Determining particle spin in collision experiments

[JustinLevy]

How can high energy physicists determine the spin of a particle that decays before even reaching the silicon detectors?

For example if a new particle turned out to have spin 3/2, how would it be distinguished from a spin 1, spin 1/2, or spin 0 particle?

 

[Vanadium 50]

Usually by the angular distribution of their decay products.

 

[JustinLevy]

Angular distribution with respect to what?

And since the spin can't be known for each particle, wouldn't this require the production of the particle to be spin polarized?

 

[Vanadium 50]

Pick your favorite frame. The literature is full of them: Gottfried-Jackson (yes, that Jackson), Collins-Soper, Helicity.

It does not require polarization. It requires that the density matrix not be equally populated, which is similar but less restrictive.

 

[Meir Achuz]

There are number of ways of measuring spin, besides polarization.
The spin of the neutrino was 'measured' to be 1/2 because the other three particles in
neutron decay had spin 1/2.
Some spins are measure by recognizing the factor 1/(2s+1) in the cross section.
... and so on.