I was wondering, how one creates antiprotons. I've read somewhere that the energy calculation would be somewhere in the neighborhood of 4.3^13cak/ gram. what would it's absolute power be? it came to something along 300 gt explosive ouch! lol imagine what a few metric tons of the stuff could do^^
Antimatter
- Thread starter MiranoPoncho
- Start date
silverpig
Lifer
- Jul 29, 2001
- 27,703
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It's created by particle accelerators. If you fire protons head on with protons at a very high speed, they produce a number of other particles, antiprotons being some of them. If you're wondering how you can make a lot of matter out of just a little bit of matter like that, remember E=mc^2 and realize that the kinetic energy the protons have before the collision goes to mass of new particles after the collision.
And for the rest, it's simple E=mc^2 again. A few metric tons times c^2 = buhbye earth.
And for the rest, it's simple E=mc^2 again. A few metric tons times c^2 = buhbye earth.
I believe that CERN has an anti-proton trap, and is hoarding them slowly. Should be able to find a lot using google.
And dont think that A&D is in any way realistic. There is nada danger of CERN blowing up anytime soon.
Silverpig has it right. When you collide protons together with high enough velocities, you can generate antiprotons through the interaction
p + p -> p + p + p + p_
where p represents a proton and p_ represents an antiproton. The kinetic energy required to produce the extra proton/antiproton pair is 6 m_p c^2, where m_p is the mass of the proton, so antimatter production is not an extremely efficient means of producing energy.
Contrary to popular belief, matter antimatter annhilation is not perfectly efficient either. Protons are composite particles, and collissions will almost never result in all of the individual components annhilating. Instead, a proton antiproton collision generally produces a bunch of pions like:
p + p_ -> pi+ + pi- + pi0
The neutral pion, pi0, can decay into a pair of photons, but conservation of charge prevents a similar decay for the charged pi+ and pi- particles. Instead, they decay usually into muon, antineutrino or antimuon, neutrino pairs. Billions of neutrinos travelled through your body as you read this sentence, so as you might expect, the portion of the mass-energy they carry off isn't accessible for power or explosive potential. Matter-antimatter using antihydrogen or antiprotons ends up less than 50% efficient, which is still impressive compared to fusion which is closer to 1% efficiency of converting matter to energy.
At higher energies, proton-antiproton collisions produce a wide variety of exotic particles; that's how the particle accelerators at CERN and Fermilab work.
DrPizza
Administrator Elite Member Goat Whisperer
I haven't read much of Dan Brown's stuff, but IIRC, there's a lot of fiction mixed with the a bit of non-fiction.
flashbacck
Golden Member
- Aug 3, 2001
- 1,921
- 0
- 76
It'll take more energy to make your antiprotons than what you get out of it. So there's really no point unless you need to make a high energy/volume energy source.
Doesn't antimatter weigh in at 62.5 trillion per gram?!?!?! Jeez, if I ever said to my friends at school that something costed 62.5 trillion per gram...... lol
Agreed, but if you're into techy stuff, science, history, and a good mystery, his books are top notch. Read 'em, you won't be disappointed.
Jeff7
Lifer
- Jan 4, 2001
- 41,596
- 20
- 81
Yeah; they produce it a few thousand atoms at a time.
The previous HT post on Antimatter.
From that:
300 atoms per second. 86,400 atoms a day. At that rate, in about 19,083,016,420,767,105.25 years, not counting the slowing of Earth's rotation, we'll have one gram of antihydrogen. Small problem.
So maybe we'd need just a few more generators; using current technology, they're still very inefficient, and expensive. Thus the $62.5 trillion pricetag per gram.
Gibsons
Lifer
- Aug 14, 2001
- 12,530
- 35
- 91
okay, I have a buncha questions but all about the same thing really...
Would antimatter have the same general properties as 'normal' matter in most cases? ie would anti-water have the same freezing and boiling points as regular water? Would emission/absorbance spectra be the same (is the coupling constant the same for a positrons and electrons?) To take another track, say we train our telescope on some extra-solar body... can we say for certain if it's matter or antimatter or do any sort of measurement to find out either way?
