What would happen if

[SpecialKM]

What would happen if a proton and an electron collide, has this been done before? I tried looking for an answer and all I've seen is what might happen.

 

[Drakkith]

If there is sufficient energy they could form into a Neutron briefly, and at higher energies you would collide them together and get a shower of particles created from the collision. There is no exact answer, as all the products of this are effectively random to a degree.

 

[BruceW]

Yeah, generally there will be a lot of different things that could happen, each with its own probability (as is the way quantum mechanics usually works).
In the specific case of a free electron and free proton, I don't know.

 

[SpecialKM]

How would it form into a neutron, even briefly? I thought when a neutron decays it forms a proton, electron and an anti-neutrino, wouldn't an anti-neutrino be needed in the collision to re-form a neutron?

Also, addressing the shower of particles, where do those particles come from? The proton or electron, or both?

 

[0xDEADBEEF]

When a neutron decays you get an anti-neutrino, when a proton captures an electron, it simply emits a neutrino. http://en.wikipedia.org/wiki/Electron_capture The decaying particles can just send out anti particles if they want to capture another particle but cannot do it.

If you pump enough energy into it particles get born out of the vacuum. There are some very "fat" short lived ones that otherwise never exist. This is what the LHC is looking for, by just colliding protons

 

[SpecialKM]

For electron capture to occur, there needs to be a nucleus, what if it's a single proton and a single electron?

Would it form hydrogen? Or a neutron? Or form into a neutron and shortly after decays back into a proton and electron + anti-neutrino.

 

[Drakkith]

For electron capture to occur, there needs to be a nucleus, what if it's a single proton and a single electron?

Would it form hydrogen? Or a neutron? Or form into a neutron and shortly after decays back into a proton and electron + anti-neutrino.

The nucleus of Hydrogen IS a proton. I'm guessing that electron capture can happen with it. I don't actually know if shooting an electron and proton at each other WOULD form a neutron, it simply inferred from other knowledge that is could, I could be wrong.

Attempting to smash a proton and electron together at high speeds wouldn't form Hydrogen for multiple reasons, one of which is that the velocities are too great to allow the proton to capture the electron in an orbital.

 

[SpecialKM]

Okay, so we have it narrowed down to 3 probable(?) possibilities:

1) A shower of sub-atomic particles
2) A neutron is formed, and remains a neutron
3) A neutron is formed, and shortly it decays into proton, electron and anti-neutrino

Also, a new discovery was made that an electron's charge is even throughout, so it stays a mono-pole and has no dipole moment. Is this the same with a proton?

 

[Drakkith]

No, a proton is composed of three quarks, two Up quarks and one Down quark.

Also, number 2 and 3 should be combined into: A neutron is formed with the standard half life of a free neutron.

 

[Fun Value]

The nucleus of Hydrogen IS a proton. I'm guessing that electron capture can happen with it. I don't actually know if shooting an electron and proton at each other WOULD form a neutron, it simply inferred from other knowledge that is could, I could be wrong.

Attempting to smash a proton and electron together at high speeds wouldn't form Hydrogen for multiple reasons, one of which is that the velocities are too great to allow the proton to capture the electron in an orbital.

Doesn't electron capture mean the electron is taken from an orbital and absorbed into the proton? It sounds like you are saying the hydrogen is formed by making an atom of a proton with an orbiting electron.

 

[Drakkith]

Yes, I meant it as the electron bonding with the proton to form Hydrogen. Not actual electron capture.

 

[SpecialKM]

So.. is it possible that a collision between an electron and proton happens and the result is that the proton completely breaks apart, because it is able to, since it's made up of quarks and the electron is uniform given enough energy of course.

But that in it self is hard to imagine, since the proton is 1800x more massive than the electron, and having more momentum.

Could the electron walk away from the collision unscathed?

 

[Drakkith]

First, the proton wouldn't "break apart" in the normal sense. The 3 quarks that compose it wouldn't be broken from each other and fly off in different directions. This is because the strong force (or color force) between the quarks DOESN'T decrease in strength with distance. Instead, when the quarks are forced further and further apart, at a certain point it becomes more favorable to simply create new quarks with the energy that you add. We have observed through experiments in accelerators that quarks are NEVER found alone, the always come in pairs or groups. The result is that when you hit the proton hard enough, you have a shower of new particles created from the protons "destruction".

I don't know for sure, but I'm assuming that at the energy levels needed to cause this to happen, the electron would also be "destroyed" and new particles created as well. (I don't call it annihilation because that is specific to matter-antimatter annihilations)

 

[SpecialKM]

Ah, alright. So given high enough energies both the electron and proton will just create a shower of other particles. Has this collision been done before? I would like to read more about it.

 

[Drakkith]

Yes, the collisions have been done thousands if not millions of times over the last 60 or so years. Look up particle accelerators on wikipedia and it should have a list of all the accelerators that have been operational. Other than that I don't really have a specific link to anything. Just dig around a bit and you should find plenty of info.

 

[SpecialKM]

Yeah, I've done that and it gives all different kinds of collisions, but none regarding a proton-electron collisions.

 

[Drakkith]

Actually, I have to apologize, as I don't actually now about the electron - proton collisions. I thought I had seen something where they had done it, but after a quick look I didn't see anything. I'll have to look a little deeper when I get a chance. I'm still pretty sure that the results of a collision between them would be just like we described, but I'd need to find something to back myself up. (Colliding any type of particles together results in about the same results as far as I know, as long as the energy levels are equal.)

 

[Andy Resnick]

What would happen if a proton and an electron collide, has this been done before? I tried looking for an answer and all I've seen is what might happen.

You must not have looked very hard:

http://www.particlephysics.ac.uk/news/picture-of-the-week/picture-archive/electron-proton-collisions-at-hera.html [Broken]

 

[Drakkith]

Ah, there we go. Thanks for the link Andy. I knew I had seen something somewhere about this.

 

[SpecialKM]

Oh, thanks Andy! I actually clicked that link on google, but didn't read any of it because I thought it was just news and not an explanation on the collision. Ahah, woops :P