work with beams. Because neutrons are neutral in charge (although, they have a magnetic moment), it is not easy to make a very dense beam of neutrons. Hence, such a measurement is difficult. It is not hard to extrapolate from this to it being even more difficult to get measurements on n-n fusion, let alone commercial energy production. However, this was a reasonable question to ask, and I appreciate Radium for having raised it. Also, here is an interesting paper on the subject:
    http://nvl.nist.gov/pub/nistpubs/jres/110/3/j110-3mit.pdf
     
  6. Dec 31, 2007 #5
    Green Xenon [Radium] <glucegen1@excite.com> wrote:
    > Neutron-neutron fusion is an example of nuclear fusion because neutrons
    > are nucleons. Is it possible to solve the energy crisis using
    > neutron-neutron fusion? Can this fusion be used to generated sufficient
    > amounts of power?


    Alas, the dineutron isn't stable, so trying to form it via fusion,
    via the reaction
    n + n --> 2n
    would not be an energy *source* (the reaction *absorbs* energy). :(

    --
    -- Jonathan Thornburg (remove -animal to reply) <J.Thornburg@soton.ac-zebra.uk>
    School of Mathematics, U of Southampton, England
    "Washing one's hands of the conflict between the powerful and the
    powerless means to side with the powerful, not to be neutral."
    -- quote by Freire / poster by Oxfam
     
  7. Dec 31, 2007 #6

    The reaction studied by Ando and Kubodera (linked in one of my earlier posts above) was not

    n + n --> 2n,

    but rather,

    n + n --> d + e+ nu_e.

    So, your reasoning for dismissing the possibility of n-n fusion (instability of the di-neutron) does not seem to me to be valid.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Is neutron-neutron fusion easier to facilitate than proton-proton
Loading...