Would antimatter have the same general properties as 'normal' matter in most cases? ie would anti-water have the same freezing and boiling points as regular water? Would emission/absorbance spectra be the same (is the coupling constant the same for a positrons and electrons?) To take another track, say we train our telescope on some extra-solar body... can we say for certain if it's matter or antimatter or do any sort of measurement to find out either way?
Yes, the CPT symmetry theorem states that antimatter behaves the same way that regular matter does. Due to the difficulty of producing quantities of antimatter, our experimental tests are necessarily restricted to those that we can apply to a few thousand atoms at most, and so we haven't verified aggregate properties of antimatter like the phase transition from gas to liquid, for example.
If an antistar was in a region of matter (or if a star was in a region of antimatter), it would be quite obvious from the intense gamma ray emissions from the interaction of the antistar's solar wind with the surrounding matter environment. One signature would be the presence of 511 keV photons from electron-positron annhilation. Interestingly, we do see such a signature near the core of the Milky Way.
If an antistar is present in a galaxy of antimatter, we couldn't distinguish it from a regular star though, since the antiparticle of the photon is itself and thus there's no difference in the light of an antistar from a regular star.
Fermilab and CERN are the only places to my knowlege that have ever made the stuff. Not sure who started doing it first.
I have a question, shouldn't there be an equal ammount of antimatter as matter? I know that after the big bang, there was nearly the same ammount of both matter and antimatter, and that much of it has annihilated. But shouldn't annihilations transform an equal ammount of both matter and matter into energy? So why has antimatter almost gone extinct?
If you don't require complete antiatoms, we've made it in tiny quantities since the 30's. Fermilab has the been the highest energy accelerator for some years, but the LHC at CERN will take the top position in a few years.
Good question.
There is only a very small amount of matter. There are about a billion photons for every proton or neutron. The photons may have been produced by matter-antimatter annhilation in the first few moments of the universe. Your question is why are there any protons left over, without an equal amount of antiprotons.
The reason is that the symmetry between matter and antimatter isn't perfect. The strong nuclear, electromagnetic, and gravitation forces treat antimatter identically to matter (with the obvious difference that the charge is opposite), but the weak nuclear force treats them differently by about 2 parts in 1000 in certain particle decays, such as those of neutral K and B mesons.
I'll have to get a bit technical now, by introducing symmetries under two operations:
[*]P Parity transformations, i.e. mirror reflections of space.
[*]C Charge conjugation, i.e. reverse the electric charge of a particle.
We expected physics to be invariant under parity transformations, but it turns out that there is a fundamental difference between left and right in nature that we can observe in particle decays. It turns out that the symmetry is restored if we also turn particles into antiparticles by applying the C operation, giving us the CP symmetry.
In 1964, we discovered that the weak force violates CP symmetry. CP symmetry should prevent the K0 meson from decaying into a p+p- pair, but occasionally (about 2 times in 1000), the K0 does decay that way. The discoverers won the Nobel Prize.
More recently, several special accelerator extensions were built, called B factories, such as the BaBar project at SLAC, to examine CP violation in B0 mesons, where it was predicted to also occur from our experience with K0s. Recent results point towards CP violation in B0 mesons as well. If CP symmetry held, a B0 should decay equally into K+pi- and K-pi+ pairs, but experiments show us that B0 prefers to decay to K+pi-.
It's a very small asymmetry, but the ratio of matter to photons indicates that the difference in amounts of matter and antimatter was very small too.
cquark, can you explain (or had ANYBODY) been able to explain the slight assymetry in matter/antimatter except by using the anthropic principle???
In the Standard Model, CP violation results from experimentally determined parameters (the CKM matrix.) It offers no theoretical reason for the CKM matrix entries having the values they do.
Some unification theories and string theory variants have been created to predict those parameters since we discovered CP violation, but string theory and unification theories currently have no experimental support. Yes, they agree with the Standard Model, but we can't experimentally test any of their predictions beyond those which agree with the Standard Model.
The LHC will help us test some of these theories, but while it can verify them (if there's a light supersymmetric partner, for example), it's too limited to rule them out altogether.
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