Particle creation.

[Xyph]

OK, there are a few things I don't really understand about this, so I'd appreciate it if someone could explain the following in layman's terms, assuming it can be done in such a way...

 

 

1) How exactly is antimatter produced? It's done in particle accelerators, I know, but since, presumably, all there is to work with is matter, I find it hard to see how antimatter can be got out of it.

 

2) Having established that antimatter can be produced in some way, and given that, for example, a positron and an electron will annihilate each other in a burst of gamma rays, apparently the energy resulting from such annihilation can be used to create these particles again - but can it be done this neatly in actuality? How exactly are the energies focused into forming particles? Will concentrated photons always coalesce into particles with mass at some point?

 

3) Given that particles can be created, somehow, is there a way to control the output at all, or is it necessarily left to chance? Could theoretical particles such as WIMPs, gravitons or exotic matter be produced using a similar method?

[swansont]

OK' date=' there are a few things I don't really understand about this, so I'd appreciate it if someone could explain the following in layman's terms, assuming it can be done in such a way...

 

 

1) How exactly is antimatter produced? It's done in particle accelerators, I know, but since, presumably, all there is to work with is matter, I find it hard to see how antimatter can be got out of it.

 

2) Having established that antimatter can be produced in some way, and given that, for example, a positron and an electron will annihilate each other in a burst of gamma rays, apparently the energy resulting from such annihilation can be used to create these particles again - but can it be done this neatly in actuality? How exactly are the energies focused into forming particles? Will concentrated photons always coalesce into particles with mass at some point?

 

3) Given that particles can be created, somehow, is there a way to control the output at all, or is it necessarily left to chance? Could theoretical particles such as WIMPs, gravitons or exotic matter be produced using a similar method?[/quote']

 

Aprticle/antiparticle pairs are created from energy, e.g. from a photon, or from the collision between particles of matter that have sufficient kinetic energy. So the matter is just a means to an end, it's the energy that's important.

 

Since annihilation requires the production of at least 2 photons in order to conserve momentum, these will have insufficient energy to recreate the same particle/antiparticle pair.

 

Exotic matter is a goal of some research, but not every particle (or proposed particle) could be formed in any given accelerator.

[arkain101]

I am 99% sure anti matter is a name for matter which has particles that are spinning in the opposite direction of our matter which rotates in a left hand turn. Any matter that has the opposite rotation has different physics behind it. Light is changed from it somehow so we cant detect it through site, it would appear invisible..

they say likes repel, and maybe that keeps the particles in our world from coming in direct contact.. but I guess when the two opposite types of matter they interact with 99% efficiency, and I heard that a thimble of anti matter would go off like a nuclear bomb. so i hope the people playing with it be really careful..

[CPL.Luke]

the people who work with antimatter only are capable of creating and using a few dozen atoms.

[Severian]

1) How exactly is antimatter produced? It's done in particle accelerators' date=' I know, but since, presumably, all there is to work with is matter, I find it hard to see how antimatter can be got out of it.

[/quote']

 

Not all particles come in particle/anti-particle pairs. Some particles are their own anti-particle. Photons are like this (as are many others). So a photon can split into an electron-positron pair. This is the reason why photons are usually not classified as 'matter' - particles which have distinct anti-particles are called 'matter', while their antiparticles are called 'anti-matter'. This inlcudes all the quarks and leptons (electrons etc).

 

You can make a beam of positrons by turning photons into electron-positron pairs and then separating the electrons from the positrons with a magnetic field.

 

The LHC will collide protons with protons, so it doesn't need antimatter in the beam. However, the gluons in the proton can turn into particle-antiparticle pairs in much the same way as the photon.

 

2) Having established that antimatter can be produced in some way, and given that, for example, a positron and an electron will annihilate each other in a burst of gamma rays, apparently the energy resulting from such annihilation can be used to create these particles again - but can it be done this neatly in actuality? How exactly are the energies focused into forming particles? Will concentrated photons always coalesce into particles with mass at some point?

 

If you have a positron and electron annihilate to form a photon in the collider, the photon will usually decay pretty quickly. This is because the photon (usually) borrows energy using Heisenberg's uncertainty principle and must give it back rather quickly. However, what it decays into is not fixed. As long as it has enough energy to create the new particles (and usually in a collider it has lots of energy), it can decay into any charged particle-antiparticle pair. For example, it can decay into a quark-antiquark pair.

 

However, the collider doesn't just collide one elctron with one positron. It collides lots of them together (in bunches). Often none of them will hit (there is a lot of space in between ) but sometimes two will collide.

 

3) Given that particles can be created, somehow, is there a way to control the output at all, or is it necessarily left to chance? Could theoretical particles such as WIMPs, gravitons or exotic matter be produced using a similar method?

 

No - it is left pretty much to chance. There is no way to direct what will come out, so you can in principle create 'exotic' matter if you have enough energy.

 

However, you may be able to influence which particles are produced a little by using polarized beams or by tuning the energy. For example, the LEP collider ran for a long time with the centre-of-mass energy tuned to the mass of the Z-particle - this guaranteed lots of Z's to study.

 

At the LHC, one of the aims will be to produce supersymmetric particles, the lightest of which is a good dark matter candidate.

 

 

I am 99% sure anti matter is a name for matter which has particles that are spinning in the opposite direction of our matter which rotates in a left hand turn. Any matter that has the opposite rotation has different physics behind it.

 

Anti-matter will have the opposite spin of its particle partner, but they can both be left or right handed, so this isn't a definition or distinction of antimatter. I can produce a left-handed particle with a right-handed antiparticle, but I can also produce a right-handed particle with a left-handed antiparticle. You may be confused by the weak interaction, which only couples to left-handed objects.

[elas]

[quote=

1) How exactly is antimatter produced? .

 

We observe what happens and from observations produce a predictive theory, we do not as yet, know 'how or why' changes occur. You will find a statement to this effect in the introduction to most QT primers.