# Kaon discovered by the unusual fork

1. Jun 26, 2012

### nonequilibrium

Kaon discovered by "the unusual fork"

So historically (reading about it in Griffiths) the (neutral) kaon was discovered by noting that there was some neutral particle decaying into a positive and neutral pion.

But how did they know at the time (1947) that it was not the neutron doing this? Of course now we know this is not possible due to, say, baryon number. But how did they know it wasn't the neutron at the time. The only thing I can think of is that the kaon lifetime is shorter than the neutron's. Is that it?

2. Jun 26, 2012

### Staff: Mentor

Re: Kaon discovered by "the unusual fork"

Neutrons are "stable" in accelerator experiments - while you might see a decay from time to time, usual flight times are measured in nanoseconds, while the lifetime of the neutrons is several minutes.
In addition, if you can measure the momentum of the charged and neutral pion, you can reconstruct the mass of the decayed particle.

Charge conservation? Do you mean positive+negative pion?

3. Jun 26, 2012

### nonequilibrium

Re: Kaon discovered by "the unusual fork"

Yes, sorry, I meant negative.

And thanks for the answer.

4. Jun 26, 2012