# What triggers beta decay?

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1. Oct 31, 2015

### Joespires

I am familiar with the proton:neutron ratio and stability but what about this instability actually causes a quark to emit a boson and change flavour?

And what does this have to do with the weak nuclear force?

Thanks

2. Oct 31, 2015

### Staff: Mentor

It is a possible reaction, so it happens at some point. There is no specific "trigger" necessary.
The weak nuclear interaction allows this decay, without it beta decay would be impossible as all quark flavor numbers would be conserved.

3. Oct 31, 2015

### vanhees71

Also the usual $\beta$ decay doesn't emit a boson, but a neutron decays via the weak interaction into a proton, an electron and anti-electron neutrino (on the quark level a d-quark decays to a u-quark, an electron and an anti-electron neutrino).

4. Oct 31, 2015

### Joespires

Ok, thank you @mfb. In what way does it allow it? By the creation of a virtual boson to transfer the mass and charge?
@vanhees71 but it is carried by a virtual boson?

5. Oct 31, 2015

### vanhees71

That's true, it's a W-boson.

6. Nov 2, 2015

### bwana

Beta decay as well as all the other kinds of spontaneous particle emission the unstable nuclei emit are often spoken about as 'random' events. Is there a particular nuclear decay that is also accompanied/preceded by photon emission? Is it possible to predict a beta decay from a preceding pattern of photon/particle emissions? Like trying to predict an earthquake, are there 'markers' for imminent beta or alpha decay? Such an event might allow understanding of the intranuclear changes leading to beta decay.

I too have always been curious about nuclear decay that preserves the tendency for neutron-proton equivalence along with a slight bias of excess neutrons over protons but that's off topic.

7. Nov 2, 2015

### Staff: Mentor

You can have a photon emission, leading to a different excitation of the nucleus that decays via beta decay later - but that point in time is random again. You cannot predict it.
No.
They are understood very well.

8. Nov 4, 2015

### ChrisVer

If I recall well, a LOT of nuclei after releasing beta or alpha particles (so change to different nuclei) do so by going to an excited state of that nuclei and so you get the additional radiation of gamma (by the transition from the new nucleus's excited to its ground state).

You cannot predict a single beta decay...you can however get a probability for it to happen in your sample of many nuclei. That's why I'd call it random. An earthquake is not a random event (at least not if you try to predict it by probably -no expert on that- checking the vibrations of the ground->the motion of the tectonic plates -> the source of the earthquake).

9. Nov 4, 2015

### gleem

Remember, What is not forbidden is allowed.