Beta Decay & Quarks - A-Level Physics Explained

[matt_crouch]

In my A-level Physics course we have been talking about nuclear decay. When an nucleus decays by beta emission the proton number increases. My teacher described a neutron as "an electron and a proton" so that the overall charge is 0. To me this sounds like a simplification. what's really going on. I know that Protons and neutrons are made of quarks has it got something to do with an up quark changing to a down or something like that?

cheers =]

 

[CompuChip]

Yes, that's more or less precisely what's happening :)
This image displays it nicely:

The W^- particle is some elementary particle that only exists for a short while (a so called virtual particle). You see that a anti-neutrino (the "vee", or actually: "nu", with a bar) is released, which is a very light and very hard to detect particle. You don't really notice it's there, except it can take some energy with it.
The up and down quark, W-boson, electron and anti-neutrino are all (as far as the Standard Model of particle physics is concerned) elementary particles.

 

[matt_crouch]

ahh awesome. explains a lot
thanks

 

[CompuChip]

You're welcome. Just another small comment on this part:

My teacher described a neutron as "an electron and a proton"

He makes it sound like a neutron is composed of an electron and a proton, which is not just an oversimplification, it is wrong. What he probably meant was that the neutron can change into an electron and a proton (which is right up to the anti-neutrino).

 

[matt_crouch]

ahh ok i see.. thanks

 

[nrqed]

In my A-level Physics course we have been talking about nuclear decay. When an nucleus decays by beta emission the proton number increases. My teacher described a neutron as "an electron and a proton" so that the overall charge is 0. To me this sounds like a simplification. what's really going on. I know that Protons and neutrons are made of quarks has it got something to do with an up quark changing to a down or something like that?

cheers =]

I want to reiterate what Compuchip said: if your prof really did describe a neutron as an electron and a proton, he/she said something completely, totally, unforgivingly wrong.